1. CHEMICAL BONDING & FORMULAS
GHSGT REVIEW
CHEMICAL BONDING & FORMULAS

3. What is a chemical bond?
The attractive force that holds atoms or ions together in a compound.

4. What is the goal when atoms bond?
To obtain a full outer energy level

5. What is the octet rule?
An atom will gain, lose or share electrons to get 8 electrons on the outermost energy level
Full outer energy level = stable atom

6. What are two types of bonds that can occur between atoms?
Ionic
Covalent

7. What is an ionic bond?
A bond formed by atoms that have gained or lost electrons

8. Example: F p F1- p+ 9
no no 10
e e- 10
Na p Na1+ p+ 11
no no 12
e e- 10

9. The ionic compound formed is NaF (sodium fluoride)
Na+ was attracted to F-

10. SODIUM CHLORIDE

11. What is a covalent bond?
A bond formed when atoms share one or more pairs of electrons

12. What happens to the electrons when a covalent bond forms?
Electrons in the outermost energy level are shared between the two atoms
Shown using an electron dot diagrams.

13. COVALENT BOND

14. How can the type of bond between two atoms be predicted?
Metal and nonmetal = ionic bond
Nonmetal and nonmetal = covalent bond
Predict the following:
Mg and F = ionic
O and Cl = covalent
Zn and Zn = metallic

15. What is a polyatomic ion?
An ion made of two or more atoms that are covalently bonded and that act like a single ion; usually forms ionic bonds with other atoms

16. NAME
SYMBOL
Ammonium
NH4+1
Acetate
C2H3O2-1
Carbonate
CO3-2
Chlorate
ClO3-1
Hydroxide
OH-1
Nitrate
NO3-1
Phosphate
PO4-3
Sulfate
SO4-2

17. Compound Names and Formulas

18. What is an oxidation number?
The number of electrons an atom needs to gain, lose, or share when it forms a chemical bond
Pattern of oxidation numbers: or
Ex: Na = +1 Cl = -1
Mg = +2 O = -2

19. How can oxidation numbers be used to write chemical formulas for ionic compounds?
Write the symbols of the atoms
Write the correct oxidation numbers to the right of each symbol
If the oxidation numbers do not add up to zero, write the oxidation number of each atoms as a subscript of the opposite symbol (the symbol of the atom with the positive oxidation number is written 1st in the formula)

20. This is called the “criss-cross” method
Ex: Lithium and fluorine
Li1+ F1- = LiF
Magnesium and chlorine
Mg Cl1- = MgCl2

21. If the compound is covalent, what rules are followed to write the formula?
Prefixes will be used in the name of the formula so just write the symbols of the elements and use the prefix (di, tri, etc.) as the subscript. DO NOT USE OXIDATION NUMBERS TO WRITE THE FORMULAS FOR COVALENT COMPOUNDS!!! DO NOT USE THE “CRISS-CROSS” METHOD!!!!

22. Ex: carbon dioxide = CO2
carbon tetrachloride = CCl4

23. What are the common prefixes?
1 = mono-
2 = di-
3 = tri-
4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-
9 = nona-
10 = deca-

24. What are the rules for naming compounds?
If the compound is a metal and a nonmetal, change the ending of the nonmetal to –ide
Ex: NaBr = sodium bromide
AlCl3 = aluminum chloride

25. Ex: AgNO3 = silver nitrate
If the compound has a polyatomic ion, use the name of the polyatomic ion in the name of the compound.
Ex: AgNO3 = silver nitrate
Na2CO3 = sodium carbonate

26. If the compound is 2 nonmetals, use the prefixes such as di, tri, etc
If the compound is 2 nonmetals, use the prefixes such as di, tri, etc. of the subscript in the name
- also change the ending to –ide
Ex: SiO2 = silicon dioxide
NF3 = nitrogen trifluoride