Module #13

Question 1

Atomic Number

Answer 1

The number of protons in an atom

Question 2

Mass Number

Answer 2

The sum of the numbers of neutrons and protons in the nucleus of an atom

Question 3

Isotopes

Answer 3

Atoms with the same number of protons but different number of neutrons

Question 4

Element

Answer 4

A collection of atoms that all have the same number of protons

Question 5

Radioactive Isotope

Answer 5

An atom with a nucleus that is not stable

Question 6

Order the three constituent parts of the atom in terms of their mass, from least massive to most massive.

Answer 6

Electron
Proton
Neutron

Question 7

What force keeps the electrons orbiting around the nucleus?

Answer 7

The electromagnetic force

Question 8

What is an atom mostly made of?

Answer 8

An atom is mostly empty space.

Question 9

An atom has an atomic number of 34. How many protons and electrons does it have? What is its symbol?

Answer 9

34 electrons and 34 protons. Se is it’s symbol.

Question 10

List the number of protons, electrons, and neutrons for each of the following symbols:
A. Neon-20 (Ne) 
B. 56Fe
C. 139La
D. 24Mg

Answer 10

A. 10 protons, electrons, and neutrons
B. 26 protons and electrons. 30 neutrons
C. 57 protons and electrons. 82 neutrons
D. 12 protons and electrons. 12 neutrons

Question 11

Two atoms are isotopes. The first has 18 protons and 20 neutrons. The second has 22 neutrons. How many protons does the second atom have?

Answer 11

18

Question 12

Which of the following atoms are isotopes?

112Cd, 112Sn, 120Xe, 40Ar, 120Sn, 124Sn

Answer 12

112Sn, 124Sn, 120Sn

Question 13

What is the largest Bohr orbit in a uranium (U) atom, and how many electrons are in it?

Answer 13

The largest Bohr orbit is the 5th one and there are 32 electrons in it.

Question 14

Why is the strong nuclear force such a short-range force?

Answer 14

Since pions have a very short lifetime, the strong nuclear force can only act over a very tiny distance.

Question 15

Determine the daughter products produced in the beta decay of the two radioactive isotopes show below:
A. 98Tc.
B. 125 I

Answer 15

A. 98Ru

B. 125Xe

Question 16

Determine the daughter products produced in the alpha decay of the two radioactive isotopes show below:
A. 212Bi
B. 224Ra

Answer 16

A. 208Ti

B. 220Rn

Question 17

A radioactive isotope goes through radioactive decay, but the isotope’s number of protons and neutrons does not change. What kind of radioactive decay occurred?

Answer 17

Gamma Decay

Question 18

The half life of the radioactive decay of 226Ra is 1,600 years. Is a sample of 226Ra originally had a mass of 10 grams, how many grams of 226Ra would be left after 3,200 years?

Answer 18

2.5 grams

Question 19

Th half-life of the man-made isotope 11Cis 20 minutes.If a scientist makes one gram of 11C, how much will be left in one hour?

Answer 19

0.125 grams

Question 20

Why is radioactive dating unreliable in most situations?

Answer 20

Radioactive dating is usually unreliable because assumptions must be made as to the original condition of the object. These assumptions are usually erroneous.

Question 21

List the three types of radioactive particles discussed in this module in the order of their ability to travel through matter. Start with the particle that cannot pass through much matter before stopping, and end with the one that can pass through the most matter before stopping.

Answer 21

Alpha particles pass through the least amount of matter before stopping, beta particles are next, and gamma rays pass through the most matter before stopping.

Question 22

Nucleus

Answer 22

The canter of an atom, containing the protons and neutrons