AQA Core Chemistry 1a - Products from Rocks.
Atoms and Elements.
1) The nucleus is in the middle of the atom.
2) It contains protons and neutrons.
3) Almost the whole mass of an atom is concentrated in the nucleus.
4) But size-wise it is tiny compared to the rest of the atom.
1) Electrons move around the nucleus in shells.
2) They're tiny, but cover a lot of space.
3) Electrons shells explain the whole of chemistry.
Recent evidence shows that atoms may be made of subatomic particles, some of them are just to difficult to "see". This suggests that an atom being made of just protons, neutrons and electrons is probably not quite right, but it still helps explain a lot of things.
Elements Consist of One Type of Atom Only.
1) Atoms have a different number of protons, neutrons and electrons. It is the number of protons in a nucleus that decides what type of atom it is though.
2) For example an atom with one proton in it's nucleus is hydrogen, but an atom with two protons is helium.
3) If a substance only contains one type of atom then it is called an element. Quite a lot of everyday substances are elements like copper, aluminium, iron, oxygen, nitrogen...
The Periodic Table.
Atoms Can Be Represented by Symbols.
Atoms of each element can be represented by a one or two letter symbols, it is a type of shorthand that saves you the bother of having to write full name of the the element.
For example: C = Carbon Li = Lithium Mg = Magnesium
Be careful though, some symbols come from the Latin names.
For example: Na = Sodium Fe = Iron Pb = Lead
The Periodic Table Puts Elements with Similar Properties Together.
1) The periodic table is laid out so that elements with similar properties form columns.
2) These vertical columns are called groups and Roman numerals are often used for them.
3) If you know the properties of one element, you can predict properties of other elements in that group.
4) For example The Group I elements are Li, Na, K, Rb, Cs and Fr. They're all metals and they react the same way. E.g. they all react with water to form an alkaline solution and hydrogen gas.
5) You can also make predictions about reactivity. E.g. in Group I, elements react more vigorously as you go down the group. In Group…