The Nature of Covalent Bonding

Covalent Compounds 2 nonmetals form a bond Electrons are shared to form the noble gas configuration Ex: H2

Drawing Covalent Molecules In order to do this you need to know what a Lewis Dot Diagram is!!!! Lewis Dot Diagram- Write the chemical symbol for the element and use dots to represent valence electrons. Ex: Mg: Remember: there is a maximum of 8 dots that you can draw…can you think why?

Single Bonds Single Covalent Bond- 2 atoms held together by sharing one pair of electrons. Example: H:H or H-H The dash represents the single bond

Structural Formula- represents covalent bonds by dashes and shows the arrangement of covalently bonded atoms. Example: F2 * NOTE: ALL HALOGENS ARE DIATOMIC MOLECULES!!!*

The Shapes of Molecules VSEPR – valence shell electron pair repulsion model Provides a way to predict the shapes of molecules This is determined by drawing a dot diagram for the molecule

Electron Pairs have 2 types Shared Pairs- pair of electrons in a covalent bond (dashed line) Lone Pairs- pair of valence electrons that is not shared between atoms, called lone pair or non-bonding pair(dots)

Example #1: H2O Lewis Dot Structure: Structural Formula:

Example #2: NH3 Lewis Dot Structure: Structural Formula:

Example #3: CH4 Lewis Dot Structure: Structural Formula:

Double & Triple Covalent Bonds Double covalent bond- a bond that there are 2 shared pairs of electrons (4 electrons) Ex: O2 Triple covalent bond- a bond that there are 3 shared pairs of electrons (6 electrons). Ex: N2

Stability The more shared pairs it has…the MORE STABLE THE MOLECULE!

What type of bonds do these form? 1. CO2 2. HCN 3. Br2