Group chemistry

Lithium, sodium and potassium are all examples of

Group 1 alkali metals

What group are the alkali metals in

1

What are the alkali metals at room temperature

Shiny metallic solids

alkali metal melting and boiling points

Low for metals, decrease down the group

Densities of alkali metals

Low for metals, increase down the group

Do alkali metals melting points increase or decrease down the group

decrease

Why do alkali metals melting points melting/boiling points decrease down the group

Weaker metallic bonds as distance of outer shell from nucleus becomes greater

Hardness of alkali metals

Soft, become softer down the group

conductivity of alkali metals (heat and electricity)

Good conductors

Why do group 1 metals get denser as u descend the group

Increasing mass of individual ion cores

Why do alkali metals become softer as the group is descended

weaker metallic bonds as distance of outer shell electron increases

Reactivity of alkali metals

Very reactive, increases down the group due to increased atomic radius despite increase in nuclear charge

Why are group 1 elements usually stored in oil

Prevent reaction w o2/water in air

Reaction of lithium, sodium and potassium with water observations

Float, move on surface, fizz

What is produced when alkali metals react w water

Metal hydroxide and hydrogen

Equation for reaction of alkali metals w water

2[M] (s) + 2H2o → 2 [M]OH (aq) + h2 (g)

Potassium reaction with water

Hydrogen spontaneously ignites, burns with lilac flame due to K+ ions

Reaction of alkali metals with halogens

Vigorous, produces metal halide salts

Is trend of increasing reactivity for group 1 as u go down the group consistent for all reactions?

Yes

Group 17 is known as

Halogens

Fluorine, chlorine, bromine and iodine are all examples of

Group 17 halogens

Astatine is an example of

Halogen

Rubidium and caesium are both

Alkali metals

Melting boiling points of halogens

Low, increase down the group

Conductivity of halogens

Poor

Which group exists as diatomic molecules

Halogens

Fluorine at rtp

Pale yellow gas

Chlorine description rtp

Yellow green gas

Bromine description rtp

Red brown volatile Iiquid (orange vapour)

Iodine description rtp

Grey shiny solid (purple vapour)

Why do melting boiling points of halogens increase as group is descended

Bigger molecules = stronger intermolecular forces

What do halogens need for a full outer shell

Gain one electron

Reactivity of halogens

Decrease down the group

Why do halogens get less reactive as they get bigger

Larger distance from nucleus to outer shell - harder to gain an electron

Reaction of halogen with alkali metals equation

2 [M] (s) + [H]2 → 2[H][M] (s)

What can chlorine displace in solution

Bromine and iodine

What can bromine displace in solution

Iodine

Can iodine displace bromine or chlorine

No

Why can some halogens displace others in solution of its salt

more reactive - can oxidise (take electron from) other ion

What happens when a halogen is displaced in solution

The solution turns the colour of the displaced halogen

Colour of chlorine water

Colourless

Colour of bromine water

Orange

Colour of iodine solution

Brown

Colour of potassium halide salt in solution

Colourless

Group 18 is known as

Noble gases

Helium, neon and argon are all

Group 18 noble gases

Krypton and xenon are both

Noble gases

Noble gas description at rtp

Colourless gas

Melting and boiling points of noble gases

Very low, increase down the group

Why do melting boiling points of noble gases increase down the group

Larger atoms - stronger ‘intermolecular’ forces between atoms

Why does density of noble gases increase increase down the group

Increased mass of atoms

Trend in density of noble gases

Increase down the group

Do noble gases exist as diatomic molecules

No

Why are noble gases so unreactive/inert

Full outer shell

Which group of elements is used to provide an inert atmosphere

18 - noble gases