1. II. Covalent Bonds

2. A. Three Types of Bonds Ionic Bonds Metallic Bonds Covalent Bonds
Between a metal and nonmetal
Electrons are transferred from the metal to the nonmetal
Bond is attraction between positive cations and negative anions
Metallic Bonds
Between two metals
Delocalized electrons attracted to positive metal ions
Sea of Electrons (Electron Sea Model)
Covalent Bonds
Between two nonmetals
Electrons are shared

3. B. Covalent Bond Properties
Covalent bonds involve the sharing of a pair of valence electrons by two atoms

5. B. Covalent Bond Properties Cont.
Covalent bonds form to create a noble gas configuration for each atom

6. C. Molecules
A molecule is a neutral group of atoms joined together by covalent bonds.
A diatomic molecule is a molecule consisting of two atoms

7. D. Diatomic Molecules
7 elements always exist in nature as diatomic molecules:
Hydrogen (H2)
Nitrogen (N2)
Oxygen (O2)
Fluorine (F2)
Chlorine (Cl2)
Iodine (I2)
Bromine (Br2)
Ways to remember:
HONClBrIF
NOF - 7

9. E. Properties of Molecules
Molecules (covalently bonded compounds) tend to have relatively lower melting and boiling points than ionic compounds
Sodium chloride (NaCl) melts at 801°C.
Water (H2O) melts at 0°C and boils at 100° C.

10. F. Molecular Formulas
A molecular formula shows how many atoms of each element a molecule contains.
2 hydrogen
1 oxygen
1 carbon
1 oxygen

11. REVIEW
1. Compared to ionic compounds, molecular compounds tend to have relatively
low melting points and high boiling points.
low melting points and low boiling points.
high melting points and high boiling points.
high melting points and low boiling points.

12. REVIEW
2. A molecule usually consists of
two metal atoms and a nonmetal atom.
two nonmetal atoms and a metal atom.
two or more metal atoms.
two or more nonmetal atoms.

13. REVIEW
3. A molecular formula shows
how many atoms of each element a molecule contains.
a molecule's structure.
which atoms are bonded together.
how atoms are arranged in space.

14. G. Naming Covalent Compounds
1 = mono-
2 = di-
3 = tri-
4 = tetra-
5 = penta-
6 = hexa-
7 = hepta-
8 = octa-
9 = nona-
10 = deca-
Use prefixes to tell how many atoms of an element are present

15. G. Naming Covalent Compounds Cont.
Rules:
Name the elements in the order listed in the formula
Use prefixes to indicate the number of each atom
Do not use the prefix mono- when the first element in the formula contains only one atom
Ex: CO2 = carbon dioxide not monocarbon dioxide
Name of the second element ends in –ide

16. H. Covalent Compound Naming Exceptions
Polyatomic Ions
If the molecule has a charge it is a polyatomic ion. Use the names from the polyatomic ion list (quarter sheet).
NO3– NO N3–
SO32– SO S2–
nitrate
nitrogen trioxide
nitride
sulfite
sulfur trioxide
sulfide

17. Practice
Name the following covalent compounds:
NO2
CF4
H2O
PI3
SF6

18. Practice carbon monoxide Pentacarbon decaoxide dinitrogen tetrasulfide
xenon heptafluoride