1. Building Blocks

2. Particle and Kinetic Theory
Substances are made up of particles. The state of the substance depends on the arrangement of the particles.
The Three States of Matter
Solid
Particles held tightly
Very close together
Regular arrangement
Vibrate
Can’t move from place to place
Liquid
Particles held weakly
Very close together
Random arrangement
Vibrate
Constantly move past each other
Gas
No attraction between particles
Far apart
Random arrangement
Vibrate
Move quickly in all directions

3. Atoms and Elements
Elements consist of only one type of particle. We call these particles atoms.
They cannot be split into simpler, smaller particles by chemical methods.
There are about 109 elements known at the moment (2004). Don’t worry, you don’t have to learn them all!
The elements each have a name and a symbol.
By the end of year 9, you must know the first twenty elements off by heart, so it is a good idea to start learning them now!

4. The First Twenty Elements
Atomic
Number
Symbol
Name 1 H
hydrogen 11 Na
sodium 2 He
helium 12 Mg
magnesium 3 Li
lithium 13 Al
aluminium 4 Be
beryllium 14 Si
silicon 5 B
boron 15 P
phosphorus 6 C
carbon 16 S
sulphur 7 N
nitrogen 17 Cl
chlorine 8 O
oxygen 18 Ar
argon 9 F
fluorine 19 K
potassium 10 Ne
neon 20 Ca
calcium

5. Arranging the Elements
As you know, the elements are arranged in the Periodic Table.
The elements were first arranged in this way by Dmitri Mendeleev, a professor at St. Petersburg University, in His arrangement was based on atomic mass.
When Mendeleev was setting out the table, only 63 elements had been discovered. His big idea was to leave gaps for yet to be discovered elements. He was able to predict the properties of some of these elements, including silicon and boron. When his predictions were shown to be accurate his table became accepted, and it is the basis of the one we use today.
‘Maybe one day we’ll understand why Dmitri always lays out his blocks this way!’

6. Non- Metals Metals Arranging the Elements : Metals and Non-Metals
Most of the elements are metals. The non-metals are found to the top right of the periodic table.
The metals and non-metals are separated by a sort of ‘stair case’.
Non-
Metals
Metals

7. Arranging the Elements : Groups and Periods
The columns of the periodic table are called Groups. Elements in a group have similar properties.
Group 1
Group 2
Group 3
Group 4
Group 5
Group 6
Group 7
Group
Group 2 : Alkaline earth metals
Group 1 : Alkali metals
Group 0 : Noble gases
Group 7 : Halogens
Transition metals
The horizontal rows are called Periods.

8. X Properties of Metals Metals have the following properties :
They conduct electrical energy well
They conduct thermal energy well
They are shiny
They are malleable (can be hammered into shape)
They are ductile (can be drawn out into wires)
They are sonorous (make a ringing sound when hit)
All except mercury are solids at room temperature X
Only a few metals are magnetic.
Magnetism is not a property of most metals!

9. Properties of Non-Metals
Non-metals have the following properties :
They are poor conductors of electrical energy
They are poor conductors of thermal energy
Many of them are gases
They are brittle if they are solid
Both a diamond and a pencil ‘lead’ are made of the same element – carbon.

10. Elements, Molecules and Compounds
Some elements, such as the noble gases, exist as individual atoms.
Often, elements consist of two or more atoms joined together. We call these molecules.
If more than one type of atom is in a molecule, we call it a compound.

11. Mixtures
This is a mixture of elements made up of atoms, elements made up of molecules, and compounds.
In a mixture, the particles are not joined together.
Atom, molecule or compound?
(click for answer)
atom
Atom, molecule or compound?
(click for answer)
molecule
Atom, molecule or compound?
(click for answer)
compound

12. Naming Compounds
If we heat copper in air, it reacts with the oxygen to make a new compound. We call this compound copper oxide.
We can write a word equation for this :
copper + oxygen  copper oxide
Most metals will react with oxygen to form an oxide. For example :
magnesium + oxygen  (click for answer)
magnesium + oxygen  magnesium oxide
When metals react with oxygen we often say they are corroding.
Iron is a very common metal (steel is mostly made of iron), and it reacts with oxygen to make the compound iron oxide. This is such a common reaction that we give the compound iron oxide a common name – rust!
Iron is the only metal that rusts. The correct term to use for other metals is that they corrode.

13. More Oxygen Compounds
Oxygen also reacts with some non-metals to form compounds.
When carbon burns, the following reaction happens :
carbon + oxygen  carbon dioxide
C + O2  CO2
A molecule of carbon dioxide – one atom of carbon and two atoms of oxygen
And of course, oxygen reacts with hydrogen to form a very common compound!
hydrogen + oxygen  water
2H2 + O2  2H2O
A molecule of water – one atom of oxygen and two atoms of hydrogen

14. More Compounds
Naming compounds is quite straightforward when you get used to it. When metals react with chlorine, they form chlorides.
sodium + chlorine  sodium chloride
Salt (sodium chloride) crystals are made up of millions of sodium and chlorine atoms.
lithium + chlorine  lithium chloride
lithium + chlorine  (click for answer)
With sulphur, sulphides are formed.
iron + sulphur  iron sulphide
magnesium + sulphur  (click for answer)
magnesium + sulphur  magnesium sulphide

15. Element or Compound? methane, CH4 sulphur, S8 compound element
(Click for answer)
(Click for answer)
hydrogen peroxide, H2O2
sulphuric acid, H2SO4
compound
compound
(Click for answer)
(Click for answer)
oxygen (ozone), O3
carbon (buckyball), C60
element
element
(Click for answer)
(Click for answer)

16. Testing for Gases
In some chemical reactions, gases are given off. There are several simple tests we can do to find out which element or compound a gas is. Here are two of them.
Carbon dioxide
Bubble the gas through lime water.
If the lime water turns milky, the gas is CO2.
Oxygen
Hold a glowing splint in the gas.
If the splint relights, the gas is O2.