The number of electrons lost or gained by an atom so as to complete the octet is called ________

Explanation

**Step-by-Step Solution:**

1. **Understanding the Octet Rule**: The octet rule states that atoms tend to gain, lose, or share electrons to achieve a stable electron configuration, typically having eight electrons in their outermost shell.

2. **Identifying Electrons Lost or Gained**: To determine the number of electrons an atom loses or gains, we look at its current electron configuration. For example, Sodium (Na) has an atomic number of 11, with an electron configuration of 2-8-1. It has one electron in its outer shell and will lose that one electron to achieve a stable configuration of 2-8.

3. **Example of Electron Loss**: When Sodium loses one electron, it becomes Na⁺. This loss of one electron allows Sodium to complete its octet configuration, resulting in a stable state.

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