Matter – States of Matter, Properties and Changes

Matter

Matter takes up space and has massMatter is made of atoms, usually

chemically bonded into moleculesExists in different states

States of Matter

There are 4 states of matter: solid, liquid, gas, and plasma

State of a sample of matter depends on the kinetic energy of the molecules or atoms in the sample

Kinetic energy is the energy of moving things

Kinetic Energy

Kinetic energy is the energy of moving things

Kinetic energy moves from areas of higher energy to areas of lower energy

High energy low energy

Kinetic energy is measured in Joules (J)

Solids

Solids have a definite shape and a definite volume

The atoms and molecules that make a solid, vibrate in place but do not move around

Kinetic Theory of Matter, Solids

Particles in solid matter are held close together by forces between them

Particles vibrate but don’t have enough energy to move out of position

Liquids

Liquids have a fixed volume, but take the shape of the container in which they are found

The atoms and molecules that make a liquid can flow around each other

Kinetic Theory of Matter, LiquidsParticles in liquid matter are held

close together by forces between them

Particles are close enough so that liquid matter has a definite volume

Particles have enough energy to move over and around each other

Gases

Gases have neither a definite shape nor volume

They take the shape of their container

Kinetic Theory of Matter, GasesParticles of a gas have enough

energy to separate completely from one another

Particles of a gas are not close together so they can be squeezed into a smaller space

Particles have enough energy to move in all directions until they have spread evenly throughout their container

Plasma

Plasma is a gaslike mixture of positively and negatively charged particles

They have so much energy that they collide violently and break apart into charged particles

Found in lightning bolts, neon signs, Northern lights, and stars

Plasma, cont.

It is made of electrons and positive ions that have been knocked apart by collisions at very high temperatures or in situations where the matter has absorbed energy

Least common state of matter on Earth but is the most common state of matter in the universe, because stars are made of matter in the plasma state

Thermal Expansion

Almost all matter expands when it gets hotter and contracts when it cools

When matter is heated the particles move faster, vibrate against each other with more force

Particles spread apart slightly in all directions and the matter expands

Thermal Expansion, cont. This effect happens in solids, liquids,

and gasesExamples are the liquid in a

thermometer and expansion joints in roads and buildings

Changes of State

When matter gains or loses energy, it can change from one state to another

Different states of matter correspond to different amounts of energy, these amounts are specific to particular kinds of matter

Temperature can be used to measure the amounts of energy present in the matter

Change of state terms Boiling: liquid changes to a gas Freezing: liquid changes to a solid Condensing: gas changes to a liquid Melting: solid changes to a liquid Evaporating: liquid changes to a gas (but a

temperatures lower than the boiling point) Subliming: solid changes into a gas

without becoming liquid (opposite of sublimation is deposition)

Change of state temperaturesBoiling point: temperature at which a

liquid becomes a gas, this temperature is an identifiable characteristic for different substances

Melting point: temperature at which a solid becomes a liquid

Substances condense or boil at their boiling point, depending on whether energy is being added or taken away

Substances melt or freeze at their melting point, depending on whether energy is being added or taken away

Phase changes

Transitions between solid, liquid, and gaseous phases typically involve large amounts of energy compared to the energy needed to change the temperature of a solid or liquid or gas.

It takes lots of energy to change states (temperature stays constant until state is completely changed).

If heat were added at a constant rate to a mass of ice to take it through its phase changes from solid to liquid water and then to steam, the energies required to accomplish the phase changes would lead to plateaus in the temperature vs time graph.

Boiling point elevation

http://group.chem.iastate.edu/Greenbowe/sections/projectfolder/flashfiles/propOfSoln/colligative.html interactive boiling point and freezing point changes

Adding solute to water increases its boiling point, the solute interacts with the water and energy must be added to overcome the interactions so that the water can then change from a liquid to a gas

Freezing point depressionhttp://group.chem.iastate.edu/Green

bowe/sections/projectfolder/flashfiles/propOfSoln/colligative.html interactive boiling point and freezing point changes

Adding solute to water decreases its freezing point, the solute interacts with the water and energy must be removed to overcome the interactions so that the water can then change from a liquid to a solid

Thermal Energy

Thermal energy is the total energy of the particles in a material

Thermal energy includes the kinetic energy of the particles (their motion or vibration)

Thermal energy also includes the potential energy of the particles (energy due to forces acting within or between the particles)

Heat

Heat is the name given to thermal energy that moves or is transferred

In many things that you read, heat and thermal energy are used interchangeably

Movement of Heat

Heat moves from areas of greater heat (more thermal energy) to areas of lesser heat (less thermal energy)

http://www.iun.edu/~cpanhd/C101webnotes/matter-and-energy/specificheat.html

Temperature

Temperature is the measure of the average kinetic energy of the particles that make up a sample of matter.

