Unit 5- Nuclear Chemistry

Question 1

What is the nucleus made of?

Answer 1

Protons and neutrons that are packed very closely.

Question 2

Define Nucleons

Answer 2

Protons and neutrons are collectively called nucleons.

Question 3

What is the mass # and where does it go?

Answer 3

It is the sum of the neutrons and the protons and it goes on the top left of the symbol.

Question 4

What is the Atomic # and where does it go?

Answer 4

It is the # of protons and it is located on the bottom left.

Question 5

What force holds the nucleus together and how is the strength of that force affected in short distances?

Answer 5

The strong nuclear force holds it together and at short distances, it beasts the electrostatic repulsion present.

Question 6

What is the force that holds the nucleus together?

Answer 6

The strong nucleus force.

Question 7

What does the “mass defect” get converted to?

Answer 7

It gets converted to energy.

Question 8

What is the mass energy equivalence equation?

Answer 8

E=mc^2 (where energy is E, m is the mass of matter being converted, and c is the speed of light in a vacuum= 2.998x10^8 m/s)

Question 9

In problems requiring to use the mass energy equivalence equation, what get plugged for m and what should be done?

Answer 9

The mass defect gets plugged in for m and it should be converted to kg/mol

Question 10

Define Stable Nucleus

Answer 10

A nucleus is stable if it cannot be transformed into another nucleus without the addition of energy.

Question 11

What are some things to note about unstable nuclei?

Answer 11

They can be considered radioactive and they will eventually change enough to become stable.

Question 12

What is a condition that has to be for the stability of the nucleus?

Answer 12

There can only be a certain number of protons and neutrons occupying the space.

Question 13

Isotopes of elements with atomic numbers of what number are unstable?

Answer 13

If they have more than 83 protons, they can be considered unstable.

Question 14

What are the magic numbers when it comes to the number of protons?

Answer 14

2,8,20,28,50,82,126.

Question 15

Define Binding Energy for Nucelon

Answer 15

This is obtained by dividing the total binding energy for the nucleus divided by the number of nucleons in the nucleus. BEPN= Total Binding Energy/ # of Nucleons

Question 16

What is something important to note about calculating for binding energy per nucleon?

Answer 16

The joules must be converted to mega electron volts (MeV); For 1 MeV, there are 1.602x10^-13 J.

Question 17

What are the steps for calculating the binding energy per nucleon?

Answer 17

Determine the mass defect of the nuclide. Calculate the binding energy for one nucleus from the mass defect using the mass-energy equivalence equation. Convert the binding energy in joules per nucleus into units of MeV per nuclide. Determine the biding energy per nucleon by dividing the total binding energy by the number of nucleons in the atom.

Question 18

When do fusion and fission tend to happen respectively?

Answer 18

Fusion happens when lighter nuclei come together and fission happens when heavy nuclei are breaking into lighter ones.

Question 19

What is the border for the fusion and fission graph?

Answer 19

Fe

Question 20

What are the different types of particles present in nuclear reactions?

Answer 20

Alpha-Beta-Positron-Proton-Neutron-Gamma Ray ABP-PNG

Question 21

What is the symbol for the alpha particle?

Answer 21

4/2 A or 4/2 He

Question 22

What is the symbol or the beta particle?

Answer 22

0/-1 e or 0/-1 B

Question 23

What is the symbol for the positron?

Answer 23

0/+1 e

Question 24

Define Radioactive Decay

Answer 24

Refers to the spontaneous transformation of an unstable nuclide into another. The unstable nuclide is called the parent nuclide and the nuclide that results from decay is known as the daughter nuclide.

Question 25

What is the symbol for the gamma ray?

Answer 25

0/0 Y

Question 26

Is there a change in mass number of the atomic number during the emission of a gamma ray?

Answer 26

NO

Question 27

In what circumstances does the gamma ray get emitted?

Answer 27

Only when the parent nuclide gets excited and it comes down to its ground state.

Question 28

In what types of substances does alpha decay occur in?

Answer 28

Heavier nuclei .

Question 29

Define Electron Capture

Answer 29

Occurs when one of the inner electrons in an atom is captured by the atom’s nucleus.

Question 30

What are the equations that need to be known for radioactive decay?

Answer 30

Ln NT/N0 = -lambda(t) ; Nt= N0e^-(lambda)(t)

T= -1/lambda x ln NT/N0

Question 31

What is the equation that needs to be known for the half-life?

Answer 31

T 1/2= 0.693/lambda

Question 32

What is the relationship between the unit of lambda and the unit of the half-life?

Answer 32

Lambda is the inverse unit of the half-life.

Question 33

What is the carbon-14 and the carbon-12 ratio for organisms?

Answer 33

It is constant for organisms and matches the levels in the atmosphere.

Question 34

What is something to note about the n:p ratio regarding alpha decay?

Answer 34

The daughter nuclei has a higher n:p ratio compared to the parent one.

Question 35

What sort of conversion happens in beta decay?

Answer 35

A neutron converts to a proton and a beta particle. BNP

Question 36

How does positron emission affect the n:p ratio?

Answer 36

It increases the ratio.

Question 37

What substance has the highest binding energy per nucleon?

Answer 37

Iron

Question 38

What sort of n:p ratio will be present in the heavier elements?

Answer 38

1.5

Question 39

What happens to the n:p ratio for substances that are heavier than others?

Answer 39

For heavier substances, the n:p ratio increases.