.To predict the shape of a molecule: 
(1) Write the Lewis dot structure for the molecule.
(2) Determine the steric number of the central atom.
(3) Decide on the electron pair orientation based on the steric number. 
(4) Consider the placement of lone pairs and any distortions from "regular" shapes.
(5) Name the shape based on the location of atoms attached to the central atom

What is the shape of BeCl₂?
The Lewis dot structure for BeCl₂---

The central Be atom has two bond pairs in its outer shell (SN = 2). Repulsion between these two pairs causes the molecule to be as far apart as possible. The shape of the molecule is linear, and the Cl-Be-Cl bond angle is 180°.