How Does The Kinetic Energy (Movement) Of Particles Change Throughout Lab?

extra advanced notes on gas laws, ideal and non-ideal gases

GASES, LIQUIDS and SOLIDS

A pplication of the particle model to the three states of affair

Using the particle models to describe and explain the properties of gases, liquids and solids and state changes betwixt them

See likewise P-Five-T force per unit area-volume-temperature gas police force calculations

Doc Chocolate-brown'south Chemistry KS4 science GCSE/IGCSE Revision Notes

Sub�index for Parts 1 to 3 (this page) :

0 Introduction What are the three states of matter?

ane.1 Three states of affair - what can we expect from particle models and are in that location limitations?

ane.1a Backdrop of gases - particle model and properties explained and diffusion experiments

i.1b Properties of liquids - particle model and properties explained and diffusion experiment

1.1c Properties of solids - particle model and properties explained

two. Land changes - a summary diagram

2a Evaporation and boiling - explained using particle model

2b Condensation - explained using particle model

2c Distillation - explained using particle model

2d Melting - explained using particle model

2e Freezing-solidifying - explained using particle model

2f Cooling and heating curves - state changes and relative energy changes

2g Sublimation - explained using particle model

2h Comparison of latent heat changes in concrete changes of state for different substances

3a-d. (a) Dissolving, (b) Solutions, (c) Miscible liquids & immiscible liquids, (d) Separating funnel

Appendix 1. Particle pictures of elements, compounds & mixtures

GCSE multiple choice QUIZ on states of affair � gases, liquids & solids

GCSE�AS (bones) chemistry KEYWORD index for Office 1 (this page): Boiling * Boiling point * Brownian move * Changes of state * Condensing * Cooling curve * Diffusion * Dissolving * Evaporation * Free energy changes & change of state * Freezing * Freezing point * Gas particle picture * Heating bend * Liquid particle flick * Melting * Melting bespeak * miscible/immiscible liquids * Particle pictures of elements, compounds & mixtures * Backdrop of gases * Properties of liquids * Backdrop of solids * solutions * sublimation * Solid particle picture

Sub�index for Role 2 (on divide more advanced pages): A Level 4. Introduction to the kinetic particle theory of an platonic gas * Kelvin temperature scale * 4a Kelvin temperature scale and Boyle's Law * 4b. Charles's�Gay Lussac's Law and the combined gas law equation * A Level but 4c. The ideal gas equation PV=nRT * 4d. Dalton's Law of partial pressures * 4e. Graham's Law of improvidence * 5a. The deviations of a gases from ideal behaviour and their causes * 5b. The Van der Waals equation of state * 5c Compressibility factors * 5d The Critical Point � The Critical Temperature and Disquisitional Force per unit area *

Doc Dark-brown's chemical science revision notes: basic school chemistry science GCSE chemistry, IGCSE chemistry, O level & ~US grades 8, 9 and 10 school science courses or equivalent for ~14-16 yr one-time science students for national examinations in chemistry

part 0 Introduction

You should know that the three states of matter are solid, liquid and gas. Melting and freezing accept place at the melting betoken, boiling and condensing take place at the boiling point. The 3 states of matter tin be represented by a simple model in which the particles are represented by small solid spheres. Particle theory can aid to explain melting, humid, freezing and condensing.

The amount of free energy needed to modify land from solid to liquid and from liquid to gas depends on the strength of the forces betwixt the particles of the substance and the nature of the particles involved depends on the type of bonding and the construction of the substance. The stronger the forces between the particles the higher the melting signal and boiling point of the substance. For details encounter structure and bonding notes.

The forcefulness of the forces betwixt particles depends on the material (structure and type of bonding), the temperature (affects the energy of the particles) and pressure level (how close the particles are compressed together e.g. in a gas).

The concrete state a material adopts depends on its structure, temperature and force per unit area.

State symbols used in equations: (chiliad) gas (fifty) liquid (aq) aqueous solution (south) solid

aqueous solution means something dissolved in h2o,

a good example of how to use the state symbols correctly is calcium carbonate dissolving in hydrochloric acid:

CaCO_three (s) + 2HCl(aq) ====> CaCl₂ (aq) + H_iiO(fifty) + CO_ii (g)

Most diagrams of particles on this page are second representations of their structure and land

EXAMPLES OF THE 3 PHYSICAL STATES OF MATTER

GASES e.chiliad. the air mixture around us (including the oxygen needed for combustion) and the loftier pressure steam in the boiler and cylinders of the steam locomotive. All of the gases in air are 'invisible', beingness colourless and transparent. Notation that the 'steam' y'all see exterior of a kettle or steam locomotive is really fine liquid droplets of water, formed from the expelled steam gas condensing when it meets the cold air � the 'country modify' of gas to liquid (same upshot in mist and fog formation).

LIQUIDS e.thou. water is the about common case, only so are, milk, hot butter, petrol, oil, mercury or alcohol in a thermometer.

SOLIDS eastward.g. stone, all metals at room temperature (except mercury), rubber of walking boots and the majority of physical objects around you. In fact most objects are useless unless they have a solid structure!

On this folio the basic concrete properties of gases, liquids and solids are described in terms of construction, particle movement (kinetic particle theory), effects of temperature and force per unit area changes, and particle models used to explain these properties and characteristics. Hopefully, theory and fact will match up to requite students a clear understanding of the material world around them in terms of gases, liquids and solids � referred to equally the three physical states of matter.

The changes of state known as melting, fusing, humid, evaporating, condensing, liquefying, freezing, solidifying, crystallising are described and explained with particle model pictures to assistance agreement. There is also a mention of miscible and immiscible liquids and explaining the terms volatile and volatility when applied to a liquid.

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i.1. The Iii States of Matter, gas�liquid�solid particle theory models

The three states of matter are solid, liquid and gas. Either melting and freezing tin can take identify at the melting point, whereas boiling and condensing accept identify at the boiling point. Evaporation can accept place at whatsoever temperature from a liquid surface. You tin can correspond the three states of matter with a simple particle model. In this model�diagrams, the particles are represented by modest solid inelastic spheres (electron structure is ignored).

