8/12/2019 Solutions to CHEM 1123 Unit 2 Sample Problems

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CHEM 1123

Solutions to Unit 2 Sample Problems

Dr. Steve Shore

1. No, H is a nonmetal despite being in Group 1A.

2. V _metal______ As _metalloid_____ Ne _nonmetal___ H _nonmetal____

3. V _T__ Ar _R__ Si _R__ Ag _T__ Sm _L__ Pu _A__

4. Br __halogen_____ Cs _alkali metal__________

Xe __noble gas____ Cl _halogen__________

N __none of these__ Ba _alkaline earth metal_____

5. Metals: are shiny (or have luster), are ductile, are malleable, are good conductors of heat andelectricity. (Most have high melting points.)

Nonmetals: are not lustrous, not ductile, not malleable (the solid nonmetals are brittle; many are

gases at room temperature). They are poor conductors of heat and electricity (they areinsulators).

6. Fe: Function: involved in oxygen transport (part of hemoglobin); cofactor in many enzymes.Source: red meat, fortified cereal, green leafy vegetables.

Zn: Function: Cofactor in many enzymes involved in energy production and DNA replication.

Source: oysters, crab, beef, organ meat, whole grains

Mn: Function: Cofactor in enzymes involved in fat and carbohydrate metabolism.Source: Whole grains, wheat germ, legumes, pineapple, figs

7.

SymbolAtomic

number# of protons # of neutrons Mass number

# of

electrons

31 31 40 71 31

44 44 59 103 44

41 41 52 93 41

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8. Strontium has 2 valence electrons (Group 2A). Electron-dot symbol:

Arsenic has 5 valence electrons (Group 5A). Electron-dot symbol:

Bromine has 7 valence electrons (Group 7A). Electron-dot symbol:

9. a. O2-

= oxide ion

b. P3-

= phosphide ion

c. K+ = potassium ion

d. Zn2+

= zinc ion

e. Cu2+

= copper(II) ion

10. Al = 1, H = 3, S = 3, O = 12

11. a. Na3P = sodium phosphide

b. Li2S = lithium sulfide

c. Fe2S3= iron(III) sulfide

d. Cu2O = copper(I) oxide

12. a. chromium(II) sulfide

b. chromium(III) nitratec. calcium sulfite

d. Sr3N2

e. Fe(ClO3)3

f. sodium bicarbonate or sodium hydrogen carbonate

g. carbon disulfide (covalent compound use prefixes)

h. CCl4 (covalent compound use prefixes)

i. SBr6 (covalent compound use prefixes)

j. dinitrogen pentoxide (covalent compound use prefixes)

13.

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14. a. + I-Cl - difference = 3.162.66 = 0.5 big enough difference to be a polar bond

b. + H-O - difference = 3.442.20 = 1.24 definitely polar

c. + C-F - difference = 3.98 2.55 = 1.43 definitely polar

d. Mg-Cl difference = 3.161.31 = 1.85 ionic (full charges likely rather than )

15. a. 4 sig. figs. b. 2 sig. figs. c. 4 sig. figs.

16. a. 100 cm = 1 m or 1 cm = 0.01 m

b. 10 dm = 1 m or 1 dm = 0.1 m

c. 1000 mL = 1 L or 1 mL = 0.001 L

17. a.

b.

c.

d.

18.

(Note: 4 doses would be an exact numberit would not affect the number of sig. figs. in the

answer. You are limited by the 5.0 mL measured volume. The decimal after the zero in 80

indicates the zero counts as a sig. fig.)