1. Chemical BONDING

2. Chemical Bond A chemical bond results as atoms try to
achieve a stable octet (or duet) in their outer shell just like the noble gases

3. Two Major Types of Bonding
SALTS
Crystals
Ionic Bonding
forms ionic compounds
transfer of e- between valence shells
Covalent Bonding
forms molecules
sharing e- between valence shells

4. One other type of bonding
Metallic bonding
Occurs between atoms of a metal or MIXTURE OF METALS (alloys)
Ex. Al: aluminum foil
Ex. Cu: copper wire
Ex. Steel
Valence e- are mobile (move freely among all metal atoms)
Metallic characteristics
High m.p. temps, ductile, malleable, shiny
Good conductors of heat and electricity

5. Positive ions (nuclei) in a sea of electrons

6. [METAL ]+ [NON-METAL ]-
Ionic Bonds form between
[METAL ]+ [NON-METAL ]-
Lost e-
Gains e-

7. also . . .
The bond to a POLYATOMIC ION
ex. KNO3
ex. NH4Cl

8. Pairs of e- are shared between non-metal atoms
Covalent Bonding
Pairs of e- are shared between non-metal atoms
H2O
NO3-
NaCl

9. In covalent bonding
Electrons can be shared equally which makes the bond NON-POLAR

10. Or
Electrons can be shared Unequally which makes the bond POLAR

11. What determines the polarity of the bond?
Electronegativity
What is Electronegativity?
How strong an atom pulls on electrons of other atoms…….

12. Properties of Ionic Compounds

13. Form crystal lattice structures
because of alternating anions(-) and cations (+)

14. Hard, angular crystals at
room temp ~20oC

15. high melting point temperatures
ex. NaCl
801oC (1,474oF)
Remember H2O melts at 0oC!

16. nonconductors of electricity in solid phase
good conductors in liquid phase or dissolved in water (aq)
Salts & Solution PhET

17. Properties of Molecular Substances
Covalent
bonding
Low m.p. temp and b.p. temps
relatively soft solids as compared to ionic compounds
NONconductors of electricity in any phase

19. The End