Test 2!

Question 1

Describe the physical manifestation that indicates that an atom possesses an unstable nucleus.

Answer 1

radiation

Question 2

Explain the meaning of the term “radioactivity”

Answer 2

emission of radiation from an unstable atom

Question 3

Explain the limit for nuclear stability in terms of the number of nucleons present in an atomic nucleus

Answer 3

over 209 nucleons

Question 4

Explain the relationship between nuclear stability and neutron to proton ratio for elements of low atomic number

Answer 4

more neutrons than protons- stronger nuclear force

Question 5

Explain the relationship between nuclear stability and neutron to proton ratio for elements of high atomic number

Answer 5

less neutrons than protons causes more repulsion between protons

Question 6

Explain the meaning of the term “half-life” as it relates to nuclear stability

Answer 6

the time it takes for 1/2 of a radioactive substance to decay
stable- longer half- life
unstable- shorter

Question 7

Half-life

Answer 7

initial amount x (1/2)^ time/ # of half-lives

Question 8

Positron emission

Answer 8

proton is converted into a neutron and positron, positron is emitted

Question 9

Electron capture

Answer 9

electron is pulled into the nucleus, converting proton into neutron

Question 10

Beta decay is used when

Answer 10

there are too many neutrons

Question 11

Electron capture is used when

Answer 11

there are too many protons

Question 12

Radioactive decay series

Answer 12

series of reactions beginning with unstable atom and going to unstable atom