C4 - Group 1 and 7

GROUP 1 AND 7

Group 1 metals all have one electron in their  outer shell

This makes them VERY REACTIVE (the outer electron is more easily lost because its furthest from the nucleus so its more likely to react) and gives them all similiar properties (when they react they form similiar compounds)

The alkali metals are SHINY when freshly cut, but when they react with Oxygen in moist air they TARNISH

REACTIVITY INCREASES as you go down the group 1 metals

When lithium, sodium or potassium are put into water, they react very vigorously, (move around the water fizzing furiously)

They produce HYDROGEN . A hydroxide of the metal therefore forms (Sodium Hydroxide NaOH) 

Pottassium for example gets so reactive it becomes hot and ignites it. If it hasn't been ignited by the reaction, a lighted splint will indicate hyrogen by producing the "squeaky pop sound" as it ignites.   The reaction makes an alkaline soulution which is why they are known as Alkali Metals

The experiment shows relative reactivities (more violent the rection, the more reactive it is)

Alkali metals also react vigorously with CHLORINE

The reaction produces colourless crystalline salts 

Eg. Lithium Chloride (LiCl) , sodium Chloride (NaCl) and potassium Chloride (KCl)

Group 7 elements all have 7 electrons in their outer shell

This makes them VERY REACTIVE and gives them similiar properties

They form DIATOMIC MOLECULES = pair of atoms

As you go down the group , the elements beome LESS REACTIVE (the outer electrons are further away from the nucleus and they aren't as strongly attracted)

Melting point and Boling point however increases as you go down the group

The Halogens are all NON-METALS

They go from gases to solids down the group which shows the trends in melting and boiling points.

Fluorine is a very  reactive, poisonus yellow gas at room temperature

Chlorine is a fairly reactive, poisonous dense green gas at room temperature

Bromine is a dense, poisonous orange volatile liquid at room temperature and forms an orange gas

Iodine is either a dark grey crystalline solid or a purple vapour at room temperature 

Reactions with Alkali Metals

• The halogens react with Group 1 Alkali Metals to form METAL HALIDES
• Eg. Sodium Chloride (NaCl) Potassium Bromide (KBr) and Lithium Iodide (LiL)
• Reactions become less vigorous as you go down the group
• 2Na (s)   +  Cl2 (g)                         2NaCl (s)

Reactions with Iron

• They react with irons to form COLOURED SOLIDS
• Reactions become less vigorous as you go down the group
• 2Fe(s) +   3Cl(g)                         2FeCl (s)

Displacement Reactions

• A dispalcement reaction is where a more reactive element 'pushes out' (displaces) a less reactive element from a compound
• Chlorine is more reactive than iodine so chlorine reacts with Potassium iodine solution to form Potassium Cloride