Alkali Metals

Describe a trend in the melting and boiling points in group 1

The boiling and melting points get lower as you go down the group

Describe a trend in the densities of group 1

The density increases as you go down except for potassium

What is the density of water?

1 g/cm3

Why does Li, Na and K float on water

Because they are less dense than water

Describe the trend in softness in group 1

They get softer as you go down the group

Name some common properties of group 1

Shiny and silver when freshly cut, tarnish in air quickly

Are group one metals reactive?

Yes

Describe the trend in reactivity in group 1

The reactivity increases down the group

What do they form when reacting with water?

Hydroxide and hydrogen gas

What is the chemical formula of the product water and group 1 metals form?

2M + 2H2O → 2MOH + H2

How does the speed change of reacting in group 1?

Get faster down the group because it gets more reactive down the group

What happens when sodium reacts with water and give reasons

It floats (less dense than water), melts into a ball (melting point is low, reaction is exothermic), fizzing (hydrogen gas produced), moves around the surface, sodium gets smaller until gone, ends with a yellow flame

How is lithium’s reaction with water similar to sodium?

Similarities: float on water, fizz, exothermic

Differences: slower (higher melting pt), does not melt significantly

How is potassium’s reaction with water similar and different to sodium’s?

Similarities: melt, exothermic, float on water and move around

Differences: faster (cannot see the ball), more violent, results in a lilac flame, can cause small explosion

How is rubidium and caesium’s reaction with water different to sodium’s?

Similarities: exothermic, melt

Differences: more violent, faster, explosive, sinks in water

What do they react with oxygen to form?

Oxide

What is the chemical formula for what oxygen and group one metals form?

M2O

What do they react with halogens to form?

Alkali metal halides

What is the chemical formula for the formed compound between halogen and alkali metals

MX

When a group one metal becomes an ion, what its its charge?

M+

What can be done to prevent a reaction with oxygen and water vapour

Store in oil

How is rubidium and caesium stored differently and why?

Stored in a sealed glass tube because they are so reactive