Kinetic particle theory can assist to explain changes of state like melting, boiling, freezing and condensing. The corporeality of free energy needed to change state from solid to liquid or from liquid to gas depends on the forcefulness of the forces betwixt the particles of the substance.

These inter-particle forces may exist relatively weak intermolecular forces (intermolecular bonding) or strong chemical bonds (ionic, covalent or metallic). The nature of the particles involved depends on the blazon of chemic bonding and the structure of the substance. The stronger the attractive forces between the particles the higher the melting point and boiling point of the substance

WHAT ARE THE THREE STATES OF MATTER?
- Most materials can exist simply described as a gas, a liquid or a solid.
WHY ARE THEY Like WHAT THEY ARE?
- Simply knowing isn't enough, nosotros demand a comprehensive theory of gases, that tin can explain their behaviour and make predictions about what happens e.grand. if we change temperature or pressure.
HOW Tin can We EXPLAIN HOW THEY Conduct?
- We need a theoretical model due east.g. 'particle theory' that is supported past experimental evidence.
CAN PARTICLE MODELS Help U.s. UNDERSTAND THEIR Backdrop and CHARACTERISTICS?
- In a discussion, Aye!
WHY IS It Of import TO KNOW THE Backdrop OF GASES, LIQUIDS AND SOLIDS?
- It is of import in the chemical manufacture to know about the behaviour of gases, liquids and solids in chemical processes eastward.g. what happens to the different states with changes in temperature and pressure level.
What is the KINETIC PARTICLE THEORY of gases, liquids and solids?
- The kinetic particle theory of the states of matter is based on the idea of all materials existing as very very tiny particles which may be private atoms or molecules and the their interaction with each other either past standoff in gases or liquids or past vibration and chemic bonding in solids.
CAN WE Make PREDICTIONS BASED ON THEIR CHARACTERISTIC PROPERTIES?
- This folio introduces full general physical descriptions of substances in the simplest physical (not�chemic) nomenclature level i.e. is it a gas, liquid or a solid.
- BUT, this web folio besides introduces 'particle models' in which a small circle represents an cantlet or a molecule i.e. a particular particle or simplest unit of measurement of a substance.
- This section is quite abstract in a fashion because you are talking most particles you can't see as individually, y'all just the 'bulk' material and its physical character and properties.
Are there LIMITATIONS to the particle model?
- Well, yes! e.m.
- The particles are treated as simple inelastic spheres and just comport like infinitesimal snooker balls flying around, not quite true, but they do fly effectually not-stop at random!
- Although the particles are assumed to exist hard spheres and inelastic, in reality they are atoms, ions or molecules.
- Apart from lone atoms, they tin can exist all sorts of shapes and twist and curve on collision with other particles and when they react they split into fragments when bonds break.
- The simple model assumes no forces between the particles, only this is untrue, the model takes little account of the forces between the particles, fifty-fifty in gases you become very weak intermolecular bonding forces.
- The particle model takes no account of the actual size of the particles e.g. ions/molecules can be widely different in size due east.g. compare an ethene molecule with a poly(ethene) molecule!
- Neither does it take account of whatever space that may exist betwixt the particles.

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WHAT IS THE GASEOUS Land OF MATTER?

WHAT ARE THE Backdrop OF A GAS?

HOW DO GASEOUS PARTICLES Carry?

How does the kinetic particle theory of gases explicate the properties of gases?

A gas has no fixed shape or volume, but always spreads out to fill any container - the gas molecules volition diffuse into whatever space bachelor.

There are almost no forces of attraction between the particles then they are completely free of each other.

The particles are widely spaced and scattered and always moving rapidly at random throughout the container so there is no order in the system.

The particles move linearly and rapidly in all directions, and frequently collide with each other and the side of the container.

The standoff of gas particles with the surface of a container causes gas pressure level, on bouncing off a surface they exert a force in doing and then.
With increase in temperature, the particles movement faster every bit they gain kinetic free energy, the charge per unit of collisions between the particles themselves and the container surface increases and this increases gas force per unit area eg in a steam locomotive or the book of the container if it tin aggrandize eg like a balloon.

Using the particle model to explain the properties of a Gas

Gases accept a very low density (�light�) considering the particles are and then spaced out in the container (density = mass / volume).

Density order: solid > liquid >>> gases

Gases flow freely because there are no effective forces of allure between the gaseous particles � molecules.

Ease of flow order : gases > liquids >>> solids (no real flow in solid unless you finely pulverization it!)
Considering of this gases and liquids are described every bit fluids.

Gases have no surface, and no fixed shape or book , and because of lack of particle attraction, they always spread out and fill up whatever container (so gas volume = container volume).

Gases are readily compressed considering of the �empty� infinite betwixt the particles.
- Ease of compression order : gases >>> liquids > solids (almost incommunicable to shrink a solid)

Gas pressure level

When a gas is bars in a container the particles will cause and exert a gas pressure which is measured in atmospheres (atm) or Pascals (1.0 Pa = i.0 N/chiliad²), pressure is force/expanse i.east. the effect of all the collisions on the surface of the container.
- All particles have mass and their movement gives them kinetic energy and momentum.
- The gas pressure level is caused by the forcefulness created by millions of impacts of the tiny individual gas particles on the sides of a container.
- For example � if the number of gaseous particles in a container is doubled, the gas pressure is doubled because doubling the number of molecules doubles the number of impacts on the side of the container and then the total bear on forcefulness per unit of measurement area is also doubled.
  - This doubling of the particle impacts doubling the pressure is pictured in the ii diagrams beneath.

