Group 0, 1 and 7 and Gases in the Atmosphere 2.1-2.14

Inert/ unreactive because they have a full outer shell of electrons, so no tendency to lose and gain or share electrons

• Soft and can be easily cut • Less dense than water • Shiny when freshly cut, but rapidly tarnish on exposure to air

All react vigorously

metal + water –> metal hydroxide + hydrogen

Metal oxides Type of oxide depends on the metal - High reactivity metals tarnish faster as metal oxide forms faster

More reactive down the group Can be seen with the rate of reaction with water and oxygen - faster = higher reactivity Can use the trend to predict how other group 1 metals will react e.g. caesium more vigorous in water than potassium

Atoms lose electrons more easily down the group • All have 1 electron in their outer shell • As you go down the group the outermost electron is in a shell that’s further from the nucleus –> attraction between electron and nucleus is less • As you go down the atoms get bigger, the outer electron is more easily lost, and the metals are more reactive

-1

Down the group (as the atomic number increases) darker and higher melting and boiling points

As the molecular mass increases the intermolecular forces get stronger, hence more energy is required to overcome them

Decrease as you go down the group

More reactive halogen will displace less reactive ones Displacement –> transfer of electrons (oxidation or reduction)

Gain 1 electron –> easier it is to gain this electron the more reactive the halogen will be • Atoms get bigger down the group • Outer shell is further from the nucleus • There is a weaker attraction between the nucleus and the incoming electron so less tendency of gaining an electron to fill the outer shell

• Put 3 rows of chloride, bromide and iodide (colourless halide solutions) into a dimple tile • Now add 2-3 drops of chlorine (colourless) solution to the bromide and iodide Add 2-3 drops of bromine (pale yellow/orange) solution to the chloride and iodide Add 2-3 drops of iodine (orange) solution to chloride and bromide • Record observations

Only ones that react potassium bromide + chlorine = pale yellow potassium iodide + chlorine = yellow/orange potassium iodide + bromine = orange

Redox reactions

The thing that gets oxidised

The thing which gets reduced

78% nitrogen 21% oxygen 1% (0.96%) argon 0.04 Carbon dioxide

1) Push a piece of wet iron wool into a test tube 2) Invert the test tube into a beaker that is half full of water 3) Measure the height of the air in the the test tube and leave the test tube at an angle for at least one week 4) Measure the height of the test tube

1) Place the phosphorus in a tube and attach a glass syringe at ether end, one syringe filled with air and the other empty 2) Heat the phosphorus and use the syringes to pass the air over it - the phosphorus will react with oxygen in the air to make phosphorus oxide 3) As it reacts, the amount of air in the syringes will decrease 4) Measure the starting and final volume of air using the scale on one of the syringes 5) Calculate the percentage of oxygen in the air

Start volume - final volume/start volume x 100

2Mg (s) + O2 (g) –>2MgO (s) • Bright white flame • White solid (powder) forms called magnesium oxide

2H2 (g) + O2 (g) –> 2H2O (l) • Pale blue flame • Squeaky pop