Ch 2 Problems

Question 1

Specify the # of protons, neutrons, electrons in atom chromium-52

Answer 1

Atomic mass 52

Atomic mass = # protons + # neutrons

Chromium has 24 protons
52=24+x
X=28

24 protons & 28 neutrons & 24 electrons

Question 2

Ion N^(-3) has ____ protons and ___ electrons

Answer 2

Nitrogen has atomic # 7

For total charge to be -3, it gains 3 more electrons than protons

Therefore 7 protons 10 electrons

Question 3

What isotope has 17 protons and 18 neutrons?

Answer 3

Protons stay the same; in an isotope the only thing that changes are neutrons

Element with atomic # 17 is chlorine (Cl)

Mass number is #protons and #neutrons which is = 17+18 = 35

Chlorine-35

Question 4

Which element has mass 41 and atomic number 20?

Answer 4

Calcium (Ca)

Question 5

How many neutrons are in chlorine -36?

Answer 5

Chlorine’s atomic # is 17.

So 36-17=19

19 neutrons

Question 6

94. 93% 31.07207 amu
95. 7640% 32.97146 amu
96. 290% 33.96786 amu
97. 6*10^-2 % 35.96709 amu

Atomic mass of element?

Answer 6

Take weighted average to get atomic mass

32.07 amu

Element name Sulfur (S)

Question 7

Chlorine-35
Chlorine-37

Which is more abundant?

Answer 7

Chlorine-35

Atomic mass of chlorine is 35.45 which is closer to chlorine-35

Question 8

Relative abundance of boron-10?

Boron-10 10.01294 amu
Boron-11 11.00931 amu

Answer 8

Set mass weight in weighted average for boron-10 to x. Set mass weight for boron-11 to x-1

Calculate weighted average equal to atomic mass of boron

19.9 or 20%

For boron-11 it is 80.1 or 80%

Question 9

K is a ___

Answer 9

Atomic element

Question 10

Ar is a ____

Answer 10

Atomic element

Question 11

N2 is a ____

Answer 11

Molecular element

Question 12

S8 is a ___

Answer 12

Molecular element

Question 13

KCl is a ____

Answer 13

Ionic compound

Question 14

FeCO3 is a ____

Answer 14

Ionic compound

Question 15

NH3 is a ____

Answer 15

Molecular compound

Question 16

SO2 is a _____

Answer 16

Molecular compound