Upshot of temperature alter
If the volume of a sealed container is kept constant and the gas inside is heated to a higher temperature, the gas force per unit area increases.
- The reason for this is that every bit the particles are heated they gain kinetic energy and on boilerplate motility faster.
- Therefore they volition collide with the sides of the container with a greater strength of impact, so increasing the pressure.
  - There is also a greater frequency of collision with the sides of the container BUT this is a pocket-size factor compared to the effect of increased kinetic free energy and the increase in the average strength of affect.
- Therefore a stock-still amount of gas in a sealed container of abiding volume, the higher the temperature the greater the force per unit area and the lower the temperature the lesser the pressure level.
- For gas pressure�temperature calculations see Role 2 Charles's/Gay�Lussac'due south Police force

If the �container� volume can change, gases readily expand* on heating because of the lack of particle attraction, and readily contract on cooling.
- If there is no book brake the expansion on heating is much greater for gases than liquids or solids because there is no meaning attraction between gaseous particles. The increased average kinetic energy volition brand the gas pressure rising and and then the gas volition try to expand in volume if allowed to eastward.g. balloons in a warm room are significantly bigger than the same balloon in a cold room!

DIFFUSION in Gases:
- The natural rapid and random movement of the particles in all directions means that gases readily �spread� or diffuse.
  - Di ffusion continues until the concentrations are uniform throughout the container of gases, only ALL the particles keep moving with their always present kinetic free energy!

Diffusion is faster in gases than liquids where there is more than infinite for them to move (experiment illustrated below) and diffusion is negligible in solids due to the shut packing of the particles.
- Other evidence for random particle move including diffusion:
  - A long drinking glass tube (2�4 cm diameter) is filled at one end with a plug of cotton wool wool soaked in conc. hydrochloric acid sealed in with a rubber bung (for wellness and safety!) and the tube is kept perfectly still, clamped in a horizontal position. A like plug of conc. ammonia solution is placed at the other terminate. The soaked cotton wool wool plugs will give off fumes of HCl and NH₃ respectively, and if the tube is left undisturbed and horizontal, despite the lack of tube motility, e.g. NO shaking to mix and the absence of convection, a white cloud forms about ^ane/_threerd forth from the conc. hydrochloric acid tube stop.
    - Notation the rule: The smaller the molecular mass, the greater the average speed of the molecules (but all gases have the same boilerplate kinetic energy at the same temperature).

A demonstration of improvidence

A coloured gas , heavier than air (greater density), is put into the lesser gas jar and a second gas jar of lower density colourless air is placed over it separated with a glass cover. Diffusion experiments should be enclosed at abiding temperature to minimise disturbance by convection.

If the drinking glass cover is removed then (i) the colourless air gases diffuses down into the coloured brown gas and (ii) bromine diffuses up into the air. The random particle movement leading to mixing cannot be due to convection because the more dense gas starts at the bottom!

No 'shaking' or other means of mixing is required. The random move of both lots of particles is enough to ensure that both gases eventually become completely mixed by diffusion (spread into each other).

This is clear testify for diffusion due to the random continuous movement of all the gas particles and, initially, the internet movement of one blazon of particle from a higher to a lower concentration (' down a diffusion slope '). When fully mixed, no farther colour change distribution is observed BUT the random particle move continues! Run into too other evidence in the liquid section after the particle model for diffusion diagram beneath.

Heat conduction in gases
- All gases are very poor conductors of thermal energy, energy which is due to the kinetic free energy of the moving particles.
- Rut energy is transferred by 'hotter' higher kinetic energy gas particles colliding with 'cooler' lower kinetic free energy particles and so raising their kinetic free energy and spreading the heat energy.
- Even so, the density of gases is very low, so the density or rate of 'collision transfer' is quite low.
- Therefore gases are very good insulators due east.k. call back of their used in house insulation where air is trapped in various ways like cream or fibre glass loft insulation.
Electrical conduction in gases
- Electrical conduction requires the presence of complimentary IONS or free ELECTRONS i.e. particles that tin comport an electrical charge.
- Gases are poor conductors of electricity because they are commonly non in an ionic or ionised form.
- Withal, applying a very loftier potential departure of thousands of volts, specially with a low gas pressure, tin can cause the germination of gratis ions and electrons and electrical conduction tin can happen.
- Strip lighting and neon signs use this effect.

A note on 'forces'

Forces between particles are mentioned on this folio and some ideas will seem more abstract than others � but recollect about information technology ...
- A gas spreads everywhere in a given space, and then there can't be much attraction between the molecules/particles.
- Something must hold liquid molecules together or how can a liquid course from a gas?
- In fact between liquid molecules at that place are actually weak electric forces of attraction called intermolecular forces, but they can't exist strong enough to create a rigid solid structure.
- However, in solids, these forces must be stronger to create the rigid structure.
- Intermolecular forces are as well chosen 'intermolecular bonds' BUT these are not the same as covalent, ionic or metal bonds and they are much weaker than these true chemic bonds.

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WHAT IS THE LIQUID STATE OF Thing?

WHAT ARE THE Properties OF A LIQUID?

HOW DO LIQUID PARTICLES Deport?

How does the kinetic particle theory of liquids explain the properties of liquids?

A liquid has a stock-still book at a given temperature but its shape is that of the container which holds the liquid.

In that location are much greater forces of allure between the particles in a liquid compared to gases, but not quite every bit much equally in solids and the particles are sufficiently free to move past each other.

If there were no intermolecular forces, liquids could not exist!

The particles are quite close together but nevertheless bundled at random throughout the container due to their abiding random movement, at that place is a picayune shut range order as you can get clumps of particles clinging together temporarily (as in the diagram in a higher place).
Likewise every bit moving rapidly in all directions, they collide more frequently with each other than in gases due to shorter distances between particles � much greater density - particles closer together.

With increment in temperature, the particles motility faster as they proceeds kinetic energy, so increased collision rates, increased collision energy, increased rates of particle diffusion, expansion leading to subtract in density.

Using the particle model to explain the properties of a Liquid

Liquids have a much greater density than gases (�heavier�) because the particles are much closer together because of the attractive forces.

Nigh liquids are simply a little less dense than when they are solid

Water is a curious exception to this general rule, which is why ice floats on water.

Liquids usually flow freely despite the forces of allure between the particles but liquids are not as �fluid� as gases.

Note 'gummy' or viscid liquids have much stronger attractive forces between the molecules BUT not strong enough to form a solid.

