Group I metals - alkali metals

Question 1

Touch

Answer 1

malleable and soft
1. Weaker electrostatic attractive forces between the nucleus and ‘sea’ of mobile valence electrons
2. weaker metallic bond
3. little energy is needed to separate the atoms.

Question 2

Appearance

Answer 2

Dull surface due to layer of oxide but shiny underneath

Question 3

Electrical conductivity

Answer 3

Good conductor of heat and electricity
- ‘sea’ of mobile valence electrons

Question 4

Melting and boiling point

Answer 4

Relatively low melting and boiling point compared to other metals

Question 5

Down the group, the melting point and the boiling point…

Answer 5

decreases
1. atoms increase in size due to an increase in the number of electron shells
2. attraction between the nucleus and ‘sea’ of mobile valence electrons decreases
3. weaker metallic bond
4. lesser amount of energy is needed to separate the atoms

Question 6

Down the group, density…

Answer 6

increases

Question 7

Reactivity

Answer 7

Very reactive
1. each has only one valence electron which is easily lost
2. to give an ion with a charge of +1 resulting in a noble gas configuration

Question 8

React with
1. air or oxygen
2. Reactive non-metals (halogens)

Answer 8

1. catching fire and burning with flame colors
2. react explosively

Question 9

React with water and the observations

Answer 9

Reactivity increases down the group
observations:
1. darts rapidly on the surface of water
2. mass of metals decreases as it dissolves in water to form an alkaline solution and hydrogen gas
–> hydrogen test & it catches fire
3. Bubbling
4. a lot of heat is given off

Question 10

Down the group the reactivity…

Answer 10

Increases
1 atom becomes larger down the group
2. Valence electrons are further away and less attracted to the nucleus
3. the electrostatic attractive forces between the nucleus and the valence electrons decrease.
4. therefore, it is easier to lost electrons to form positive ions.