C4 chemical patterns revision notes

notes from the revision guide and from class

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  • Created on: 27-06-10 19:35
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C4 ­ Chemical Patterns
The nucleus contains positively charged protons and an equal
amount of neutrons which have no charge. The number of
protons decides what element it is. The nucleus provides the
weight of the atom. Negatively charged electrons orbit the
nucleus is shells and give the atom its volume if these are
added or removed the atom gains a charge and becomes an ion.
The atoms structure gives the elements its properties.
Particl Relative Relative
e mass charge
proton 1 +1
neutron 1 0
electro 0.0005 -1
Electrons form themselves in shells, the lowest energy levels fill up first but can only hold
set amounts.
1st ­ 2 2nd ­ 8 3rd ­ 8 4th ­ 18
The amount of electrons is always equal to the amount of proton so the electron structure
of an atom isn't hard to work out. Oxygen is 2,6.
Isotopes are atoms of the same element but with different masses due to different
amounts of neutrons.
Balancing equations
Before working with an equation it must be balanced, atoms don't appear and disappear.
Firstly check that there is the same number of each atom in the reactants as the products, if
not work on each atom at a time multiplying the molecule until they are balanced. Also
equations are finished with state symbols Aq ­ aqueous, L- liquid, S- solid, G ­ gas.
Line spectrums
Some elements emit distinctive colours when heated; this is how fireworks get their
Element Symbol Flame colour
lithium Li red
sodium Na yellow
potassium K lilac

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These can be used to identify a metal in a compound.
We see colours because when heated the electrons release energy as light these can be
recorded in a spectrum. Different element emit different wave lengths, therefore it can be
used to identify elements. This technique is called spectroscopy.
The periodic table
Laid out increasing proton
Metals and non metals
Element with similar qualities form
Groups have the same number of
electrons in their outer shell
Each shell fills a row e.…read more

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Fluorine, chlorine, bromine, iodine and astatine all have seven electrons in their outer shell
making them very reactive; because of having 7 electrons they make diatomic molecules
(pairs of atoms) to fill their outer shell. They become less reactive as you go down as the
outer shell is further away from the nucleus making the attraction weaker. They have
relatively low M.P and B.P but it increases as you go down.…read more

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Atoms lose or gain an electron to have full shell and form charged particles, ions. It is
most common in the group 1 and group 7 elements.
The charges in an ionic compound should be neutral, ions can have different changes
gaining or losing more than one electron.
By knowing that there is no overall charge the charge of the ions can be worked out.…read more


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