Topic 2: Nuclear Chemistry

Question 1

How is the stability of an isotope determined?

Answer 1

-Stability depends on the ratio of protons to neutrons in nucleus. Stable= 1:1
-Unstable nuclei usually have more neutrons than protons

Question 2

What does it mean if a nucleus is unstable? What results in an unstable nucleus ?

Answer 2

-Unstable nuclei usually have more neutrons than protons
-will spontaneously decay, emitting radiaton
-reason for being susceptible to radioactive decay is that the irregular ratio of P to N is not as effective at holding nucleus together

Question 3

Rate of decay

Answer 3

know as HALF LIFE
-each isotope has a specific half life
-constant, can never be changed
-measures the time for 1/2 of the isotope to decay
-the half life will never decay to 0

Question 4

Elements are radioactive if their atomic number is higher than what?

Answer 4

All elements with an atomic number (protons) higher than 83 are radioactive

Question 5

Where/how does transmutation occur and what results?

Answer 5

1. occurs in the nucleus
2. naturally or artificially
   -artificial transmutation involves bombarding nucleus by high energy particles
   -spontaneous (natural) can involve release of particles from nucleus
3. RESULTS: atom turns into a different type of atom, therefore becoming a different element

Question 6

What’s the cause and effect of nuclear fission?

Answer 6

Cause (can be):”shooting” nucleus with a neutron

Effect: nucleus is split
-products are not radioactive wastes
-large atom splits into 2 or more smaller
-energy is a product

Question 7

What is nuclear fusion?

Answer 7

Combining two light (in mass) nuclei to form a heavier nuclei
-this is what powers the sun
-products are not radioactive wastes
-energy is a product

Question 8

How does the energy from nuclear reactions differ from the energy from chemical reactions?

Answer 8

1. energy released from nuclear reactions is much greater than released from chemical reactions
2. energy from nuclear reactions comes from the very small fraction of mass that is lost…the reaction converts matter into energy

Question 9

How can radioactive isotopes be used?

Answer 9

1. In medicine (tracing chemical and biological processes)
2. radioactive dating
3. industrial measurement
4. nuclear power
5. detection, treatment of disease

Question 10

Mass defect

Answer 10

-occurs in fusion AND fission
-When reactants altogether weight more than the products altogether because energy is released (mass was converted to energy)
-Calculated with E=mc^2

Question 11

Forms of spontaneous transmutation (aka natural decay)

Answer 11

Alpha and beta decay
-only have 1 reactant

Question 12

Reactants of an artificial transmutation/decay

Answer 12

-2 reactants

Question 13

What is ionizing power? Which types of radiation have the highest and lowest?

Answer 13

Radiation’s ability to damage other molecules and DNA
LOWEST: gamma
HIGHEST: alpha

Question 14

What is penetrating power? Which types of radiation have the highest and lowest?

Answer 14

-Radiation’s ability to pass through barriers
-DETERMINES ionizing power
LOWEST: alpha
HIGHEST: gamma

Question 15

What does a fusion reaction look like?

Answer 15

1. 2 reactants and 2 products

R:
1 smaller element
1 smaller element

P:
1 larger element
Energy

Question 16

What does a fission reaction look like?

Answer 16

-2 reactants and 4 products
R:
1 neutron
1 larger element

P:
1 smaller element
1 smaller element
3 more neutrons
Energy

Question 17

What are the results of gamma radiation?

Answer 17

Mass and atomic number STAY THE SAME

Question 18

What does a gamma radiation reaction look like?

Answer 18

-1 reactant and 2 products
R:
Element

P:
Same element
Photon (with no charge or mass)

Question 19

What are the results of a beta decay?

Answer 19

Beta minus: atomic number INCREASES by 1, mass STAYS THE SAME

Beta positive: atomic number DECREASES by 1, mass STAYS THE SAME

Question 20

What does a beta MINUS decay reaction look like?

Answer 20

-1 reactant and 2 products
R:
Neutron

P:
Proton
Electron/beta particle(no mass, -1 charge)

Question 21

What does a beta POSITIVE decay reaction look like?

Answer 21

-1 reactant and 2 products
R:
Proton

P:
Neutron
Positron (no mass, +1 charge)

Question 22

What does alpha decay result in?

Answer 22

Mass DECREASES by 4
Atomic number DECREASES by 2

Question 23

What does a alpha decay reaction look like?

Answer 23

-1 reactant and 2 products
R:
Element

P:
Element with mass down 4, atomic number down 2
Alpha particle (mass 4, atomic number 2)

Question 24

What is emanation?

Answer 24

The process of isotopes emitting radiation
Radioactive isotopes can emit gamma rays(photons), alpha, and beta particles