Covalent Bonds No more stealing… time to share!

Review Ionic Bonds Positive and negative Ions are attracted to each other. Sort of like the north and south end of a magnet Positive Ions lose electrons Negative Ions gain electrons Happens between Metals and Nonmetals

COVALENT BOND The bond formed by the sharing of electrons The force that holds the atoms together in a covalent bond is the attraction of each atom’s nucleus for the shared pair of electrons.

COVALENT BOND A force that bonds two atoms together by a sharing of electrons Each pair of shared electrons creates a bond Usually occurs between atoms of non-metals Example – Water (H 2 O)Water (H 2 O) OHH

Types of Covalent Bonds Different covalent bond types share a different number of electrons Single Bonds Share 2 Electrons Double Bonds Share 4 Electrons Triple Bonds Share 6 Electrons Water (H 2 O)Carbon Dioxide (CO 2 )Nitrogen (N 2 )

Polar and Nonpolar Covalent Bonds Covalent bonds sometimes do not share electrons equally… Polar = Unequally shared Examples: Water, Ammonia, Carbon Dioxide … and sometimes they do. Nonpolar = Equally shared Examples: Diatomic Molecules Hydrogen (H 2 ) Nitrogen (N 2 ) Oxygen (O 2 ) Fluorine (F 2 ) Chlorine (Cl 2 ) Iodine (I 2 ) Bromine (Br 2 )

Polar Covalent Bonds Some atoms have a greater attraction for electrons than other atoms Due to greater electronegativity When these atoms form a covalent bond, the electrons will not be shared equally This is referred to as a polar covalent bond

Unequal Sharing (Polar Covalent Bond) Why do you think the two Hydrogen atoms share equally, but the Hydrogen and fluorine do not? Bonded hydrogen atoms showing equal sharing of electrons Hydrogen and fluorine bond with an unequal sharing of electrons The unequal sharing of electrons between two atoms that gives rise to negative and positive regions of electric charge Results from an atom’s electronegativity – the ability to attract electrons to itself Electron Cloud

Nonpolar Covalent Bond Some atoms have similar attraction for electrons, so the shared pair(s) will be evenly distributed between each atom There are no “positive” or “negative” sides This is referred to as a nonpolar covalent bond Because there is no separation of charge within the molecule, they have little or no attraction for one another

Nonpolar Covalent bonds atoms share one or more pairs of outer-shell electrons. Oxygen Atom Oxygen Molecule (O 2 ) Oxygen Molecule (O 2 )