Chapter 8 Test Review

• Polar- unequal sharing of electrons• Non-polar - equal sharing of electrons

• Electronegativity- ability to attract electrons

Ionic Compounds Molecular Compounds

Crystal Lattice Molecule

Types of Elements

Metal with non-metal or polyatomic ions

Non-metal with non-metal

Physical State

Solid Solid, liquid or gas

Melting Point High> 300 C

Low <300 C

Solubility in water

Generally high Generally low

Electrical conductivity of solution

Good conductor Poor to none

Properties of Covalent bonds

• Bond length decreases as number of covalent bonds increases.

• Bond strength increases as number of covalent bonds increases

• Bond length increases as number of covalent bonds decreases

• Bond strength decreases as number of covalent bonds decreases.

Sigma and Pi bonds

• Sigma-– Single covalent bond

• Single bond- 1 sigma

• Pi– Multiple covalent bonds

• Double bond- 1 sigma, 1 pi bond• Triple bond- 1 sigma, 2 pi bonds

28. Which diagram correctly depicts the trend in electronegativity?

How many atoms in each formula?• CH3OH• CH4 • PF3 • OF2 • NO2

-

• BH3

• SO4 2-

• CN-

• N2H2

Covalent Bonds

• How many covalent bonds can elements in the following groups form:– Group 1 (alkali metals)– Group 2 (alkali earth metals)– Group 3 – Group 4– Group 5– Group 6– Group 7 (halogens)– Group 8 ( noble gases)

Polar or non-polar

• Shares equally

• Does not share equally

Diatomic Molecules

• List the 7 diatomic molecules:

Naming Molecules

• SiS4

• PCl5

• CCl4

• NO

Writing Formulas

• Sulfur difluoride

• Silicon tetrachloride

• Chlorine trifluoride

• Tetrasulfur heptanitride

Lewis structures

• CH3OH

• BH3

• N2H2

Lewis Structures with polyatomic ions

• SO4 2-

• CN-

Molecular Shapes

• CH4

• PF3

• OF2

• NO2-

Lewis Structures with resonance

• NO3–

• CO32-