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The Particle model of matter

Phases of matter

Melting, boiling, evaporation, sublimation

Diffusion

Brownian motion

Pressure and volume changes with temp

Celsius and Kelvin scale

Absolute zero

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EVIDENCE THAT MATTER CONSISTS OF SMALLER PARTICLES

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EVIDENCE THAT MATTER CONSISTS OF SMALLER PARTICLES

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EVAPORATION

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Crystallization = the addition of new atoms or ions into a repeating arrangement called a crystal lattice.

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Crystallization = the addition of new atoms or ions into a repeating arrangement called a crystal lattice.

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A saturated solution of potassium ferricyanide evaporates from a watch-glass at room temperature. Petroleum jelly was applied to the rim of the watch-glass. I used the Lapse-It app on my Android smartphone to take one frame every three minutes for about 29 hours.

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DIFFUSION ILLUSTRATES = intermingling of substances by the natural movement of their particles

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DIFFUSION ILLUSTRATES = intermingling of substances by the natural movement of their particles

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Potassium Permanganate Diffusion (Time Lapse)

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Matter:
Anything that takes up space and has mass.

Temperature:
A measure of the average kinetic energy of the particles in a system.

Melting point:
The temperature at which a solid becomes a liquid at a fixed pressure, usually standard pressure.

Boiling point:
The temperature at which a liquid becomes a gas at a fixed pressure, under atmospheric conditions.

Freezing point:
The temperature at which a liquid becomes a solid at atmospheric pressure.

Diffusion:
The spontaneous moving mixing and spreading of one substance through another substance from a region of high concentration to a region of low concentration, until the particles are evenly spread.

Brownian motion
The continuous movement of particles in liquids or gases by the impact of moving liquid or gas molecules striking the particles.

Absolute Zero
Temperature at which the particles stop moving in an object.

Evaporation:
This is the loss of molecules from the surface of a liquid into the gas phase. Evaporation is a slow process, does not produce bubbles, and results in cooling.

Boiling:
Boiling is the phase change from liquid to gas which happens faster than evaporation, produces lots of bubbles, and does not result in cooling.

Atom:
The smallest part of an element having the chemical properties of the element.

Element:
An element cannot be broken down into anything simpler by chemical means.

Compound:
A compound is made up of two or more DIFFERENT elements chemically combined (joined together).

Pressure:
Force per unit area.

Mass:
The amount of matter in an object.

Density:
Mass per unit volume.

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What does the particle model of matter teach us?

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What does the particle model of matter teach us?

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Four important aspects of matter:

TINY PARTICLES - All matter is made up of particles that are incredibly small - much too small to see with the naked eye. The particles can be atoms or combinations of atoms that are bonded.

FORCES - There are forces between the particles.

MOTION - These particles are in constant and random motion. The higher the temperature of the substance, the higher the speed of the particles.

SPACES BETWEEN PARTICLES - The spaces between the particles are empty. They contain nothing at all - not even air!

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Definition:
Temperature is a measure of the average kinetic energy of the particles in a system.

The coldest possible temperature is when the molecules in a system are not moving at all. This happens at -273 oC. (ABSOLUTE ZERO)

The Kelvin Scale

This temperature scale uses divisions which are the same as the Celsius scale but instead of zero being the temperature of melting ice (0 oC) it is instead the coldest possible temperature: Absolute Zero (0 K).
T K = T o C + 273

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Complete the table ABOVE:

https://youtu.be/Xy2qVIhTtG8

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ENERGY EXCHANGE INVOLVED IN PHASE CHANGES

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ENERGY EXCHANGE INVOLVED IN PHASE CHANGES

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Looking at the effect of adding or removing heat from different phases of matter:

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Substances with very weak forces between their molecules will turn directly into the gas phase from solid phase upon absorbing heat, due to them requiring very little energy to overcome these weak intermolecular forces between its molecules.

DEFINITIONS:
Sublimation = The transition of a substance directly from the solid to the gas state, without passing through the liquid state.

Deposition = The reverse process of sublimation in which a substance passes directly from a gas to a solid phase.

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Sublimation - Why do mothballs disappear over time? | #aumsum #kids #science #education #children

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Chemistry experiment 47 - Sublimation of Iodine

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Dry ice is solid carbon dioxide

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Ice, Ice, Bubble: A Dry Ice Sublimation Demonstration

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Boiling point and Melting point-Physical Properties

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Latent Heat (“Hidden” heat for phase changes)

When a phase change is happening (e.g melting) the temperature stays more or less constant despite the fact that energy is being added or removed from the system. This energy is called “latent heat” because it seems to disappear.

This release of energy as steam condenses is why a scald from steam can cause such a terrible wound. All the energy released damages the skin and flesh below. Steam is therefore very dangerous.

