6.1 Introduction to Chemical Bonding Ch. 6 Bonding 6.1 Introduction to Chemical Bonding

Chemical Bonds atoms rarely exist alone when atoms are bonded together, they have less potential energy and are more stable What is potential energy? chemical bond – mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together

Ionic Bonds results from electrical attraction between large numbers of cations and anions atoms donate or accept electrons from each other

Covalent Bonds results from sharing of electron pairs between two atoms the electrons shared belong to both atoms

Covalent Bonds when electrons are shared unevenly Polar Covalent Nonpolar Covalent when electrons are shared evenly

Ionic vs. Covalent

Ionic vs. Covalent bonding usually does not fall in one category or the other, but somewhere in between type of bond depends on the elements differences in electronegativities

Ionic vs. Covalent Difference in electronegativities Percent Ionic Character Ionic > 1.7 > 50 % Polar Covalent 0.3 – 1.7 5 – 50 % Nonpolar Covalent 0 – 0.3 0 – 5 %

Polarity Polar- uneven distribution of charge Show partial charges on structure by using  (lowercase delta)

Determine whether each of the following bonds will be: ionic, polar covalent, OR nonpolar covalent

S and H 2.5-2.1=0.4 polar covalent S and Cs 2.5-0.7=1.8 ionic C and Cl 3.0-2.5=0.5

Cl and Ca 3.0-1.0=2.0 ionic Cl and O 3.5-3.0=0.5 polar covalent Cl and Br 3.0-2.8 nonpolar covalent

Patterns What kind of patterns do you see? metals + nonmetals = ionic nonmetals + nonmetals = covalent