1. Ionic/Covalent/Metallic Bonding Notes

2. Stable or Unstable?
An atom is only stable if it has a full valence shell
If an atom is stable, it will not bond
If an atom is not full, it will bond

3. Compounds
Compounds are formed when 2 atoms of different elements bond together.
Atoms bond to fill their valence shell
An atom will bond with an many atoms as it takes to fill its outer shell
Once the valence shell is full, that atom is stable

4. ION – any atom with more or less electrons than it is
supposed to have*
*Remember that the number of electrons
is supposed to be equal to the number of
Protons if the atom has a neutral charge

5. Types of Chemical Bonds
There are 3 types of chemical bonds:
Ionic Bonds
Covalent Bonds
Metallic Bonds

6. Ionic Bonds Ionic bonds exist between a metal and a nonmetal
When two atoms bond ionically, they gain/lose electrons. Electrons are transferred from one atom to another.
When an atom gains or loses an electron, it becomes an ion

7. Ions Ca +2 +2 +2 +2 +2 +2 +2 It has 2 valence electrons.
How many does it need to be stable?
8…so it can either lose 2 or gain 6. Which is easier?
Calcium is in group 2.
How many valence electrons does it have?
Which other elements would lose 2 electrons?
Group 1 18 2 13 14 15 16 17 3 4 5 6 7 8 9 10 11 12
Losing 2…if it loses 2 electrons, it becomes positive Ca +2 +2 +2 +2 +2 +2 +2

8. Ions +1 +1 +2 +3 +4 -3 -2 -1 +1 -2 +2 +3 +4 -3 -1 +1 -2 +2 +3 +4 -3 -1
Group 1 18 2 13 14 15 16 17 3 4 5 6 7 8 9 10 11 12 +1 +1 +2 +3 +4 -3 -2 -1 +1 -2 +2 +3 +4 -3 -1 +1 -2 +2 +3 +4 -3 -1 +1 +2 +3 +4 -3 -2 -1 +1 +2 +4 -3 -2 -1 +3 +1 +2

9. Ionic Bonds Properties of Ionic Compounds High melting point
Good conductor of electricity
Solid at room temperature

10. Covalent Bonds Covalent bonds exist between NONMETAL and NONMETAL.
Example: H2, H2O, NO3, CH4
Covalent bonds SHARE electrons.
Shared electrons don’t belong to either atom.

11. Covalent Bonds Properties of Covalent Compounds Low melting point
Poor conductor of electricity
Liquid or Gas at room temperature

12. METALLIC BOND bond found in metals; holds metal atoms together very strongly

13. Metallic Bond
Formed between atoms of metallic elements
Electron cloud around atoms
Good conductors at all states, lustrous, very high melting points
Examples; Na, Fe, Al, Au, Co

14. Lewis Structures of molecules
Single Bond: Two atoms sharing one electron pair.
Example: H2
Double Bond: Two atoms sharing two pairs of electrons.
Example: O2
Triple Bond: Two atoms sharing three pairs of electrons.
Example: N2
Resonance Structures: More than one Lewis Structure can be drawn for a molecule.
Example: O3

15. Rules for Drawing Lewis Structures
Carbon dioxide, CO2
Total Number of valence electrons = 4 + (2 x 6) = 16
Double bonds
Rules for Drawing Lewis Structures
First sum the number of valence electrons from each atom
The central atom is usually written first in the formula
Complete the octets of atoms bonded to the central atom (remember that H can only have two electrons)
Place any left over electrons on the central atom, even if doing so it results in more than an octet
If there are not enough electrons to give the central atom an octet , try multiple bonds
E.x. 1. PCl3
Total Number of valence electrons = 5 + (3 x 7) = 26

16. 1. Odd Number of ElectronsNO
Number of valence electrons = 11
Resonance occurs when more than one valid Lewis structure can be written for a particular molecule (i.e. rearrange electrons)
NO2
Number of valence electrons = 17
Molecules and atoms which are neutral (contain no formal charge) and with an unpaired electron are called Radicals O2