(a) group 1 (alkali metals) - lithium, sodium and potassium

how does lithium react with water (2.1 / 2.2)

fizzing (produces hydrogen), floats and whizzes around, disappears

produces lithium hydroxide and hydrogen

melting point of lithium: 181°C

density of lithium: 0.53 g/cm³

how does sodium react with water (2.1 / 2.2)

rapid fizzing (produces hydrogen), floats and whizzes around, melts into a ball, disappears

produces sodium hydroxide and hydrogen

melting point of sodium: 98°C

density of sodium: 0.97 g/cm³

how does potassium react with water (2.1 / 2.2)

violent fizzing (produces hydrogen), floats and whizzes around, bursts into a lilac flame, disappears

produces potassium hydroxide and hydrogen

melting point of potassium: 63°C

density of potassium: 0.86 g/cm³

how does lithium react with air (2.2)

it doesn’t

how does sodium react with air (2.2)

reacts with the water vapour in the air

how does potassium react with air (2.2)

reacts with oxygen

group 1 trends (2.3 / 2.4C)

you can roughly predict the melting point and density of rubidium, caesium and francium if you plot the melting point and density of lithium, sodium and potassium

you can also predict how they will react with water and what they will produce (it will get increasingly violent because as you go down the group, the outer electron lost from the metal is further from the nucleus → the electron is less attracted by the nucleus and is therefore more easily lost) → they will all fizz, whizz around and burst into flame.

rubidium will produce rubidium hydroxide and hydrogen, caesium will produce caesium hydroxide and hydrogen, francium will produce francium hydroxide and hydrogen