Write Lewis dot symbols for atoms of the following elements:
Mg, Na, B, O, N, Br.

Explanation

To write the Lewis dot symbols for the given elements (Mg, Na, B, O, N, Br), we need to identify the number of valence electrons for each atom based on their atomic number and electronic configuration. The Lewis dot symbol represents the valence electrons as dots around the chemical symbol of the element.

### Step-by-Step Solution:

1. **Magnesium (Mg)**:
- Atomic number: 12
- Electronic configuration: 2, 8, 2
- Valence electrons: 2
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