Key Concepts: Alkali metals are found in Group 1 of the periodic table. They are soft metals that react vigorously with oxygen to form oxides/peroxides, and with water to form hydroxides and hydrogen gas. Reactions are balanced using coefficients.
Section A: Alkali Metals - The Basics
1. Name four alkali metals. [1]
2. Complete the sentence: Alkali metals are found in Group _____ of the periodic table and have _____ electron(s) in their outer shell. [1]
3. Give three physical properties of alkali metals. [3]
Section B: Reactions with Oxygen
4. Complete the word equation: Alkali metal + oxygen → _________________ [1]
5. Sodium reacts with oxygen to form a white powder. What is the name of this compound? [1]
6. Write the balanced symbol equation for lithium reacting with oxygen. [2]
7. Write the balanced symbol equation for potassium reacting with oxygen. [2]
Section C: Reactions with Water
8. Complete the word equation: Alkali metal + water → _________________ + _________________ [1]
9. When sodium reacts with water, what gas is produced? [1]
10. Describe two observations you would see when sodium reacts with water. [2]
11. Write the balanced symbol equation for sodium reacting with water. [2]
12. Write the balanced symbol equation for lithium reacting with water. [2]
13. Write the balanced symbol equation for potassium reacting with water. [2]
Section D: Balancing Equations - Products and Formulae
14. Rubidium reacts with oxygen to form rubidium oxide. Write the balanced symbol equation. [2]
15. Magnesium (not an alkali metal, but similar) burns in oxygen to form magnesium oxide. Write the balanced symbol equation. [1]
16. Caesium reacts with water to form caesium hydroxide and hydrogen gas. Write the balanced symbol equation. [2]
Section E: Mixed Questions
17. Complete and balance: Na + O₂ → _________________ [1]
18. Complete and balance: K + H₂O → _________________ [1]
19. Lithium metal is stored under oil. Explain why. [2]
20. Explain why alkali metals are more reactive than Group 2 metals. [2]
Total marks: 30
Mark Scheme
1. Any four from: lithium, sodium, potassium, rubidium, caesium, francium [1]
2. Group 1; one [1]
3. Any three from: soft/can be cut with a knife, low density/float on water, shiny when freshly cut, conduct heat/electricity, low melting/boiling points [3]
4. Alkali metal oxide (or oxide) [1]
5. Sodium oxide [1]
6. 4Li + O₂ → 2Li₂O [2]
7. 4K + O₂ → 2K₂O (or 2K + O₂ → K₂O₂ for potassium peroxide also acceptable) [2]
8. Metal hydroxide (or hydroxide); hydrogen [1]
9. Hydrogen [1]
10. Any two from: fizzes/bubbles, floats on surface, melts into a ball, moves around, heat is released/exothermic, sodium melts [2]
11. 2Na + 2H₂O → 2NaOH + H₂ [2]
12. 2Li + 2H₂O → 2LiOH + H₂ [2]
13. 2K + 2H₂O → 2KOH + H₂ [2]
14. 4Rb + O₂ → 2Rb₂O [2]
15. 2Mg + O₂ → 2MgO [1]
16. 2Cs + 2H₂O → 2CsOH + H₂ [2]
17. 4Na + O₂ → 2Na₂O [1]
18. 2K + 2H₂O → 2KOH + H₂ [1]
19. Alkali metals react with water/oxygen/air (moisture); oil prevents contact with these substances/water vapor; reduces fire risk [2]
20. Alkali metals have one electron in their outer shell; it is easier/requires less energy to lose one electron; lower ionization energy [2]