Chemistry 112 The Nature of Covalent Bonding

The Octet Rule in Covalent Bonding  In the case of covalent bonding, electrons are shared between atoms in order to achieve a noble gas configuration  One shared pair of electrons between atoms is a single covalent bond Ex. H 2, Cl 2, H 2 O Ex. H 2, Cl 2, H 2 O

Structural Formulas  The two dots that represent the shared pair can be substituted with a dash  A structural formula represents the covalent bonds by dashes and shows the arrangement of covalently bonded atoms  Any pairs of e- that are not involved in sharing are called lone pairs

Double and Triple Covalent Bonds  Atoms may form double or triple bonds if there is an abundance of single e-  Two shared pairs = double covalent bond  Three shared pairs = triple covalent bond  Some molecules contain double bonds (O 2 ) and some contain triple bonds (N 2 ).

Structural Formulas  Take a look at carbon dioxide…

When lone pairs come in handy…  Sometimes, a lone pair has to be used in the place of a shared pair in order to create a stable octet  These are called coordinate covalent bonds  Ex. CO

Polyatomic Ions  Sometimes, two or more atoms come together and form covalent bonds between each other. They have an overall charge  In the case of ammonium, covalent bonds are used as well as coordinate covalent bonds.  Ex. Page 223

For the remainder of class…  Guided reading for section 8.2  Question 21 – page 229