Summary
Group 1 elements, also known as alkali metals, are soft metals that show trends in melting point, density, and reactivity with water as you move down the group.
- Melting Point — Group 1 elements have low melting points compared to other metals. Example: The melting point decreases as you go down the group from lithium to potassium.
- Density — Group 1 elements have low densities and can float on water. Example: The density increases as you go down the group.
- Reactivity with Water — Group 1 elements react vigorously with water, forming alkaline solutions and hydrogen gas. Example: Reactivity increases down the group, with potassium reacting more vigorously than lithium.
- Reactivity with Air — Group 1 metals react with air to form metal oxides. Example: Potassium burns with a bright flame in oxygen.
Exam Tips
Key Definitions to Remember
- Alkali metals are soft, low-density metals in Group 1.
- Reactivity increases down Group 1.
Common Confusions
- Confusing the trend of melting points with density trends.
- Misunderstanding why reactivity increases down the group.
Typical Exam Questions
- Which alkali metal is most reactive out of the following? Answer: Rubidium
- What happens to the reactivity of Group 1 elements as you go down the group? Answer: It increases.
- How do Group 1 elements react with water? Answer: They react vigorously, producing an alkaline solution and hydrogen gas.
What Examiners Usually Test
- Trends in physical properties like melting point and density.
- Explanation of reactivity trends in terms of electron configuration.