Why are ionic compounds usually hard?

Explanation

### Step-by-Step Solution:

1. **Definition of Ionic Compounds**: Ionic compounds are formed when metals react with non-metals, resulting in the transfer of electrons from the metal to the non-metal. This process creates charged ions: cations (positively charged) and anions (negatively charged).

2. **Formation of Ions**: For example, sodium (Na) has an atomic number of 11 and has one electron in its outermost shell. When sodium loses this electron, it becomes a sodium ion (Na⁺) with a total of 10 electrons, achieving a stable electronic configuration similar to neon. Conversely, chlorine (Cl), with an atomic number of 17, gains this electron to become a chloride ion (Cl⁻), also achieving a stable electronic configuration similar to argon.

3. **Electrostatic Forces**: The cations and anions formed are held together by strong electrostatic forces of attraction. This force is the result of the opposite charges of the ions, which attract each other.

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