C4 - Revision Summary

Página 1

The nucleus of an atoms contains protons & neutrons.

The relative atomic mass of a neutron is 1 and the charge is 0.

(s)-solid (l)-liquid (g)-gas & (aq) aqueous (dissolved in water).

a) 2Na + Cl2 ---> 2NaCl b) 2K + 2 h2O ---> 2KOH + H2

When heated, the electrons in an atom

are excited and release energy as light. The line spectrum obtained is specific

to that element. By comparing the spectrum to known spectra, the element can be

identified.

Elements give distinctive spectrum because the spectrum is dependent on the elements electronic configuration. As

each element has a unique electronic configuration, it has a unique line

spectrum.

Line spectrum can be used to identify what element a sample is or to show that a

sample contains a newly discovered element ( this is how Caesium, Rubidium and Helium were discovered).

Dobereiner

organised elements into groups of three called traids. These groups were based on chemical

properties.

Newlands octaves were criticised because he mixed metals with non metals and didn't leave any gaps and the pattern broke down on the third row.

Mendeleev had to left gaps in order

to keep elements with similar properties in the same vertical group. He was

prepared to leave some very large gaps in the first few rows in order to

maintain his pattern.

An elements proton number determines it's position in the periodic table as it is arranged by increasing proton number.

Elements in the same group have very

similar chemical properties. This is because elements in the same group have

the same amount of electrons in their outer shell.

The rows in the periodic table are known as periods

One atom of oxygen contains 8 protons.

The first shell of any atom can hold 2 electrons.

The electron configurtaion of carbon is 2,6

Atoms in group one have 1 electron in

their outer shell. They can have a full outer shell by losing 1 electron. By losing

an electron, group one elements become positive ions.Atoms in group seven have 7 electrons

in their outer shell. They can have a full outer shell by gaining 1

electron By

gaining an electron, group 7 elements become negative ions.

Ionic bonding is a transfer of electrons between elements. This forms negative and

positive ions which have full outer shells. These positive and negative

elements are attracted to each other.

Ionic compounds form giant lattice structures.

In a compound there must be the same

amount of positives and negatives for it to be neutral over all. There are two bromide ions, so if each

has a charge of -1, this gives a total charge of -2. The single magnesium ion must

therefore have an opposite charge of +2.

a) iron (II) oxide FeO b) Iron (III) chloride FeCl2 c) Calcium oxide CaO d) Sodium carbonate Na2CO3

Alkali metals are group 1

As you go down group 1 the alkali metals become more reactive

The alkali metals react with water to

form hydrogen and an alkali. These reactions become more reactive as we go down

the group.

2Li(s) + Cl2(g) ---> 2LiCl(s)

Atoms that tend to go round in pairs

are referred to as diatomic.

As you go down group 7 the halogens become less reactive.

Chlorine at room temperature is a dense green gas.

3 experiments that could be used to determine the relative reactivity of the halogens are reactions with alkali metals & reactions with iron and displacement reactions

a) The hazard symbol means corrosive which means that it can attack and destroy living tissue b) An example of a substance is concentrated sulfuric acid

Gloves should be worn when using

liquid bromine as it is corrosive and most of the halogens have poisonous

vapours and so must be used in a fume cupboard. If the fumes are inhaled or get

into eyes they can be severely irritating to the respiratory system.