2aGroup 1 (alkali metals) – lithium, sodium and potassium

Question 1

Question: What are the alkali metals in Group 1 that you need to know?

Answer 1

Answer: Lithium (Li), Sodium (Na), and Potassium (K).

Question 2

Question: What are the similarities in the reactions of Group 1 metals with water?

Answer 2

They all react with water to produce hydrogen gas and a metal hydroxide.

They float, fizz, and move on the water surface.

General equation: Metal + Water → Metal Hydroxide + Hydrogen

Question 3

Question: Write the word and balanced chemical equations for lithium, sodium, and potassium with water.

Answer 3

Lithium: Lithium + Water → Lithium Hydroxide + Hydrogen2Li (s) + 2H₂O (l) → 2LiOH (aq) + H₂ (g)

Sodium: Sodium + Water → Sodium Hydroxide + Hydrogen2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂ (g)

Potassium: Potassium + Water → Potassium Hydroxide + Hydrogen2K (s) + 2H₂O (l) → 2KOH (aq) + H₂ (g)

Question 4

Question: What evidence suggests that Group 1 elements are a family of elements?

Answer 4

They share similar properties, such as reacting with water to produce hydrogen and a hydroxide. Their reactions become more vigorous as you move down the group.

Question 5

Question: How do the reactions of lithium, sodium, and potassium with air and water show a trend in reactivity?

Answer 5

Lithium: Reacts slowly, forming a dull oxide layer.

Sodium: Reacts more quickly, forming a white oxide layer.

Potassium: Reacts the most rapidly, often producing a lilac flame.

Question 6

Question: What is the trend in reactivity as you move down Group 1, and why?

Answer 6

Answer: Reactivity increases down the group because the outer electron is farther from the nucleus, making it easier to lose.

Question 7

Question: Predict the properties of rubidium and cesium based on the trends in Group 1.

Answer 7

: Rubidium and cesium are more reactive than potassium. They would react violently with water, producing hydrogen gas and metal hydroxides.

Question 8

Practical: Investigating the Reactions of Group 1 Metals with Water

Method:

Answer 8

Drop a small piece of lithium, sodium, and potassium into separate beakers of water.

Observe the reaction, noting speed, fizzing, flame (if any), and gas production.

Question 9

Practical: Investigating the Reactions of Group 1 Metals with Water

Results and conclution

Answer 9

Results:

Lithium: Fizzes slowly and moves on the surface.

Sodium: Fizzes rapidly, melts into a ball, and moves quickly.

Potassium: Reacts violently, often producing a lilac flame.

Conclusion:

Reactivity increases as you move down Group 1.