Define electronegativity ? How does is vary along a period and along a group .

Explanation

### Step-by-Step Text Solution:

**Step 1: Define Electronegativity**
Electronegativity is defined as the ability of an atom to attract the shared pair of electrons in a covalent bond towards itself. It is a measure of the tendency of an atom to attract electrons when it is part of a compound.

**Step 2: Variation of Electronegativity Along a Period**
As we move from left to right across a period in the periodic table, electronegativity increases. This increase can be attributed to the following reasons:
- The atomic size decreases from left to right due to the increasing positive charge of the nucleus, which pulls the electrons closer.
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