Problem Set: Polar, Nonpolar, and Ionic Bonds KEY

1. Distinguish between polar and nonpolar bonds. Polar = e- are shared unequally Nonpolar = e- are shared equally

2. Why is an HCl molecule polar while a Cl2 molecule is nonpolar? H & Cl have different electronegativities; therefore they form a polar bond. Cl & Cl have same electronegativity; therefore they form a nonpolar bond.

3. Why do we show only partial charges, and not full charges, on atoms of a polar molecule? Electrons are more attracted to one atom in a polar molecule; however they do not completely transfer from one atom to another.

4a. Which of the following pairs of elements are most likely to form ionic bonds? (show why using electronegativity values) Te and H 2.1 and 2.2 0.1 C and F 2.5 and 4.0 1.5 Ba and F 0.9 and 4.0 3.1 N and F 3.0 and 4.0 1.0 K and O 0.8 and 3.5 2.7

4b. Of the remaining 3 pairs of elements, which one forms the least polar, and which the most polar, covalent bond? (Show why using electronegativity values). Least polar = Te and H (Δ=0.1) Most polar - C and F (Δ=1.5)

Si & O = 1.6 = covalent very polar 5) Classify the bonding between the following pairs of atoms as ionic, covalent very polar, covalent moderately polar, or covalent nonpolar (show with electronegativity values and differences WHY you classify each one): Si & O = 1.6 = covalent very polar N & O = 0.5 = covalent slightly polar Li & O = 2.5 = ionic Br & I = 0.3 = nonpolar O & O = 0.0 = nonpolar Sr & F = 3.1 = ionic As & As = 0.0 = nonpolar N & F = 1.0 = covalent slightly polar Ca & H = 1.2 = covalent very polar H & O = 1.3 = covalent very polar

6a) Write Lewis dot formulas for atoms of strontium, chlorine, and silicon.

6b) Use the appropriate pairs of these atoms to show formation of: an ionic compound and a covalent molecule.

6c) Indicate the polarity of the bond in the covalent molecule (with polarity arrows, or with partial positive and negative charges).

7) Draw Lewis structures for the following covalent compounds, and label the positive and negative ends or regions of the molecule (if applicable): a) H2O

7) Draw Lewis structures for the following covalent compounds, and label the positive and negative ends or regions of the molecule (if applicable): b) O2

7) Draw Lewis structures for the following covalent compounds, and label the positive and negative ends or regions of the molecule (if applicable): c) NCl3 NONPOLAR

7) Draw Lewis structures for the following covalent compounds, and label the positive and negative ends or regions of the molecule (if applicable): d) CO32-

7) Draw Lewis structures for the following covalent compounds, and label the positive and negative ends or regions of the molecule (if applicable): e) HCO3-

7) Draw Lewis structures for the following covalent compounds, and label the positive and negative ends or regions of the molecule (if applicable): f) ClO3-