Chemistry Exam Review

Question

Name the shape, draw the structure and state the bond angle for each of the following

A) CaCL₂

B) NH₃

C) SF₆

Answer 1

CaCl₂ is an ionic compound.

[ Cl^- ] [ Ca²⁺ ] [ Cl^- ] and put 4 lone pairs of electrons (8 electrons) around each Cl^- ion, and no electrons on the Ca²⁺. The shape is linear with "bond" angles of 180º

NH₃: 8 valence electrons

Put N in the center and 3 N atoms single bonded to the N. Place 1 lone pair of electrons (2 electrons) on the central N atom. That uses all 8 valence electrons.

The shape (geometry) is trigonal pyramidal and the bond angle is <109.5º or ~107º

SF₆: 48 valence electrons and S can violate the octet rule

Place S in the center with 6 F atoms single bonded to the S atom. Place 3 lone pairs of electrons (6 electrons) around each F atom. That uses all 48 valence electrons. The shape (geometry) is octahedral and the bond angle is 90º