MATTER AND STATES OF MATTER
Anything that is around us is a kind of matter
o natural materials: wood, water, air, sand
o artificial materials: paper, glass, iron
A property is something about an object that you can observe:
o size o smell, taste
o colour o flexible
o shape
Matter has 3 forms states of matter
o Solid: its particles stay close together; they do not change places
o Liquid: takes the shape of their containers; its particles move around each other
o Gas: it can spread out to fill any space because the particles move around freely
PHYSICAL CHANGES
Melting:
o solid turns into liquid
o melting point: the temperature where the matter starts to melt (e.g. water starts to melt at 0°C)
Freezing:
o Liquid turns into solid
o Freezing point: the temperature when the matter is freezing (e.g. water0°C)
Evaporation:
o Liquid turns into gas
o The temperature of evaporating matter is decreasing (e.g. sweating)
Boiling:
o Liquids turns into gas
o When we heat water, its tiny particles start moving faster
o e.g. Boiling point of the water is 100°C
Condensation:
o Gas turns into liquid
o e.g. glasses: cold lenses meet the warmer temperature
Physical changes:
o They are changes in the way the matter looks (size and shape – the material itself doesn’t change)
PROPERTIES OF GASES AND AIR
Air is all around us
o The particles of gases move in all directions
o It’s colourless and odourless
We breath the mixture of different gases: nitrogen, oxygen, carbon-dioxide
Humans: Plants:
o Inhale: oxygen o Need: CO2
o Exhale: CO2 o Make: O2
The hotter air becomes lighter, so it rises
The cold air is heavier, so it sinks
Atmospheric pressure
o The weight of air that presses down on a given surface
o Measure with: barometer
o Measure in: bars
o It is highest at sea level, and gets lower in high mountains
MIXING AND DISSOLVING
Mixture
• You will get a mixture if you mix two or more different components.
• You can mix any kind of materials in any states of matter together
o The elements of the mixture do not change chemically
o e.g. lemonade, cocktails
Solutions
• Solutions are also mixtures of two or more chemicals
o BUT! In this case, the particles are completely dissolved
• Water is a very good solvent – substance which things can be dissolved in
• e.g. tea
Separate mixtures
• In a mixture all substances that are mixed together can also be separated easily
• e.g. cereal + raisins
Separating solutions
• It is a complicated process
• E.g.: salt can be separated from sea water by filling shallow basins with the sea water and letting the
water evaporate off à what remains is salt at the bottom of the basin
CHEMICAL CHANGES - Burning
Difference between physical and chemical changes
o Physical changes: the inner structure of matter does not change
Most of them are reversible
o Chemical changes: at the end of the reaction, one kind of matter will change into another kind
These changes cannot be reversed
A chemical change takes place when something (e.g. heat) causes substance to change into a new substance
(e.g. baking)
Burning
o Burning is a process with a high temperature, flames and light
It needs oxygen
Fire changes the wood into ashes and smoke (gas)
Other chemical changes:
o ‘slow burning’
Rusty nails are caused by oxygen in air that mixes with the material that makes up the nails
o Change in colour
On silver subjects: oxygen in air causes greyish-black covering called tarnish
GROUND AND SOIL
The soil is the top fertile layer of the ground.
o A talaj a földfelszín felső, termékeny rétege.
It contains small pieces of broken-up rocks and minerals.
Another important element in soil is humus.
o Humus is a dark-coloured organic material which is formed from tiny particles of dead animals and
plants.
It gives the soil its colour and fertility
Layers of soil: top soil with humus – subsoil – decaying rocks – bedrock (DRAWING!)
Natural forces (rain, ice, temperature, wind) make rocks break up or weather into smaller pieces
Soil particles are varied
o Sandy soil: has bigger particles, contains more water and air than clay
o Loam: is a mixture of sand, clay and humus
