In a coordination entity the central atoms or ions are referred to as:

Lewis acid

The correct answer is option 3. Lewis acid.

In a coordination entity, the central atom or ion is referred to as a Lewis acid.

A coordination entity consists of a central metal atom or ion (known as the central atom) surrounded by a set of ligands (molecules or ions that donate electron pairs to the central atom). In the context of coordination chemistry, the central metal atom or ion acts as a Lewis acid. A Lewis acid is defined as an electron pair acceptor. The central metal ion in a coordination complex accepts electron pairs from the ligands, which act as Lewis bases.

Definitions:

1. Neutral Entity: This term generally refers to a species with no net charge, but it does not specifically describe the role of the central atom or ion in a coordination entity.

2. Lewis Base: A Lewis base is an electron pair donor. In a coordination entity, the ligands act as Lewis bases because they donate electron pairs to the central metal atom or ion.

3. Lewis Acid: A Lewis acid is an electron pair acceptor. The central metal atom or ion in a coordination complex is considered a Lewis acid because it accepts electron pairs from the ligands.

4. Amphoteric Entity: An amphoteric entity can act both as an acid and a base. This term is not typically used to describe the central metal atom or ion in coordination chemistry.

Therefore, the correct term for the central atom or ion in a coordination entity is Lewis acid.