Ridha Fathima

1. What Are Alkali Metals?

Alkali metals are very reactive metals found in Group 1 of the periodic table.They all have 1 electron in their outermost shell, which makes them react easily.

List of Alkali Metals

• Lithium (Li)

• Sodium (Na)

• Potassium (K)

• Rubidium (Rb)

• Cesium (Cs)

• Francium (Fr)

General Properties of Alkali Metals

• Soft metals (can be cut with a knife)

• Silvery and shiny when freshly cut

• Very reactive

• Form +1 ions

• Stored in oil to prevent reaction with air or water

• React strongly with water and produce alkaline solutions (bases)

2. TRENDS IN GROUP 1 (ALKALI METALS)

(From Lithium → Cesium)

1. Atomic Size

• Increases down the group

• Because each element has an extra electron shell

2. Reactivity

• Increases down the group

• Outer electron is farther from the nucleus → easier to lose

3. Melting & Boiling Points

• Decrease down the group

• Metallic bonds become weaker as atoms get larger

4. Density

• Generally increases down the group

• Exception: Potassium is less dense than sodium

5. Ionization Energy

• Decreases down the group

• Outer electron requires less energy to remove

6. Hardness

• Metals become softer down the group

• Lithium is the hardest; cesium is very soft

7. Reaction with Water

• Becomes more vigorous down the group

  • Li → gentle reaction

  • Na → strong fizzing

  • K → lilac flame

  • Rb & Cs → explosive

8. Compounds

• Compounds are:

  • White

  • Soluble in water

  • Form colourless solutions