Group 1 - Alkali Metals

Question 1

Properties of Group 1 metals : hardness

Answer 1

Relatively soft

Question 2

Properties of Group 1 metals : relative melting point, compared to most other metals

Answer 2

Low melting point

Question 3

Potassium + water -> potassium hydroxide + hydrogen

2K₍s₎ + 2H₂O₍ L₎ -> 2KOH₍ aq₎ + H₂₍ g₎

Answer 3

Observations:
- Effervesces
- Floats on water
- Moves across surface of water

Question 4

Sodium + water -> Sodium hydroxide + hydrogen

2Na₍s₎ + 2H₂O₍ L₎ -> 2NaOH₍ aq₎ + H₂₍ g₎

Answer 4

Observations:
- Effervesces
- Melts into a ball
- Floats on water
- Moves across surface of water
- Leaves a white trail

Question 5

Lithium + water -> Lithium hydroxide + hydrogen

2Li₍s₎ + 2H₂O₍ L₎ -> 2LiOH₍ aq₎ + H₂₍ g₎

Answer 5

Observations:
- Effervesces
- Floats on water
- Moves across surface of water

Question 6

Lithium + Oxygen -> Lithium oxide

4Li₍s₎ + O₂₍ g₎ -> 2Li₂O₍ s₎

Answer 6

Observations:
- Burns a red flame
Turns U.I purple = alkali

Question 7

Sodium + Oxygen -> Sodium oxide

4Na₍s₎ + O₂₍ g₎ -> 2Na₂O₍ s₎

Answer 7

Observations:
- Burns a yellow flame
Turns U.I purple = alkali

Question 8

Potassium + Oxygen -> Potassium oxide

4K₍s₎ + O₂₍ g₎ -> 2K₂O₍ s₎

Answer 8

Observations:
- Burns a lilac flame
Turns U.I purple = alkali

Question 9

Order of reactivity in group 1 metals + explain

Answer 9

K > Na > Li

K has the most violent effervescing, producing a lilac flame. Next Na has less vigorous effervescing than K but more than Li. Li has the least vigorous effervescing

Question 10

The pattern in reactivity in group 1 metals in terms of electronic configurations

Answer 10

K has the largest atomic radius. Outer e⁻ is furthest from the nucleus. Greater shielding of nucleus by full inner shells of e⁻. Outer e⁻ is lost most easily due to the lower attraction to the nucleus. Therefore the greater the atomic radius the more reactive the group 1 metal