1. Chemical BONDING

2. Chemical Bond
A bond results from the attraction of nuclei for electrons
All atoms trying to achieve a stable octet
IN OTHER WORDS
the p+ in one nucleus are attracted to the e- of another atom
Electronegativity

3. What did the atom of fluorine
say to the atom of
sodium?
You complete me.

4. Two Major Types of Bonding
Ionic Bonding
forms ionic compounds
transfer of e-
Covalent Bonding
forms molecules
sharing e-

5. One minor type of bonding
Metallic bonding
Occurs between like atoms of a metal in the free state
Valence e- are mobile (move freely among all metal atoms)
Positive ions in a sea of electrons
Metallic characteristics
High mp temps, ductile, malleable, shiny
Hard substances
Good conductors of heat and electricity as (s) and (l)

6. It’s the mobile electrons that enable me-tals to conduct electricity!!!!!!

7. IONic Bonding
electrons are transferred between valence shells of atoms
ionic compounds are
made of ions
NOT MOLECULES
ionic compounds are called Salts or Crystals

8. [METALS ]+ [NON-METALS ]-
IONic bonding
Always formed between metals and non-metals
[METALS ]+ [NON-METALS ]-
Lost e-
Gained e-

9. IONic Bonding Electronegativity difference > 2.0
Look up e-neg of the atoms in the bond and subtract
NaCl
CaCl2
Compounds with polyatomic ions
NaNO3

11. Properties of Ionic Compounds
SALTS
Crystals
hard 22oC
high mp temperatures
nonconductors of electricity in solid phase
good conductors in liquid phase or dissolved in water (aq)

12. Covalent Bonding Pairs of e- are shared between non-metal atoms
molecules
Pairs of e- are shared between non-metal atoms
electronegativity difference < 2.0
forms polyatomic ions

13. Always remember atoms are trying to complete their outer shell!
The number of electrons the atoms needs is the total number of bonds they can make.
Ex. … H? O? F? N? Cl? C?
one two one three one four

14. Methane CH4 This is the finished Lewis dot structure
How did we get here?

15. Types of Covalent Bonds
NON-Polar bonds
Electrons shared evenly in the bond
E-neg difference is zero
Between identical atoms
Diatomic molecules

16. Types of Covalent Bonds
Polar bond
Electrons unevenly shared
E-neg difference greater than zero but
less than 2.0
closer to more polar
more “ionic character”

17. non-polar MOLECULES
Sometimes the bonds within a molecule are polar and yet the molecule is non-polar because its shape is symmetrical. H C
Draw Lewis dot first and
see if equal on all sides

18. Polar molecules (a.k.a. Dipoles)
Not equal on all sides
Polar bond between 2 atoms makes a polar molecule
asymmetrical shape of molecule

19. H Cl + -

20. Water is asymmetrical + + H O -

21. Water is a bent moleculeH H

22. Making sense of the polar non-polar thing
BONDS Non-polar Polar Identical Different
MOLECULES
Non-polar Polar
Symmetrical Asymmetrical

23. IONIC bonds ….
Ionic bonds are so polar that the electrons are not shared but transferred between atoms forming ions!!!!!!

24. The End