Cliffs AP Chemistry, 3rd Edition

Answer: A

When atoms absorb energy, electrons move from ground states to excited levels. When the
electrons move back to their ground state, they release energy (exothermic) at particular wave-
lengths (or frequencies).

11. An energy value of 3.313 × 10 –12ergs is needed to break a chemical bond. What is the
    wavelength of energy needed to break the bond? (The speed of light = 3.00 × 1010 cm/sec;

Planck’s constant = 6.626 × 10 –27erg ⋅sec.)

A. 5.00 × 10 –4cm

B. 1.00 × 10 –5cm

C. 2.00 × 10 –5cm

D. 6.00 × 10 –5cm

E. 1.20 × 10 –5cm

Answer: D

You need to know two relationships to do this problem. First,

.

.

.

sec

h sec

6 626 10

3 313 10

5 000 10

erg

E erg

27

12

14 1

#:

#

y== - = #

The second relationship you need to know is

.

.

.

5 000 10

300 10

c 600 10

sec

cm sec

14 cm

10

5

:#

#:

m==y = # -

An alternative approach would be to use the relationship

.

..sec

3 313 10

6 626 10 3 00 10

erg

hc erg cm sec

E^12

27 10 1

#

: #::#:

m== -

12. A characteristic of the structure of metallic atoms is that

A. they tend to share their electrons with other atoms

B. their atoms are smaller and more compact than those of nonmetallic elements

C. their outermost orbital of electrons is nearly complete, and they attract electrons

from other atoms

D. the small numbers of electrons in their outermost orbital are weakly held and easily

lost

E. they have heavier nuclei than nonmetallic atoms

Answer: D

Metals lose their electrons readily to become positively charged ions with charges of +1, +2,
or +3.

Part II: Specific Topics