Why are alkali metals not found in nature?

Explanation

### Step-by-Step Solution:

1. **Understanding Alkali Metals**: Alkali metals are the elements found in Group 1 of the periodic table, which includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr). They are characterized by having one electron in their outermost shell (valence shell).

2. **Low Ionization Energy**: These metals have low ionization energies, which means they can easily lose their outermost electron. Ionization energy is the energy required to remove an electron from an atom. The lower the ionization energy, the more readily an atom can lose an electron.

3. **Reactivity with Water**: Alkali metals react vigorously with water to form hydroxides and hydrogen gas. This reaction is highly exothermic, meaning it releases a significant amount of energy, and can be explosive, especially with heavier alkali metals.

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