Groups in the Periodic Table - Revision

Question 1

Describe the reaction of lithium and water.

Answer 1

When lithium is added to water: - it floats - it fizzes steadily and becomes smaller, until it eventually disappears

Question 2

What is the equation for lithium and water?

Answer 2

lithium + water -> lithium hydroxide + hydrogen

2Li _(s) + 2H₂O _(l) -> 2LiOH _(aq) + H_{2 (g)}

Question 3

Describe the reaction of sodium and water

Answer 3

When sodium is added to water:

• it melts to form a ball that moves around on the surface
• It fizzes rapidly
• The hydrogen produced may burn with an orange flame before the sodium disappears

Question 4

What is the equation for sodium and water?

Answer 4

Sodium + water -> Sodium hydroxide + Hydrogen

2Na _(s) + 2H₂O _(l) -> 2NaOH _(aq) + H_{2 (g)}

Question 5

Describe the reaction of potassium and water

Answer 5

When potassium is added to water:

• Potassium melts and floats
• It moves around very quickly on the surface of the water
• The hydrogen ignites isntantly
• The metal is also set on fire, with sparks and a lilac flame
• There is sometimes a small explosion at the end of the reaction

Question 6

What is the equation of potassium and water?

Answer 6

potassium + water -> potassium hydroxide + hydrogen

2K _(s) + 2H₂O _(l) -> 2KOH _(aq) + H_{2 (g)}

Question 7

How do all group one elements react with water and why?

Answer 7

They all react vigorously with water as they have similar electron configurations

Question 8

How does the reactivity of group one elements change as you go down the group?

Answer 8

Group one elements get more and more reactive the further down the group you go

Question 9

Why do group one elements become more reactive the further down the group you go?

Answer 9

As group one elements need to lose only one electron to become stable. Electrons are held to the atom by the attraction between the electron and the protons in the nucleus. Therefore, electrons that are further away will be weaker and electrons that are closer to the nucleus will be stronger.

This means that elements further down the group will lose their electron more easily: this means that they will react more quickly / easily / vigorously.

Smaller atoms with electrons closer to the pull of the nucleus (at the top of the group) will be less reactive as it takes more to lose the electron

Question 10

What is the positive outcome of the flame test with Lithium?

Answer 10

the lithium goes red

Question 11

What is the positive outcome of the flame test with Sodium?

Answer 11

Sodium goes orange (it is so strong that it can mask other colours)

Question 12

What is the positive outcome of the flame test with Potassium?

Answer 12

Potassium goes lilac

Question 13

What is the positive outcome of the flame test with Calcium?

Answer 13

Calcium goes brick red