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The heating curve of water shows latent heat

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The heating curve of water shows latent heat

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Even though heat is added to water at constant rate, temperature of the water does not increase at a constant rate.

Heat and temperature are not directly proportional to each other.

Heat and temperature are not the same concepts.

Heat = TRANSFER of thermal energy from a hot to a cold substance.

Temperature = AVERAGE KINETIC ENERGY of the particles in a substance.

The plateaus on the heating curve shows the latent heat of phase changing.

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BOILING POINT CHANGES WITH ALTITUDE DUE TO CHANGE IN PRESSURE

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BOILING POINT CHANGES WITH ALTITUDE DUE TO CHANGE IN PRESSURE

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The boiling point of water at sea level is 100 oC.

The boiling point of water on top of Mount Everest is only 70 oC.

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Boiling Water On Mount Everest! | Earth Lab

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CHANGING PRESSURE CHANGES BOILING POINT OF A SUBSTANCE

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CHANGING PRESSURE CHANGES BOILING POINT OF A SUBSTANCE

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Higher pressure gives a higher boiling point.  Water boils at lower temperature the higher the altitude.

PRESSURE OF GASES

The pressure of a gas results from particles colliding with the sides of the container.

Therefore the greater the number of collisions and the greater the average force of the collisions, the greater the pressure.

a) Pressure and volume.
If the volume of a fixed mass of gas is decreased the pressure increases.
Explain why this happens in terms of collisions.

In a smaller volume, particles travel a shorter distance before colliding with the container.

They thus collide with the container more often, meaning that pressure increases.

b) Pressure and temperature.
If the temperature of a fixed mass of gas is increased then its pressure will increase.
Explain why this happens in terms of collisions.

particles gain kinetic energy and move faster.

They collide with the container:

harder

and more often

and both factors increase the pressure.

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Melting points: DECREASE

E.g. When salt is added to ice, it melts and its temperature drops.

Salt is used to remove ice from roads - freezing point also decreases.

Boiling points: RISE

E.g. Salt water (103 oC) has a higher boiling point than fresh water (100 oC).

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The effect of adding impurities to substances on their melting and boiling point

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The effect of adding impurities to substances on their melting and boiling point

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How does salt affect the freezing and boiling points of water?

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BROWNIAN MOTION

Robert Brown noticed that pollen grains on water were seen to be moving in a random way when observed under a microscope.  He concluded that invisible tiny particles were moving very fast and were colliding with the pollen grains causing them to move in a haphazard way.

The above observation provides some evidence for the kinetic theory.

Note: smoke in air produces the same effect. In it little ash particles are seen to move as the air molecules collide into them.

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DIFFUSION

Definition:
The spontaneous moving, mixing and spreading of one substance through another substance from a region of high concentration to a region of low concentration until the particles are evenly spread.

Liquids and gases diffuse – solids do not.

When a gas jar containing air (colourless) is placed on top of a gas jar containing a red-brown gas (e.g. nitrogen dioxide or bromine), the red-brown colour spreads up into the air until the gas in both jars looks the same colour.

Gases diffuse faster than liquids. Explain why.

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Diffusion of ammonia gas and hydrogen chloride gas to form ammonium chloride.

HCl is heavier than NH3 molecule and move slower towards NH3.

NH3 is lighter molecule than HCl and moves faster.

Hence the two gases meet each other off centre in the tube to react.

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North Carolina School of Science and Mathematics

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Concentration increases Rate of Reaction 

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Concentration increases Rate of Reaction 

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EVAPORATION

Definition:  The loss of particles through the surface of a liquid into the gaseous phase.

It is the faster moving particles which leave a liquid. Therefore the particles left are moving slower on average and the liquid cools.

A liquid which evaporates readily is called VOLATILE. (e.g. ether)

List 4 factors which increase the rate of evaporation of a liquid like water.

1. ________________________________________________________________
2. ________________________________________________________________
3. ________________________________________________________________
4. ________________________________________________________________

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The pressure of a gas results from particles colliding with the sides of the container.

Therefore the greater the number of collisions and the greater the average force of the collisions, the greater the pressure.

a)     Pressure and volume.

If the volume of a fixed mass of gas is decreased the pressure increases.

Explain why this happens in terms of collisions.

________________________________________________________________

________________________________________________________________

b)     Pressure and temperature.

If the temperature of a fixed mass of gas is increased then its pressure will
increase.

Explain why this happens in terms of collisions.

_______________________________________________________________
_______________________________________________________________

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Pressure in Gases | Matter | Physics | FuseSchool

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Relationship between Pressure and Volume

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Relationship between Pressure and Volume

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The relationship between pressure and volume

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Relationship between Pressure and Temperature

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Relationship between Pressure and Temperature

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The effect of an increase in temperature on pressure and volume of a gas

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Fahrenheit, Celsius and Kelvin explained in ten seconds