N-Z Graphs

Question 1

Stability graph axis

Answer 1

Atomic/proton number Z on the x axis

Neutron number, N on the y axis

Question 2

A nucleus will be unstable if it has

Answer 2

too many neutrons
too few neutrons
too many nucleons/too heavy
too much energy

Question 3

Stable nuclei are located where on the graph

Answer 3

they lie along a belt curving upwards with an increasing neutron-proton ratio (to dilute the increasing electrostatic repulsive force) from the origin to approximately (80, 120)

Question 4

Neutron-proton ratio for beta minus and beta plus emitters

Answer 4

- = high
\+ = low

Question 5

Why dose the number of neutrons increase at a faster rate than the number of protons for stable nuclei

Answer 5

to dilute the electrostatic force caused by an increase in protons
The extra neutrons help to bind the nucleons together without introducing repulsive electrostatic forces as more protons would do

Question 6

There are no alpha emitters for what values of Z

Answer 6

Z < 60 roughly

Question 7

Unstable nuclei occur at what proton numbers

Answer 7

p > 84

Question 8

The largest stable nuclei is

Answer 8

Bi-209

Question 9

Most alpha emitting nuclides are larger than Bi-209 and therefore lie
Those smaller than Bi-209 lie

Answer 9

above the top of the stability belt of the N-Z plot

below the N-z stability belt

Question 10

For light isotopes (0 < Z < 20), the stable nuclei follow

As Z increases beyond about 20, stable nuclei are

Answer 10

the straight line N=Z so the proton number is constant while the neutron number increases.

neutron-rich as more neutrons than protons