1. Chemical Bonding
Chapter 20

2. Stability Achieved by Bonding
Elements other than Group 18 achieve stability (full set of valence electrons) by bonding and forming compounds
3 types of chemical bonds
Ionic
Covalent
Metallic

3. 1. Ionic Bonding Formed between metals and nonmetals
Formed between positive and negative ions
One atom gains electrons from the other atom that loses

4. Naming Binary Ionic Compounds
Name metal first (positive ion)
Then add the name of the nonmetal (negative ion) but change the ending to “ide”
Ending is usually the last syllable
Example: sodium (Na) and chlorine (Cl)
Name: Sodium Chloride
Chemical Formula: NaCl

5. Practice Problem 1:
Name the ionic compound shown below: MgF2 Magnesium fluoride

6. Practice Problem 2:
Name the ionic compound shown below: Li2O Lithium oxide

7. Writing Chemical Formulas for Binary Ionic Compounds
Write the symbol for each element with it’s oxidation number (charge)
Remember: write metal first
Chemical formulas of ionic compounds are always neutral (so oxidation numbers must balance)
Add subscripts to the symbols for the ions until the sum of the charges is equal to zero
No subscripts are needed if only one ion is present

8. Example: Calcium Chloride
Ca+2 Cl-1
CaCl2

9. Practice Problem 3:
Write the chemical formula for aluminum bromide.

10. Practice Problem 4:
Write the chemical formula for magnesium nitride.

11. Practice Problem 5
Write the chemical formula for calcium oxide.

12. Basic Properties of Ionic Compounds
Electrolytes
Conduct electricity in aqueous solution
Dissolve well in water
Solid crystal at room temperature
Strong interparticle forces

14. 2. Covalent Bond Formed between 2 nonmetals Atoms share electrons
Single, double, triple bonds
The number of open positions that have 1 valence electron tells the number of bonds that element can make
Example:
Carbon
Bromine
hydrogen

15. To name a covalent compound, same as ionic naming except you use prefixes to represent how many atoms of each element you have
1 = mono
2 = di
3 = tri
4 = tetra
5 = penta
6 = hexa
7 = hepta
8 = octa
9 = nona
10 = deca

16. Naming Molecular Compounds
write the name of the element that is the least electronegative first.
Example: SO2
sulfur

17. 2. Write the name of the second element and change the ending to “ide” Example: SO2 sulfur oxide

18. 3. Add a prefix to the beginning of each element’s name to indicate how many of atoms of each there are (exception: you do not write the word mono in front of the first element if there is only one). Example: SO2 sulfur dioxide

19. Example: CO Carbon Carbon oxide Carbon monooxide
If the vowel combination o-o or a-o appear next to each other in the name, the first of the pair is omitted
Example: CO
Carbon
Carbon oxide
Carbon monooxide
 carbon monoxide

20. Practice Problem 1
Name the following molecular compound: CCl4

21. Practice Problem 2:
Name the following molecular compound: N2O4

22. Exceptions to the naming rule:
Hydrocarbons/Organic compounds/Alkanes
Compounds made only of carbon and hydrogen and single bonds
CH4 = methane
C2H6 = ethane
C3H8 = propane
C4H10 = butane
C5H12 = pentane
C6H14 = hexane
C7H16 = heptane
C8H18 = octane
C9H20 = nonane
C10H22 = decane

23. Exceptions to the naming rule:
Common Names
H2O = water
NH3 = ammonia

24. Writing Molecular Formulas
Name tells you the elements present and the number of each atom to write as subscripts.
Example: nitrogen trifluoride

25. Practice Problem 3:
Write the molecular formula for tetraphosphorus decoxide.

26. Practice Problem 4:
Write the molecular formula for dinitrogen monoxide.

27. Properties of Covalent Compounds
Lower melting point than ionic compounds
Most are liquids or gases
If solid, not as hard as ionic compounds
Weak interparticle forces between molecules
Do not conduct electricity or heat

28. 3. Metallic Bonds Formed between atoms of metals only
Metal cations and mobile electrons
Occurs in pure metals (Fe)