Liquids have a surface , and a stock-still volume (at a particular temperature) because of the increased particle attraction, merely the shape is not fixed and is merely that of the container itself.

Liquids seem to have a very weak 'skin' surface result which is acquired by the majority molecules alluring the surface molecules disproportionately.

Liquids are not readily compressed because there is so little �empty� infinite betwixt the particles, and so increase in pressure has only a tiny effect on the volume of a solid, and you need a huge increase in pressure level to see whatever real contraction in the book of a liquid.

Liquids will expand on heating merely nothing like every bit much as gases, but more solids, because of the greater particle attraction restricting the expansion (will contract on cooling).
- Notation: When heated, the liquid particles gain kinetic free energy and hit the sides of the container more than frequently, and more than significantly, they striking with a greater force, so in a sealed container the pressure produced in a liquid can be considerable!

DIFFUSION : The natural rapid and random movement of the particles means that liquids �spread� - lengthened. Diffusion is much slower in liquids compared to gases because in that location is less infinite for the particles to move in and more �blocking� collisions happen.
- Just dropping lumps/granules/powder of a soluble solid (preferably coloured!) will resulting in a dissolving followed by an observable improvidence effect.
- Again, the net flow of dissolved particles will be from a higher concentration to a lower concentration until the concentration is uniform throughout the container.

Diffusion in liquids � evidence for random particle movement in liquids :
- If coloured crystals of eastward.g. the highly coloured salt crystals of potassium manganate(Seven) are dropped into a beaker of h2o and covered at room temperature.

Heat conduction in liquids

Almost liquids are poor conductors of thermal energy, free energy which is due to the kinetic energy of the moving particles.
Rut energy is transferred by 'hotter' higher kinetic free energy liquid particles colliding with 'cooler' lower kinetic energy particles so raising their kinetic energy and spreading the heat energy.
However, the density of liquids is much greater than gases (particles much closer together), so the density or charge per unit of 'collision transfer' is much higher, so liquids are ameliorate heat conductors than gases.
Liquid metals are very good heat conductors because of the freely moving electrons that tin can carry the kinetic free energy rapidly through the liquid. For more details run into 'metal construction'.

Electrical conduction in liquids

Electric conduction requires the presence of complimentary IONS or gratuitous ELECTRONS i.eastward. particles that tin can carry an electrical charge.
Most liquids are poor conductors of electricity (good insulators), only there are important exceptions.
For example, if a liquid contains ions e.thousand. salt solutions, so electrical conduction can have identify
Liquid metals are very good electrical conductors because of the freely moving electrons that can acquit the electric electric current rapidly through the liquid metal.
For more details see 'electrolysis' and 'metal construction'.

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WHAT IS THE SOLID STATE OF MATTER?

WHAT ARE THE PROPERTIES OF A SOLID?

HOW DO SOLID PARTICLES BEHAVE?

How does the kinetic particle theory of solids explicate the backdrop of solids?

A solid has a fixed book and shape at a item temperature unless physically subjected to some strength.

The greatest forces of attraction are between the particles in a solid and they pack together as tightly equally possible in a neat and ordered system called a lattice.

The particles are besides strongly held together to allow movement from place to place only the particles vibrate about their position in the structure.

With increase in temperature, the particles vibrate faster and more than strongly equally they gain kinetic energy, so the vibration increases causing expansion.

More on the kinetic particle theory of an ideal gas

Using the particle model to explain the properties of a Solid

Solids have the greatest density (�heaviest�) because the particles are closest together.

Solids cannot menstruum freely like gases or liquids considering the particles are strongly held in fixed positions.

Solids take a fixed surface and volume (at a particular temperature) because of the strong particle attraction.

Solids are extremely difficult to compress because there is no real �empty� infinite between the particles, so increase in pressure level has virtually no outcome on the volume of a solid.

Solids volition expand a little on heating but nothing like as much as liquids because of the greater particle attraction restricting the expansion and causing the contraction occurs on cooling.
- The expansion is caused by the increased kinetic energy of particle vibration, forcing them further apart causing an increment in book and corresponding decrease in density.
- Although t he expansion of a solid is due to the higher average kinetic energy of the particles and the more energetic vibrations, they are still held together by the intermolecular bonding forces (or much stronger strong ionic or covalent bonds), which restricts the expansion - this is not office of the kinetic particle theory!

Diffusion is virtually impossible in solids because the particles are besides closely packed and strongly held together in a lattice. The immobile particles cannot movement around because there is no random movement into �empty space� for them to movement through.

Its quite a unlike situation in gases and liquids where diffusion readily takes place because of the freedom of the particles to move around at random and 'fustigate' each other aside!

Rut conduction in solids

Apart from metals, virtually solids are poor conductors of heat energy, energy which is due to the kinetic energy of the vibrating particles in the crystal construction � remember, dissimilar gases and liquids, the particles can't motility around, they merely vibrate most a stock-still bespeak.
Rut energy is transferred by 'hotter' higher kinetic free energy vibrating particles colliding against 'libation' lower kinetic energy vibrating particles so raising their kinetic energy and spreading the heat energy through the solid structure.
The density of solids and order of particles is are greater than liquids (particles closest together), so the density or charge per unit of 'collision transfer' vibration is much higher, and so solids are improve heat conductors than liquids (and much greater than gases).
Still, although most non-metal solids are poor heat conductors, metals are exceptionally good heat conductors because of the freely moving electrons that can acquit the kinetic free energy chop-chop through the crystal structure.
For more details see 'metal structure'.

Electrical conduction in solids

Electrical conduction requires the presence of free IONS or free ELECTRONS i.e. particles that can carry an electrical charge inside a solid structure. Which of course is impossible in most solids (except metals) because ALL particles tin can't move around, then even solid ionic compounds cannot conduct electricity.
Most not-metal solids are poor conductors of electricity (good insulators), simply at that place are important exceptions.
All metals are relatively good electrical conductors because of the freely moving electrons that can carry the electrical current rapidly through the liquid metal. For more details see 'metallic construction'.
Graphite and graphene, forms (allotropes) of the not�metal element carbon, are electrical conductors due to gratuitous moving electrons in the solid construction, a rare exception of conducting solids autonomously from metals.

