1. Answer true or false.

(a) The octet rule refers to the chemical bonding patterns of the first eight elements of the Periodic Table.

(b) The octet rule refers to the tendency of certain elements to react in such a way that they achieve an outer shell of eight valence electrons.

(c) In gaining electrons, an atom becomes a posi­tively charged ion called a cation.

(d) When an atom forms an ion, only the number of valence electrons changes; the number of protons and neutrons in the nucleus does not change.

(e) In forming ions, Group 2A elements typically lose two electrons to become cations with a charge of +2.

(f) In forming an ion, a sodium atom (1₃22₉22_p63_s1) completes its valence shell by adding one elec­tron to fill its 3s shell (12²2s²2p⁶3.9²).

(g) The elements of Group 6A typically react by ac­cepting two electrons to become anions with a charge of -2.

(h) With the exception of hydrogen, the octet rule applies to all elements in periods 1,2, and 3.

(i) Atoms and the ions derived from them have very similar physical and chemical properties.

2. Show how each chemical change obeys the octet rule.

(a) Hydrogen forms 11^- (hydride ion)

(b)Aluminum forms Al³⁺

3. Which of these bonds is the most polar? The least polar?

(a) C-N                (b) C-C                 (c) C-0

4. Complete the chart by writing formulas for the com­pounds formed:

5. What is the charge on each ion in these compounds? (a) CaS (b) MgF₂ (c) Cs₂0 (d) ScC1₃ (e) Al₂S₃

6. Potassium chloride and potassium bicarbonate are used as potassium dietary supplements. Write the formula of each compound.

7. Name these ionic compounds:

(a) NaF        (b) MgS            (c) Al₂0₃

(d) BaC1₂    (e) Ca(HSO₃)₂  (f) KI

(g) Sr₃(PO₄)₂ (h) Fe(OH)₂    (i) NaH₂PO₄

(j) Pb(CH₃COO)₂ (k) BaH₂    (l) (NH₄) ₂1-1PO₄

How many covalent bonds are normally formed by each element?

(a) N          (b) F  (c) C     (d) Br     (e) O

8. Name these binary covalent compounds.

(a) SO₂           (b) SO₃           (c) PC1₃       (d) CS₂

9. Predict the shape of each molecule.

(a) CH₄                        (b) PH₃           (c) CHF₃       (d) SO₂

(e) SO₃                        (f) CC1₂F₂      (g) NH₃        (h) PC1₃

10. Is it possible for a molecule to have polar bonds and yet have no dipole? Explain.

_11. In each case, tell whether the bond is ionic, polar co­valent, or nonpolar covalent.

(a) Br₂            (b) BrCl        (c) HCl      (d) SrF₂

(e) Sia_s            (f) CO             (g) N₂    (h) CsCl