What are the common physical and chemical features of alkali metals?

Explanation

### Step-by-Step Solution

**1. Introduction to Alkali Metals:**
Alkali metals are the elements found in Group 1 of the periodic table, which include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They exhibit unique physical and chemical properties.

**2. Common Physical Features of Alkali Metals:**
- **Softness:** Alkali metals are soft and can be easily cut with a knife. This property is due to their metallic bonding, which is relatively weak compared to other metals.
- **Large Atomic Size:** They have large atomic sizes, which leads to lower densities compared to other metals. This is because the atomic radius increases down the group.
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