As the particles move faster, the temperature rises

As the particles slow down, the temperature falls

Law of Conservation of EnergyLaw of Conservation of Energy –

Energy is neither created nor destroyed. It can change forms.

Heat transfer follows the Law of Conservation of Energy

Energy transfers from areas of high energy to areas of low energy but can neither be created nor destroyed

Thermometers

Liquid inside the thermometer is made of molecules

As kinetic energy of molecules increases, liquid molecules move faster and liquid expands

Liquid rises in the tube inside the thermometer

Thermometers

Rising kinetic energy = rising liquid = rising temperature on thermometer scale

Heating and cooling a thermometer: http://www.middleschoolchemistry.com/multimedia/chapter1/lesson3

Temperature scales - FahrenheitFirst scale developed

Water melts/freezes at 32°F and boils at 212°F

Salt water melts/freezes at 0°F, body temperature was 96°F and degrees were divided into 12s and then into 8s between these two points

Temperature scales - CelsiusCelsius scale based on 100 degrees

between freezing and melting of water

Water melts/freezes at 0°C and boils at 100°C

Temperature scales - Kelvin Important scale used in most of

science

Based on a single point (absolute zero) which is given a value of 0 degrees.

From there, the scale increases by degrees that are the same size as Celsius degrees.

Temperature scales - Kelvin It is a scale that is based on energy

content, rather than on arbitrary temperature values like the other two scales (based on water).

Water freezes at the value 273.15 K and boils at 373.15 Kelvin.

Absolute Zero

0 on the Kelvin scale

Point at which all particle motion stops

Matter has no thermal energy at absolute zero

Law of Conservation of EnergyLaw of Conservation of Energy –

Energy is neither created nor destroyed. It can change forms.

Heat transfer follows the Law of Conservation of Energy

Energy transfers from areas of high energy to areas of low energy but can neither be created nor destroyed

Specific Heat Capacity

Physical property of matterRelates to a substance’s ability to

absorb heatAlso called specific heat

Specific Heat Capacity

Specific heat capacity of a substance is the amount of energy (Joules) required to raise the temperature of 1 gram of the substance by 1 °C

Specific heat capacity =

Objects with low specific heat capacities heat up more quickly than objects with high specific heat capacities.

It takes less energy to raise their temperatures

They also transfer their heat more quickly so they cool down faster

Water has a fairly high specific heat capacity, 4.184 J/g °C

This means it takes a lot of energy to raise the temperature of water 1 °C compared to the amount of energy it takes to heat something with a lower specific heat capacity

Example: Iron (0.45 J/g °C) needs much less energy to change its temperature

Heat conductors and insulatorsObjects with low specific heat

capacities are better conductors of heat

Objects with high specific heat capacities are better insulators because they don’t heat up as quickly

Calorimeter

An insulated container that prevents a chemical reaction from gaining heat from its surroundings or losing heat to its surroundings

Using a calorimeter to calculate specific heat capacityCalorimeter experiments to calculate

specific heat capacities of objects use the Law of Conservation of Energy and the known specific heat capacity of water

When a heated object is placed in a cup of cold water, the heat will move from the object to the water

When the temperature stops changing, the temperature of the object and water are now the same

Using a calorimeter to calculate specific heat capacityWhen the temperature stops

changing, the temperature of the object and water are now the same

Energy transferred to the water is equal to the energy transferred from the object

Calculations:Known:

Specific heat capacity of water = 4.184 J/g °C

Energy transferred to water = mass of water (g) x Temp change (°C) x

4.184 J/g °C

Specific heat capacity of object =

Links for extra activities in Investigation 1p. 22 heating and cooling gas in a

bottlehttp://www.middleschoolchemistry.co

m/multimedia/chapter1/lesson5

p. 24 heating and cooling a metal ball

http://www.middleschoolchemistry.com/multimedia/chapter1/lesson4