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two. Changes of Country for gas <=> liquid <=> solid

You need to be able to predict the state of a substance at different temperatures given appropriate information.

FREEZING

MELTING

SUBLIMING -the contrary is degradation or 'reverse sublimation'

Humid or EVAPORATING

SUMMARY of the CHANGES of STATE between a gas, liquid and solid

All mass conserved in these PHYSICAL CHANGES

CONDENSING

These are Not chemical changes !

A change of state ways an interconversion between two states of matter, namely gas <=> liquid <=> solid

A 'triangular' summary of important country changes is illustrated in a higher place.

due east.g. solid ==> liquid is melting or fusing

liquid ==> gas/vapour (vapor) is boiling, evaporation or vapourisation (vaporisation)

and the reverse processes

gas/vapour (vapor) ==> liquid is condensation, liquefaction/liquefying

liquid ==> solid is freezing, solidifying or crystallising

and in that location is also

solid ==> gas is sublimation

Nosotros can use the country particle models and diagrams to explain changes of state and the free energy changes involved.

These are Non chemical changes Simply Physical CHANGES, due east.k. the water molecules H₂O are just the same in ice, liquid water, steam or water vapour. What is unlike, is how they are arranged, and how strongly they are held together by intermolecular forces in the solid, liquid and gaseous states.

2a. Evaporation and Humid (liquid to gas)

Explained using the kinetic particle theory of gases and liquids

Evaporation is when particles of a liquid escape to form a gas or vapour i.e. water evaporating into the air.
Considering of random collisions, the particles in a liquid have a variety of speeds and kinetic energies. On heating, particles proceeds kinetic energy and move faster and are more able to overcome the intermolecular forces between the molecules i.e. some particles will have enough kinetic energy to overcome the attractive forces holding the particles together in the bulk liquid.
- Fifty-fifty without farther heating, evaporation occurs all the time from volatile liquids, but it is withal the higher kinetic free energy particles that tin overcome the attractive forces betwixt the molecules in the bulk of the liquid and escape from the surface into the surrounding air.

In evaporation and boiling (both are vaporisation) it is the highest kinetic free energy molecules that tin �escape� from the attractive forces of the other liquid particles.
- The particles lose whatever order and become completely free to grade a gas or vapour.

Energy is needed to overcome the attractive forces between particles in the liquid and is taken in from the surroundings.
- In boiling, estrus energy must be continually supplied east.grand. from an electrical heating element or Bunsen burner etc.
- In the instance of evaporation, the heat is taken from the liquid, so an evaporating liquid cools - the lower speed/kinetic energy particles are left behind.

This ways heat is taken in, and then evaporation and boiling are endothermic processes (ΔH +ve).

If the temperature is loftier enough humid takes place and bubbling of gas form in the bulk liquid � something you lot don't come across in evaporation, because that can only occur on the surface of a liquid.

Boiling is rapid vapourisation anywhere in the bulk liquid and at a fixed temperature chosen the boiling point and requires continuous addition of heat.
- B oiling point depends on the ambient pressure, the lower the gas pressure to a higher place the liquid, the lower the boiling point of the liquid.
- This is why tea brewed on the summit of high mountain isn't quite as good as at sea level, the water boils at a lower temperature and doesn't excerpt substances from the tea leaves equally efficiently!
- In the past, measuring the boiling point of water was used to guess the summit of land above sea level!

The rate of boiling is limited by the rate of heat transfer into the liquid.

Evaporation takes place more slowly than boiling at whatsoever temperature between the melting point and humid point, and only from the surface, and results in the liquid condign libation due to loss of higher kinetic energy particles.

Factors affecting the rate of evaporation of a liquid.

The college the temperature of the liquid, the faster it evaporates, because more than particles accept sufficient kinetic energy to overcome the intermolecular forces of the bulk liquid and can escape from the liquid surface.
The larger the expanse of given volume of liquid, the faster it evaporates, because there is a greater probability of particles escaping.
The greater the airflow over a liquid the faster it evaporates considering its stops a build�up of vapour particles which may hit the surface and condense! The airflow lowers the concentration of evaporated particles by sweeping them away and then more readily replaced past freshly evaporated particles.
Please note that the all-time conditions for drying washing are a warm sunny day, a good breeze, and spreading the clothes out as much every bit possible to increase their surface surface area (I get told off near this i!).

More details on the due east nergy changes for these concrete changes of state for a range of substances are dealt with in a section of the Energetics Notes .

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2b. Condensing (gas to liquid) � the process of condensation

Explained using the kinetic particle theory of gases and liquids

On cooling, gas particles lose kinetic energy, they wearisome downwardly and somewhen become attracted together via intermolecular forces to course a liquid i.due east. they haven't enough kinetic free energy to remain gratuitous in the gaseous country.

There is an increment in order as the particles are much closer together and can form clumps of molecules.

The process requires heat to be lost to the surroundings i.e. heat given out, so condensation is exothermic (ΔH �ve).
- This is why steam has such a scalding result, its not merely hot, simply you go actress heat transfer to your skin due to the exothermic condensation on your surface!

Factors affecting the charge per unit of condensation of a gas�vapour

The lower the temperature of the gas the faster it condenses because the particles on average have less kinetic energy to overcome the attractive intermolecular forces i.e. they gas particles are more probable to aggregate into drops of liquid.
The colder the surface the gas condenses on, the faster the estrus transfer to reduce the kinetic energy of the gas particles, so the faster the gas/vapour can condense.
The higher the concentration of vapour in air, the faster condensation can take identify. The particles are closer together and more than chance of combining to form liquid aerosol.

2c. Distillation � the process of distilling a liquid

Elementary and partial distillation involve the processes of humid and condensation and are described on the Elements, Compounds and Mixtures Part 2 page, where other methods of separation are also described.

The process of distillation involves boiling (liquid ==> gas/vapor) and the reverse process of condensation (gas/vapour ==> liquid)

2d. Melting (solid to liquid)

Explained using the kinetic particle theory of liquids and solids

When a solid is heated the particles vibrate more strongly every bit they gain kinetic energy and the particle attractive forces are weakened.

