1. Chemical Formulas and Chemical Bonding
Obj:
Identify how many of each element are in a compound based on the chemical formula.
Explain why and how elements bonds
Chemical Formulas and Chemical Bonding

2. Chemical Formulas Shows: How many elements are in a compound
Ratio of atoms in a compound

3. Chemical Bonds
Strong attractive force b/t atoms or ions in a molecule or cmpd.
Formed by:
Transferring e- (losing or gaining)
Sharing e-

4. Stability Octet Rule: Most form bonds to have 8 valence e-
Full outer energy level
Stability is the driving force behind bond formation

5. What Determines Bonding?
Elements bond based on the amount of e- they have and the charge they have.

6. Ionic Bonds Formed b/t two ions by the transfer of electrons
Metal interact with nonmetals
Positive ions form when the number of e- are less than the number of protons
Group 1 metals  ion 1+
Group 2 metals  ion 2+
Group 13 metals  ion 3+

7. Transferring e-

8. Check for Understanding
1. Number of valence e- in Aluminum
A. 1 e- B. 2 e- C. 3 e-
2. Change in e- for octet
A. lose 3 e- B. gain 3 e- C. gain 5 e-
3. Ionic charge of Al
A. 3- B. 5- C. 3+

9. Check for Understanding
Give the ionic charge for each of the following:
12 p+ and 10 e- O
50 p+ and 46 e-
15 p+ and 18 e-

10. Nonmetal ions Nonmetals in 15, 16 and 17 gain e- from metals
Nonmetals add e- to achieve octet arrangement
Nonmetal ionic charge:
-3, -2, or -1

11. Ionic Bonds

12. Ionic Bonds
Ionic bond—e- from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charge particles or ions

13. Covalent Bonds
Formed by the sharing of e-

14. Covalent Bonds
Between nonmetallic elements of similar electronegativity.
Formed by sharing e- pairs
Stable non-ionizing particles
Bonds in all polyatomic and diatomic are all covalent bonds

15. Polar vs. Nonpolar
Nonpolar covalent bonds—when e- are shared equally

17. Polar Covalent Bonds
Formed when e- are shared but shared unequally

18. Water is a polar molecule because oxygen is more electronegative than hydrogen, and e- are pulled closer to oxygen

19. Metallic Bonds Bond found in metals
Holds metal atoms together very strongly
Formed b/t atoms of metallic elements
Form alloys:
They do not combine with other metals
Alloy—solution of a metal in a metal (steel, brass, bronze and pewter)

20. Formula Weights
Sum of atomic masses

21. Check for Understanding
Compute the mass of the following cmpds. Round to the nearest tenth and state the type of bond
NaCl
C2H6
Na (CO3)2