Chem 170 Chapter 8

Question 1

According to Coulomb’s law if the separation between two particles of the same charge is doubled, what happens to the potential energy of the two particles?

Answer 1

It is one half as high as it was before the separation

Question 2

Which electron in sulfur is most shielded from nuclear charge?

Answer 2

An electron in the 3p orbital

Question 3

What is the electron configuration for Se?

Answer 3

1s^2 | 2s^2 | 2p^6 | 3s^2 | 3p^6 | 4s^2 | 3d^10 | 4p^4

Question 4

Choose the correct orbital diagram for vanadium
[AR] 4s [||] [ { || } { | } { } { } { } ]
[AR] 4s [ ] [ { | } { | } { | } { | } { | } ]
[AR] 4s [| ] [ { | } { | } { | } { | } { } ]
[AR] 4s [||] [ { | } { | } { | } { } { } ]

Answer 4

[AR] 4s [||] [ { | } { | } { | } { } { } ]

Question 5

Which set of quantum numbers corresponds to an electron in the “4p” orbital?

a) n=4 l=1 ml=0 ms=+1/2
b) n=4 l=3 ml=3 ms=-1/2
c) n=4 l=2 ml=0 ms=+1/2
d) n=4 l=4 ml=3 ms=-1/2

Answer 5

a) n=4 l=1 ml=0 ms=+1/2

“l” is indexed at 0
ex. 0 = s, 1 = p, 2 = d

Question 6

Which element has the smallest atomic radius?
C
Si
Be
F

Answer 6

F(atomic #9)

This is the class formula, wtf!?
atomic radius
Zeff =  Z(atomic #) - S(core electrons)
Zeff = 9(Z) - 2
Zeff = 7

also another trend is, atomic radius increases as you move down and left on the periodic table

Question 7

Which statement is true about effective nuclear charge?
a) outermost electrons efficiently shield one another from nuclear charge.
b) Effective Nuclear charge increases as you move
right across a row in the periodic table.
c) Effective Nuclear charge remains the same as you move
right across a row in the periodic table.
d) Effective Nuclear charge increases and decreases as you move right across a row in the periodic table

Answer 7

b) Effective Nuclear charge increases as you move
right across a row in the periodic table.

Zeff =  Z(atomic #) - S(core electrons)
Zeff = 9(Z) - 2
Zeff = 7

Question 8

Which statement is true about electron shielding of nuclear charge?

a) Outer most electrons efficiently shield one another form nuclear charge.
b) Core electrons efficiently shield one another form nuclear charge.
c) Outermost electrons efficiently shield core electrons from nuclear charge.
d) Core electrons efficiently shield outermost electrons from nuclear charge.

Answer 8

d) Core electrons efficiently shield outermost electrons from nuclear charge.

Nuclear charge comes from the “Nucleus”

Question 9

Which is the correct electron configuration for Fe^2+

a) [Ar]4s^2 3d^6
b) [Ar]4s^2 3d^4
c) [Ar]4s^0 3d^6
d) [Ar]4s^2 3d^8

Answer 9

c) [Ar]4s^0 3d^6

Not sure why exactly, its apparently complex, lets assume that atoms always want to have as little valence and as much core electrons as possible

Question 10

Which species is diamagnetic?

a) Cr^2+
b) Zn
c) Mn
d) C

Answer 10

b) Zn

diamagnetic means there are no unpaired electrons

Question 11

Arrange these atoms and ions in order of increasing radius Cs^+, Ba^2+(5x), I^-

Answer 11

Cs^+ < Ba^2+(5x) < I^-

ignore #s, trend is as you move up and right, ionazation increases

Question 12

Arrange these elements in order of increasing Ionazation energy Cl, Sn, Si

Answer 12

SN < Si < Cl

ionization increases as you move further right and further up the periodic table

Question 13

The ionization energies of an unknown third period element are listed here. Identify the element. 
IE1  = 756 kJ/mol; 
IE2= 1580 kJ/mol;
IE3 = 3230 kJ/mol;
IE4= 4360 kJ/mol;
IE5 = 16100 kJ/mol;

a) Mg
b) Al
c) Si
d) P

Answer 13

c) Si

Small numbers are valence electrons, large #s are core electrons, find a trend, then add them up

Question 14

Which statement is true about trends in metallic character?

a) metallic character increases as you move to the right across a row in the periodic table and increases as you move down a column
b) metallic character decreases as you move to the right across a row in the periodic table and increases as you move down a column
c) metallic character decreases as you move to the right across a row in the periodic table and decreases as you move down a column
d) metallic character increases as you move to the right across a row in the periodic table and decreases as you move down a column

Answer 14

b) metallic character decreases as you move to the right across a row in the periodic table and increases as you move down a column

Metallic character trends the same way atomic radius does!

Question 15

For which element is the gaining of an electron most exothermic?

a) Li
b) N
c) F
d) B

Answer 15

c) F

Question 16

Give the number of valence electrons for Te.

Answer 16

6

Question 17

Which reaction below represents the electron affinity of S?

Answer 17

S(g) + e⁻ → S⁻(g)

Question 18

Identify the most reactive alkali metal with water.

Rb (Rubidium)
Li (Lithium) 
Na (Sodium) 
Cs (Cesium) 
K (Potassium)

Answer 18

Cs

metal gets more reactive as you move down the periodic table

Question 19

Give the set of four quantum numbers that could represent the electron lost to form the K ION from the K atom.

Answer 19

n = 4, l = 0, ml = 0, ms = + 1/2

Question 20

Which of the following represents the change in electronic configuration that is associated with the first ionization of magnesium?

Answer 20

[Ne]3s2 → [Ne]3s1 + e-

Question 21

Choose the valence orbital diagram that represents the ground state of Sr2⁺.

Answer 21

4s [ || ] 4p [ || || || ]

Question 22

Place the following in order of increasing radius.

I- Mg2+ K+

Answer 22

Correct Answer:
Correct
Mg2+ < K+ < I-

Question 23

Give the number of core electrons for F-.

Answer 23

2