Somewhen, at the melting indicate, the attractive forces are too weak to concord the particles in the structure together in an ordered style and so the solid melts.
- Note that the intermolecular forces are even so there to concur the bulk liquid together � but the effect is not strong enough to form an ordered crystal lattice of a solid.

The particles get costless to move around and lose their ordered arrangement.

Energy is needed to overcome the attractive forces and give the particles increased kinetic energy of vibration.

So heat is taken in from the environment and melting is an endothermic process (ΔH +ve).

Free energy changes for these physical changes of state for a range of substances are dealt with in a section of the Energetics Notes.

2e. Freezing (liquid to solid)

Explained using the kinetic particle theory of liquids and solids

On cooling, liquid particles lose kinetic energy and so can become more strongly attracted to each other.

When the temperature is low plenty, the kinetic free energy of the particles is insufficient to forestall the particle attractive forces causing a solid to form.

Eventually at the freezing indicate the forces of allure are sufficient to remove any remaining freedom of movement (in terms of one place to another) and the particles come up together to form the ordered solid arrangement (though the particles still take vibrational kinetic energy.

Since heat must be removed to the surroundings, so strange equally it may seem, freezing is an exothermic procedure (ΔH �ve).

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2f . Cooling and Heating Curves and the comparative energy changes for changes of land: gas <=> liquid <=> solid

2f(i) Cooling bend : What happens to the temperature of a substance if it is cooled from the gaseous country to the solid land?

Note the temperature stays constant during the state changes of condensing at temperature Tc, and freezing/solidifying at temperature Tf. This is because all the heat energy removed on cooling at these temperatures (the latent heats or enthalpies of state modify), allows the strengthening of the inter�particle forces (intermolecular bonding) without temperature fall. The rut loss is compensated by the exothermic increased intermolecular forcefulness attraction. In between the 'horizontal' state change sections of the graph, you can see the energy 'removal' reduces the kinetic free energy of the particles, lowering the temperature of the substance. See section 2. for detailed description of the state changes.

A cooling bend summarises the changes:

gas ==> liquid ==> solid

For each change of state, free energy must be removed, known equally the 'latent heat'

Actual free energy values for these physical changes of land for a range of substances are dealt with in more than detail in the Energetics Notes .

2f(ii) Heating bend : What happens to the temperature of a substance if it is heated from the solid state to the gaseous country?

Notation the temperature stays constant during the country changes of melting at temperature Tm and boiling at temperature Tb. This is because all the energy absorbed in heating at these temperatures (the latent heats or enthalpies of state alter), goes into weakening the inter�particle forces (intermolecular bonding) without temperature rise The heat gain equals the endothermic/heat absorbed energy required to reduce the intermolecular forces. In between the 'horizontal' land change sections of the graph, you can encounter the free energy input increases the kinetic free energy of the particles and raising the temperature of the substance. See section ii. for detailed clarification of the land changes.

A heating curve summarises the changes:

solid ==> liquid ==> gas

For each modify of state, energy must be added, known every bit the 'latent rut'

Bodily free energy values for these physical changes of country for a range of substances are dealt with in more item in the Energetics Notes .

SPECIFIC LATENT HEATS - refer to diagram below

The latent heat for the country changes solid <=> liquid is called the specific latent rut of fusion (for melting or freezing).

The latent heat for the state changes liquid <=> gas is called the specific latent heat of vaporisation (for condensing, evaporation or humid)

For more on latent oestrus meet my physics notes on specific latent heat

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2g. Sublimation

Explained using the kinetic particle theory of gases and solids

Sublimation:
- This is when a solid, on heating, straight changes into a gas without melting, AND the gas on cooling re�forms a solid directly without condensing to a liquid. Sublimation normally just involves a physical change BUT its non always that simple (see ammonium chloride!).

Theory in terms of particles:

When the solid is heated the particles vibrate with increasing force from the added thermal energy.
- If the particles have enough kinetic energy of vibration to partially overcome the particle�particle bonny forces you would await the solid to melt.
- Even so, if the particles at this betoken have plenty energy at this point that would take led to boiling, the liquid volition NOT form and the solid turns direct into a gas.
  - Overall endothermic modify, free energy captivated and 'taken in' to the system.
On cooling, the particles move slower and take less kinetic energy.
- Eventually, when the particle kinetic energy is low enough, information technology will allow the particle�particle attractive forces to produce a liquid.
- BUT the free energy may be low enough to permit directly germination of the solid, i.eastward. the particles practice NOT have plenty kinetic energy to maintain a liquid state!
  - Overall exothermic change, energy released and 'given out' to the surroundings.

Examples:

Fifty-fifty at room temperature bottles of solid iodine bear witness crystals forming at the top of the canteen in a higher place the solid. The warmer the laboratory, the more crystals form when it cools down at night!

The formation of a particular course of frost involves the direct freezing of h2o vapour (gas). Frost tin likewise evaporate directly dorsum to water vapour (gas) and this happens in the 'dry' and extremely cold winters of the Gobi Desert on a sunny day.

Solid carbon dioxide (dry out ice)
is formed on cooling the gas down to less than �78^oC. On warming information technology changes directly to a very cold gas!, condensing any water vapour in the air to a 'mist', hence its use in stage effects.
- CO_{two (due south)} CO_{2 (g)} (physical alter only)

On heating strongly in a test tube, white solid ammonium chloride, decomposes into a mixture of two colourless gases ammonia and hydrogen chloride. On cooling the reaction is reversed and solid ammonium chloride reforms at the cooler tiptop surface of the exam tube.

Ammonium chloride + heat energy ammonia + hydrogen chloride
NH_ivCl_(south) NH_3(thousand) + HCl_(g)
This involves both chemic and physical changes and is so is more complicated than examples 1. to 3. In fact the ionic ammonium chloride crystals change into covalent ammonia and hydrogen chloride gases which are naturally far more volatile (covalent substances generally have much lower melting and boiling points than ionic substances).

