CS5. 3. STATES AND PROPERTIES OF MATTER

Atmosphere (n)

/ˈæt.mə.sfɪər/

(n) The mixture of gases around the earth

The layer of air that surrounds the Earth is called the __________.

Compressed (v)

/kəmˈpres/

(v) to press something into a smaller space

This explains why solids, such as bricks, have a fixed shape and cannot be squashed or __________.

Atmosphere (n)

/ˈæt.mə.sfɪər/

(n) The mixture of gases around the earth

The layer of air that surrounds the Earth is called the __________.

Compressed (v)

/kəmˈpres/

(v) to press something into a smaller space

This explains why solids, such as bricks, have a fixed shape and cannot be squashed or __________.

Invisible (adj)

/ɪnˈvɪz.ə.bəl/

(adj) impossible to see

We don’t always know that gases are there because we can’t see most gases. These gases are __________.

Layer (n)

/ˈleɪ.ər/

(n) The __________ of air that surrounds the Earth is called the atmosphere.

Pollute (v)

/pəˈluːt/

(v) to make an area or substance, usually air, water, or soil, dirty or harmful to people, animals, and plants, especially by adding harmful chemicals

Many things that people use every day can __________ the air. Smoke from cigarettes and cooking, and fumes from spray cans and paints also pollute the air.

Pollution (n)

/pəˈluː.ʃən/

(n) damage caused to water, air, etc. by harmful substances or waste

These substances make the air dirty and harmful to living things.

We say that they cause air __________.

Properties (n)

/ˈprɒp.ə.ti/

(n) A property is also a particular physical or chemical characteristic of a substance

The particle model of matter describes the structure of solids, liquids and gases and explains their __________.

Structure (n)

/ˈstrʌk.tʃər/

(n) an object such as a building, that has been built or arranged in a particular way

The particle model of matter describes the __________ of solids, liquids and gases and explains their properties.

Melt (v)

/melt/

(v) to turn from something solid into something soft or liquid

Water changes state when it is heated or cooled. For example, when we heat ice, it __________ to form liquid water.

Melting point (n)

/ˈmel.tɪŋ ˌpɔɪnt/

(n) the temperature at which a substance melts

This is when it changes from a solid to a liquid. The __________ of ice is 0°C.

Freeze (v)

/friːz/

(v) If you freeze something, you lower its temperature below 0°C, causing it to become cold and often hard, and if something freezes, its temperature goes below 0°C

Water __________ at 0°C. This means that the melting point of ice is the same as the freezing point of water.

Freezing point (n)

/ˈfri·zɪŋ ˌpɔɪnt/

(n) the temperature at which a liquid becomes solid

Water freezes at 0°C. This means that the melting point of ice is the same as the __________ point of water.

Boil (v)

/bɔɪl/

(v) to reach, or cause something to reach, the temperature at which a liquid starts to turn into a gas

If we heat water enough, it will boil. When water __________ it forms bubbles of a gas called steam.

Boiling point (n)

/ˈbɔɪ.lɪŋ ˌpɔɪnt/

(n) The temperature at which a substance boils

This is when it changes from a liquid to a gas.

The __________ of water is 100°C.

Steam (n)

/stiːm/

(n) the hot gas that is produced when water boils

If we heat water enough, it will boil. When water boils it forms

bubbles of a gas called __________.

Contract (v)

/ˈkɒn.trækt/

(v) to make or become shorter or narrower or generally smaller in size

When the substance cools down, its particles move more slowly because they have less energy and move closer together. The cooled substance takes up less space. It gets smaller, or __________.

Expand (v)

/ɪkˈspænd/

(v) to increase something in size, number, or importance

We know from the particle model of matter that when substance gains heat its particles move faster and spread out. This makes the substance take up more space. We say that the substance __________.

Temperature (n)

/ˈtem.prə.tʃər/

(n) the measured amount of heat in a place or in the body

The amount of heat in a substance is called the temperature. We measure __________ with a thermometer. The unit we use is degrees centigrade (°C).

Thermometer (n)

/θəˈmɒm.ɪ.tər/

(n) a device used for measuring temperature, especially of the air or in a person's body

The amount of heat in a substance is called the temperature. We measure temperature with a __________. The unit we use is degrees centigrade (°C).

