Chemistry- Classification of matter

Groups

Atomic radius

Distance from the nucleus to the outermost electron shell of an atom

Decreases across a period

Increases down a group

Ionic radius

The distance from the nucleus to the outermost electron shell of an ion

Decreases across a period

Increases down a group

Parent ions

Cations are smaller than parent ions (due to increased effcetive nuclear energy pulling electron closer)

Anions are larger than parent ions (due to extra repulsion spreading the elctron cloud out further)

Ionisations energy

Increases across a period

Decreases down a group

Electron affinity

Amount of energy released when one mole of electrons is gained by one mole of atoms of an element in the gaeous state to form one mole of gaseous ions.

1st is usually exothermic/ 2nd can be endothermic

Exothermic across a period

Endothermic down a group

Electronegativity

Increases across a period

Decreases down a group

Physical Group 1 properties

Softer as you go down the group

Conduct heat and electricity

Have low melting points and densities

Chemical Group 1 properties

Reactivity increases down a group

Colours and states of halogens at room temp

Colour of halogen solutions in water:

• Fluorine: not typically tested due to its reactivity

• Chlorine: green-blue solution

• Bromine: orange solution

• Iodine: dark brown solution

Reactivity trend in group 17

Decreases down the group

Displacement

Chlorine>Bromine>Iodine

Period 3 oxides

Oxidation states

Absorbed vs. Transmitted colour

The colour that is seen is complementary to the colour that is absorbed