University:
High School
Course:
High School Chemistry
Academic year:

2021
Views:

324

Pages:

2
Author:

Bailee C

Lewis Structures Extra Practice Worksheet – ANSWER KEY Background: Covalent bonding is found between nonmetals. A covalent bond is a shared pair of electrons. Atoms share electrons to obtain a stable octet (except for hydrogen and helium which form a stable duet). The stable octet is also called the noble gas configuration. Molecules can be represented by means of diagrams in which VALENCE electrons are shown as dots around the chemical symbols of the atoms and bonds are represented as lines. Historical Note: The dot formulas are sometimes referred to as Lewis Dot Structures after the chemist who first introduced them in 1916----G.N. Lewis Rules for Molecules: 1. Determine the total number of valence electrons in the formula a. Sum of valance electrons for each atom in the molecule. 2. Central atom will be element with smallest# of valence electrons (excluding H and halogens: a. Aim for symmetry. b. Hydrogen and halogens always bond on the outside. 3. Bond Terminal Atom (update electron count) 4. Add remaining electrons as lone pairs starting with the outside first. a. All atoms want to have 8 valence electrons. Can be any combinations of unshared pairs or bonding pairs. Exceptions: i. Hydrogen – 2 valence electrons (1bond) ii. Helium (He) – 2 valence electrons iii. Boron (B) – 6 valence electrons(3 bonds) 5. Check for octets - Add double or triple bonds as needed to satisfy valence electron requirements 6. DOUBLE AND TRIPLE CHECK - Count total # of valence electrons and compare to original number for the formula (step 1). a. IF TOTAL # VALENCE ELECTRONS IS CORRECT AND ALL BONDING REQUIREMENTS HAVE BEEN MET, THEN THE ELECTRON DOT STRUCTURE IS CORRECT. Draw the Lewis Dot Structures for the following compounds a) Br2 b) HCl c) CH4 d) NH3 e) H2S f) SiF4 g) PF3 h) CO2 i) SO3