Evaporate (v)

/ɪˈvæp.ər.eɪt/

(v) to cause a liquid to change to a gas, especially by heating

Water changes into a gas called water vapour. When particles on the surface of a liquid change into a gas, we say the liquid __________.

Evaporation (n)

/ɪˌvæp.əˈreɪ.ʃən/

(n) the process of a liquid changing to a gas, especially by heating

__________ happens because some particles in the liquid gain heat energy. The heated particles start to move faster and move further apart.

Condensation (n)

/ˌkɑn·dənˈseɪ·ʃən, -den-/

(n) the process by which water vapor in the atmosphere (= air surrounding the earth) cools and changes into liquid water.

If the surface is cold enough, the water vapour gas changes to drops of liquid water. The process is called __________. It is the reverse of evaporation.

Reverse (n)

/rɪˈvɜːs/

(n) the opposite of what has been suggested

If the surface is cold enough, the water vapour gas changes to drops of liquid water. The process is called condensation. It is the __________ of evaporation.

Water cycle

/ˈwɔː.tə ˌsaɪ.kəl/

Water keeps going around and around in what we call the __________. In the water cycle, water moves from the land and sea to the air and back again.

Precipitation (n)

/prɪˌsɪp.ɪˈteɪ.ʃən/

(n) water that falls from the clouds towards the ground, especially as rain or snow

The rain and snow that fall from clouds onto the Earth are called __________. Sometimes balls of ice called hail also fall from the clouds.

Dissolve (v)

/dɪˈzɑlv/

(v) to be absorbed or to cause a solid to be absorbed by a liquid, or of a liquid to absorb a solid

The sugar has __________ in the tea. This means that the particles of sugar have spread out into the spaces between the particles of the tea.

Soluble (adj)

/ˈsɒl.jə.bəl/

(adj) able to be dissolved to form a solution

Solids that can dissolve in a liquid are called __________ solids. Being able to dissolve is a property of the solid. Not all solids can dissolve. These solids are insoluble.

Insoluble (adj)

/ɪnˈsɒl.jə.bəl/

(adj) (of a substance) impossible to dissolve

Solids that can dissolve in a liquid are called soluble solids. Being able to dissolve is a property of the solid. Not all solids can dissolve. These solids are __________.

Solution (n)

/səˈluː.ʃən/

(n) a mixture in which one substance is dissolved in another, especially a solid dissolved in a liquid

Mixtures are made of particles of different substances mixed together. Dissolving is a type of mixing because when the solid dissolves it mixes with the liquid. We call the mixture a __________.

Solute (n)

/ˈsɒl.juːt/

(n) a substance that has been dissolved in another substance

The solid in the solution is called the __________, for example sugar.

Solvent (n)

/ˈsɒl.vənt/

(n) a liquid in which another substance can be dissolved

The liquid is called the __________, for example tea.

Universal (adj)

/ˌjuː.nɪˈvɜː.səl/

(adj) Many substances dissolve in water. This is another one of

water’s properties. Water is sometimes called the __________

solvent because so many substances can dissolve in water.

Fertilisers (n)

/ˈfɜː.tɪ.laɪ.zər/

(n) a natural or chemical substance that is spread on the land or given to plants, to make plants grow well

Farmers put chemical __________in the soil to make their crops grow better. These __________ sometimes wash into rivers and pollute the water.

Pesticides (n)

/ˈpes.tɪ.saɪd/

(n) a chemical substance used to kill harmful insects, small animals, wild plants, and other unwanted organisms

Many farmers also spray chemicals on their crops to kill pests like insects. These chemicals are called __________.

Uniform (adj)

/ˈjuː.nɪ.fɔːm/

(adj) The particles of the solute move between the solvent particles when they dissolve. The solute particles spread evenly in the solvent. Because of this you cannot see the solute in a solution after it has dissolved. We say that a solution has a __________ appearance – it is the same throughout.

Reversible (adj)

/rɪˈvɜː.sə.bəl/

(adj) If something is reversible, it can be changed back to what it was before

We can separate the dissolved solute from a solution by evaporation. We call this a __________ process because we can get back the dissolved solute from the solution.