Study Notes
Group 1, also known as the alkali metals, includes elements like Lithium, Sodium, and Potassium, which are soft metals with distinct trends in melting point, density, and reactivity with water.
- Melting Point — Elements in Group 1 have low melting points that decrease down the group.
Example: Lithium has a higher melting point than Potassium. - Density — These elements have low densities and can float on water, with density increasing down the group.
Example: Sodium is less dense than Potassium. - Reaction with Water — Group 1 elements react vigorously with water, forming an alkaline solution and hydrogen gas, with reactivity increasing down the group.
Example: Potassium reacts more vigorously with water than Lithium. - Electron Configuration — Group 1 elements have one electron in their outer shell, making them highly reactive.
Example: Sodium has the electron configuration of 2,8,1.
Exam Tips
Key Definitions to Remember
- Alkali metals are elements in Group 1 of the Periodic Table.
- These metals have one valence electron, making them very reactive.
Common Confusions
- Confusing the trend of melting points with density trends.
- Misunderstanding why reactivity increases down the group.
Typical Exam Questions
- What happens when sodium reacts with water? Sodium reacts with water to form sodium hydroxide and hydrogen gas.
- Why do alkali metals have low melting points? They have weak metallic bonds due to having only one electron in their outer shell.
- How does the density of alkali metals change down the group? The density increases as you move down the group.
What Examiners Usually Test
- Trends in physical properties like melting point and density.
- The reactivity of alkali metals with water.
- Understanding of electron configurations and their impact on reactivity.