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100 Chapter 3 Chemical Bonds

UWL tnteractive versions of these problems may be assigned in OWL.

Orange-numbered problems are applied.

Section 3.2 What ls the Octet Rule? 3.17 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 ofcertain elements to react in such a way that they achieve an outer shell ofeight valence electrons.

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

(d) When an atom forms an ion, only the number of . valence electrons changes; the number ofprotons

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 (1s22s22p63s1) completes its valence shell by adding one elec- tron to filI its 3s shell (k22s22p63s2).

(g) The elements of Group 6A typically react by ac- cepting 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.

3.18 How many electrons must each atom gain or lose to acquire an electron configuration identical to the noble gas nearest to it in atomic number? (a) Li (b) Cl (c) P (d) Al (e) Sr (f) S (e) Si (h) O

3.19 Show how each chemical change obeys the octet rule. (a) Lithium forms Li* (b) Oxygen forms O Show how each chemical change obeys the octet rule. (a) Hydrogen forms H- (hydride ion) (b) Aluminum forms Al3+

3,2L Write the formula for the most stable ion formed by each element. (a) Mg (b) F (c) (d) s (e) K (I)

3.22 Why is Li- not a stable ion? 3.23 Predict which ions are stable:

(a) I- (b) Se2+ (c) Na* (d) 52- (e) tr12+ (fl Ba8+ 3,24 Predict which ions are stable:

(a) Br2- (b) C4- (c) Ca* (d) Ar* (e) Na* (I) Cs*

a

3.25 Why are carbon and silicon reluctant to foil bonds?

3.26 Table 3.2 shows the following ions of co14m and Cu2*. Do these violate the octet rule?

Section 3.3 How Do We Name Anions and Cations? 5.27 Answer true or false.

(a) For Group 1A and Group 2A elements,fte of the ion each forms is simply the nare element followed by the word ion; for Mg2* is named magnesium ion.

(b) H+ is named hydronium ion, and H is hydride ion.

(c) The nucleus of H* consists of one proton neutron.

(d) Many transition and inner transition form more than one positively charged irn I

(e) In naming metal cations with two diffemed charges, the suffix -oas refers to the ion a charge of + 1 and -ic refers to the ion wift charge of +2.

(f) Fe3* may be named either iron(III) ion or (g) The anion derived from a bromine atom is

bromine ion. (h) The anion derived from an oxygen atomis

named oxide ion. (i) HCO; is named hydrogen carbonate ion- .

0) The prefrx bi- in the name "bicarbonate'im indicates that this ion has a charge of -2-

(k) The hydrogen phosphate ion has a charge and the dihydrogen phosphate ion has a charge of +2.

(l) The phosphate ion is PO3a-. (m) The nitrite ion is NOz , and the nitrate

ion is NO3-. (n) The carbonate ion is CO32-, and the

carbonate ion is HCO3-.

3.28 Name each polyatomic ion. (a) HCO; (b) NO; (c) SOr'- (d) HSO4- (e) HzPOa-

Section 3.4 What Are the Two Major Types

participating in the bond acquires an outer<{ electron configuration matching that of the{ gas nearest to it in atomic number. I

(b) Atoms that lose electrons to achieve a filled t valence shell become cations and form ionic bonds with anions.

of Chemical Bonds? : 3.29 Answer true or false. j

(a) According to the Lewis model of bondi.g, d bond together in such a way that each atom {

AI Br

,-.-r lll - '-' - -----'--- - - -'

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