1. Electronegativity and Bond Type

2. General Bonds are formed when two atoms share or transfer electrons.
As the atoms move closer together, the electrons from each atom are attracted to the protons of another atom.

3. Bonds Two main types: covalent bonds and ionic bonds
Covalent bonds- electrons are shared equally or somewhat shared.
Ionic bonds- electrons are completely transferred from one atom to another.
This is what causes cations and anions in ionic compounds

4. Electronegativity
How do you determine what bond is formed between two atoms?
Look at the electronegativity values of the atoms.
Electronegativity-the ability of an atom to attract electrons in a chemical bond.

5. Electronegativity
Atoms with higher electronegativity attract electrons more strongly.
If atoms form a bond, the electrons are held close.
If the electronegativity difference is large enough, electrons can be pulled away from the other atom.

6. Electronegativity Each atom has an electronegativity value.
Elements that have low values lose electrons easily.
Elements that have high values gain electrons easily.

7. Bond Types
Little or no difference in electronegativity allows for a covalent bond.
Ex: H2, both atoms have an electronegativity of 2.1
= 0 (no difference in electronegativity)

8. Bond Type
When the electronegativity difference is large, electrons are not shared equally.
The bond is ionic.

9. Bond Types Nonpolar covalent bonds = 0.0-0.39
Ionic bonds = 1.7 or higher

10. Predicting Bond Types
To predict the bond type for two atoms, find the electronegativity value for each element
Subtract the smaller value from the larger.

11. Examples
Predict the bond type in:
HCl
NaCl
CCl4
NH3