The liquid particle moving picture does non figure here, but the other models fully apply apart from state changes involving liquid formation. GAS particle model and SOLID particle model links.

Delight NOTE, At a higher level of study, you demand to study the g�50�s phase diagram for water and the vapour pressure curve of ice at particular temperatures. For example, if the ambience vapour pressure is less than the equilibrium vapour pressure at the temperature of the water ice, sublimation can readily take identify. The snow and water ice in the colder regions of the Gobi Desert practise not cook in the Sun, they just slowly 'sublimely' disappear!

The germination of hoar frost - the reverse of sublimation

Frost is a thin layer of ice on a solid surface.

Hoar frost forms directly from h2o vapour in air higher up 0^oC, coming in contact with a solid surface whose temperature is below freezing (<0^oC).

The h2o vapor changes direct from gas (vapour) to solid (ice) every bit information technology comes into contact with the solid surface.

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ii h. More on the latent heat changes of physical changes of country

Changes of physical state i.e. gas <==> liquid <==> solid are also accompanied by free energy changes.

To melt a solid, or boil/evaporate a liquid, rut free energy must be absorbed or taken in from the surround, so these are endothermic energy changes. The system is heated to effect these changes.

To condense a gas, or freeze a solid, heat energy must be removed or given out to the environs, so these are exothermic energy changes. The system is cooled to effect these changes.

Generally speaking, the greater the forces between the particles, the greater the energy needed to effect the state change AND the higher the melting betoken and boiling point.

A comparison of free energy needed to melt or boil different types of substance

(This is more for advanced level students)

The heat energy change involved in a land change can be expressed in kJ/mol of substance for a fair comparison.

In the tabular array below

ΔH_melt is the energy needed to melt one mole of the substance (formula mass in g).

ΔH _vap is the free energy needed to vaporise past evaporation or humid 1 mole of the substance (formula mass in g).

These are the latent heats required to change the physical land of a substance.

For simple pocket-size covalent molecules, the energy captivated by the material is relatively small to melt or vaporise the substance and the bigger the molecule the greater the inter�molecular forces.

These forces are weak compared to the chemic bonds holding atoms together in a molecule itself.

Relatively low energies are needed to melt or vapourise them.

These substances take relatively low melting points and humid points.

Covalent Bonding � pocket-sized uncomplicated molecules

For strongly bonded 3D networks e.g.

(i) an ionically bonded lattice of ions (ionic bonding ),

(2) a covalently bonded lattice of atoms (covalent bonding � giant covalent structures ),

(iii) and a metal lattice of ions and gratuitous outer electrons (metallic bonding ),

the structures are much stronger in a continuous way because of the continuous chemical bonding throughout the construction.

Consequently, much greater energies are required to melt or vaporise the textile.

This is why they have then much higher melting points and boiling points.

Substance formula Type of bonding, structure and bonny forces operating Melting signal Yard (Kelvin) = ^oC + 273 Energy needed to melt substance Boiling point K (Kelvin) = ^oC + 273 Energy needed to boil substance

methyl hydride CH₄ small covalent molecule � very weak intermolecular forces 91K/�182^oC 0.94kJ/mol 112K/�161^oC 8.2kJ/mol

ethanol ('alcohol') C_twoH₅OH larger covalent molecule than methane, greater, but still weak intermolecular forces 156K/�117^oC 4.6kJ/mol 352K/79^oC 43.5kJ/mol

sodium chloride Na⁺Cl^� ionic lattice, very strong 3D ionic bonding due to attraction between (+) and (�) ions 1074K/801^oC 29 kJ/mol 1740K/1467^oC 171 kJ/mol

iron Fe potent 3D bonding by attraction of metal ions (+) with free outer electrons (�) 1808K/1535^oC fifteen.4kJ/mol 3023K/2750^oC 351kJ/mol

silicon dioxide (silica) SiO₂ giant covalent structure, strong continuous 3D bond network 1883K/1610^oC 46.4kJ/mol 2503K/2230^oC 439kJ/mol

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3. Dissolving solids, solutions and miscible/immiscible liquids

3a. WHAT HAPPENS TO PARTICLES WHEN A SOLID DISSOLVES IN A LIQUID SOLVENT?

What practise the words SOLVENT, SOLUTE and SOLUTION mean?
When a solid (the solute) dissolves in a liquid (the solvent) the resulting mixture is called a solution.
- In general: solute + solvent ==> solution

3b. WHAT HAPPENS TO PARTICLES WHEN TWO LIQUIDS COMPLETELY MIX WITH EACH OTHER?

WHAT DOES THE Discussion MISCIBLE MEAN?

Using the particle model to explain miscible liquids.

If two liquids completely mix in terms of their particles, they are called miscible liquids because they fully dissolve in each other. This is shown in the diagram beneath where the particles completely mix and move at random. The process can exist reversed by fractional distillation.

3c. WHAT HAPPENS TO PARTICLES WHEN Ii LIQUIDS Practice Not MIX WITH EACH OTHER?

WHAT DOES THE WORD IMMISCIBLE Mean?

WHY Practise THE LIQUIDS NOT MIX?
Using the particle model to explain immiscible liquids.
If the two liquids do NOT mix, they grade two separate layers and are known as immiscible liquids, illustrated in the diagram below where the lower purple liquid will be more dense than the upper layer of the green liquid.
- You lot can split these 2 liquids using a separating funnel.
- The reason for this is that the interaction between the molecules of one of the liquids lone is stronger than the interaction between the 2 dissimilar molecules of the dissimilar liquids.
- For example, the strength of attraction between h2o molecules is much greater than either oil�oil molecules or oil�water molecules, so ii separate layers grade because the h2o molecules, in terms of free energy change, are favoured past 'sticking together'.

3d. How a separating funnel is used

1. The mixture is put in the separating funnel with the stopper on and the tap closed and the layers left to settle out.

ii. The stopper is removed, and the tap is opened then that you can carefully run the lower grey layer off offset into a beaker.

3. The tap is and then closed once again, leaving behind the upper yellowish layer liquid, so separating the two immiscible liquids.

