1. Ionic vs. Covalent Bonding
GPS Standards: SC3. Students will use the modern atomic theory to explain the characteristics of atoms. e. Compare and contrast types of chemical bonds (i.e. ionic, covalent).
SC1. Students will analyze the nature of matter and its classifications.
c. Predict formulas for stable ionic compounds (binary and tertiary) based on balance of charges.
11/5/13

2. Why bond. Most atoms are not stable by themselves
Why bond? Most atoms are not stable by themselves. A chemical bond provides stability for both atoms involved by lowering the potential energy of both atoms.
chemical bond = a mutual electrical attraction between the nuclei (positive) and valence electrons (negative) of different atoms that binds the atoms together.
valence electrons = electrons located in the outermost (last) s and p sublevels of an atom (max of 8e-).
all atoms want 8 valence electrons for maximum stability (like a noble gas), so they either lose, gain, or share e- from their last s and p sublevels to get 8.
three types of bonds:
ionic bond = bond that results from the electrical attraction of large numbers of cations (pos. ions) and anions (neg. ions). Electrons transfer from one atom to another in an ionic bond. He 1 2
Valence e- # 3 4 5 6 7 8 +1 +2
Ion Charge +3 ±4 -3 -2 -1

3. three types of bonds:
ionic bond = bond that results from the electrical attraction of large numbers of cations (pos. ions) and anions (neg. ions). Electrons transfer from one atom to another in an ionic bond.
polar covalent bond = results from unequal sharing of electrons btwn atoms.
non-polar covalent bond = results from equal sharing of electrons btwn atoms.

4. polar covalent bond = results from unequal sharing of electrons btwn atoms.
non-polar covalent bond = results from equal sharing of electrons btwn atoms.

5. to distinguish between each type of bond:
determine values for the two elements in the bond (use the electronegativity table)
subtract the lower value from the higher value
use electronegativity range to determine the polarity
Differences between 0 and 0.3 indicate non-polar covalent bonds, from 0.4 to 1.7 indicate polar covalent bonds, and from 1.8 to 3.3 indicate ionic bonds.
Ionic bonds mainly form between a metal/metalloid and a nonmetal.
Covalent bonds mainly form between two nonmetals (remember, H = nonmetal) H
2.1
Electronegativity Table He -- Li
1.0 Be
1.5 B
2.0 C
2.5 N
3.0 O
3.5 F
4.0 Ne Na
0.9 Mg
1.2 Al Si
1.8 P S Cl Ar K
0.8 Ca Sc
1.3 Ti V Cr Mn Fe Co Ni Cu
1.9 Zn
1.6 Ga Ge As Se
2.4 Br
2.8 Kr Rb Sr Y Zr
1.4 Nb Mo Tc Ru
2.2 Rh Pd Ag Cd
1.7 In Sn Sb Te I Xe Cs
0.7 Ba La
1.1 Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn Fr Ra
EN Range
Non-polar
Polar
Ionic

6. Ionic bonds mainly form between a metal/ metalloid and a nonmetal
covalent bonds mainly form between two nonmetals (remember, H = nonmetal)
Non-polar covalent bonds exist in diatomic molecules, and a few others
practice: are the bonds I, NPC, or PC?
sulfur and hydrogen
oxygen and cesium
sulfur and chlorine
calcium and chlorine
bromine and chlorine
diatomic oxygen
magnesium and fluorine
carbon and hydrogen
aluminum and nitrogen
2.5 – 2.1 = 0.4 = PC
3.5 – 0.7 = 2.8 = I
3.0 – 2.5 = 0.5 = PC
3.0 – 1.0 = 2.0 = I
3.0 – 2.8 = 0.2 = NPC
3.5 – 3.5 = 0 = NPC
4.0 – 1.2 = 2.8 = I
2.5 = 2.1 = 0.4 = PC
3.0 – 1.5 = 1.5 = PC