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State changes: 2a evaporation and boiling, 2b condensation, 2c distillation, 2d melting, 2e freezing, 2f cooling and heating curves and relative free energy changes, 2g sublimation * 3. Dissolving, solutions. miscible/immiscible liquids Humid * point * Brownian motion * Changes of land * Condensing * Cooling curve * Diffusion * Dissolving * Evaporation * Freezing * point * Gas particle picture * Heating curve * Liquid particle picture * Melting * point * miscible/immiscible liquids * Properties of gases * Backdrop of liquids * Properties of solids * solutions * sublimation * Solid particle picture * GCSE/IGCSE multiple choice QUIZ on states of matter gases liquids solids do revision questions Revision notes on particle models and backdrop of gases, liquids and solids KS4 Science GCSE/IGCSE/O level Chemical science Information on particle models and properties of gases, liquids and solids for revising for AQA GCSE Science, Edexcel Science chemistry IGCSE Chemistry notes on particle models and properties of gases, liquids and solids OCR 21st Century Science, OCR Gateway Science notes on particle models and properties of gases, liquids and solids WJEC gcse science chemistry notes on particle models and backdrop of gases, liquids and solids CIE O Level chemistry CIE IGCSE chemistry notes on particle models and properties of gases, liquids and solids CCEA/CEA gcse science chemistry (revise courses equal to U.s. course 8, grade nine class 10) science chemistry courses revision guides caption chemic equations for particle models and properties of gases, liquids and solids educational videos on particle models and backdrop of gases, liquids and solids guidebooks for revising particle models and properties of gases, liquids and solids textbooks on particle models and properties of gases, liquids and solids state changes & particle model for AQA AS chemistry, state changes & particle model for Edexcel A level As chemistry, land changes & particle model for A level OCR As chemistry A, state changes & particle model for OCR Salters AS chemistry B, country changes & particle model for AQA A level chemistry, state changes & particle model for A level Edexcel A level chemistry, country changes & particle model for OCR A level chemistry A, state changes & particle model for A level OCR Salters A level chemical science B land changes & particle model for US Honours grade 11 grade 12 state changes & particle model for pre-university chemistry courses pre-university A level revision notes for country changes & particle model A level guide notes on state changes & particle model for schools colleges academies scientific discipline course tutors images pictures diagrams for state changes & particle model A level chemistry revision notes on state changes & particle model for revising module topics notes to help on understanding of land changes & particle model university courses in science careers in scientific discipline jobs in the industry laboratory banana apprenticeships technical internships Usa US grade 11 grade 11 AQA A level chemistry notes on state changes & particle model Edexcel A level chemistry notes on land changes & particle model for OCR A level chemistry notes WJEC A level chemical science notes on state changes & particle model CCEA/CEA A level chemistry notes on state changes & particle model for university entrance examinations describe some limitations of the particle model for gases, liquids and solids

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How Does The Kinetic Energy (Movement) Of Particles Change Throughout Lab?

2e. Freezing (liquid to solid)

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ii h. More on the latent heat changes of physical changes of country Changes of physical state i.e. gas <==> liquid <==> solid are also accompanied by free energy changes. To melt a solid, or boil/evaporate a liquid, rut free energy must be absorbed or taken in from the surround, so these are endothermic energy changes. The system is heated to effect these changes. To condense a gas, or freeze a solid, heat energy must be removed or given out to the environs, so these are exothermic energy changes. The system is cooled to effect these changes. Generally speaking, the greater the forces between the particles, the greater the energy needed to effect the state change AND the higher the melting betoken and boiling point. A comparison of free energy needed to melt or boil different types of substance (This is more for advanced level students) The heat energy change involved in a land change can be expressed in kJ/mol of substance for a fair comparison. In the tabular array below ΔH_melt is the energy needed to melt one mole of the substance (formula mass in g). ΔH _vap is the free energy needed to vaporise past evaporation or humid 1 mole of the substance (formula mass in g). These are the latent heats required to change the physical land of a substance. For simple pocket-size covalent molecules, the energy captivated by the material is relatively small to melt or vaporise the substance and the bigger the molecule the greater the inter�molecular forces. These forces are weak compared to the chemic bonds holding atoms together in a molecule itself. Relatively low energies are needed to melt or vapourise them. These substances take relatively low melting points and humid points. Covalent Bonding � pocket-sized uncomplicated molecules For strongly bonded 3D networks e.g. (i) an ionically bonded lattice of ions (ionic bonding ), (2) a covalently bonded lattice of atoms (covalent bonding � giant covalent structures ), (iii) and a metal lattice of ions and gratuitous outer electrons (metallic bonding ), the structures are much stronger in a continuous way because of the continuous chemical bonding throughout the construction. Consequently, much greater energies are required to melt or vaporise the textile. This is why they have then much higher melting points and boiling points.
Substance	formula	Type of bonding, structure and bonny forces operating	Melting signal Yard (Kelvin) = ^oC + 273	Energy needed to melt substance	Boiling point K (Kelvin) = ^oC + 273	Energy needed to boil substance
methyl hydride	CH₄	small covalent molecule � very weak intermolecular forces	91K/�182^oC	0.94kJ/mol	112K/�161^oC	8.2kJ/mol
ethanol ('alcohol')	C_twoH₅OH	larger covalent molecule than methane, greater, but still weak intermolecular forces	156K/�117^oC	4.6kJ/mol	352K/79^oC	43.5kJ/mol
sodium chloride	Na⁺Cl^�	ionic lattice, very strong 3D ionic bonding due to attraction between (+) and (�) ions	1074K/801^oC	29 kJ/mol	1740K/1467^oC	171 kJ/mol
iron	Fe	potent 3D bonding by attraction of metal ions (+) with free outer electrons (�)	1808K/1535^oC	fifteen.4kJ/mol	3023K/2750^oC	351kJ/mol
silicon dioxide (silica)	SiO₂	giant covalent structure, strong continuous 3D bond network	1883K/1610^oC	46.4kJ/mol	2503K/2230^oC	439kJ/mol