Mini-summary moment:

Lesson moment:

Let's review on last lesson. We deducted that the nuclear strong force that is created from energy released when an atom is made exceeds the repulsion force of protons, and this is how nucleons (protons and neutrons) can stay together.

As referenced in the title, we will be mainly concerned with stability of the nucleus during this lesson.

We can determine the stability of a nucleus if we know the amount of protons and neutrons inside of it. What we do with these amounts is that we find a ratio of neutrons (N) to protons (Z). Let's go back to the example of the lithium atom.

N/Z = 3/3

   = 1

The neutron to proton ratio is 3:3 or 1, which signifies a stable nature. This only applies to elements from hydrogen to calcium (1-20) as stability gets more complicated after that point so we’ll talk about that more later. Now let’s look at another example, carbon-14 (isotope of carbon with 8 neutrons)

N/Z = 8/6

   = 1.333

We get a ratio that is greater than 1, which signifies an unstable nature (again, of course, only elements 1-20). This means that the substance, no matter how much its N:Z ratio differs from 1, will constantly undergo radioactive decay. It decays as it desires to have the most stable nuclei possible, which normally happens with isotopes of elements but also happens with isotopes we see in the periodic table (generally far ahead of calcium so we’ll get into that later).

Let’s now take a look at an equation which describes this decay (drawing as equations in notion are bad for some reason):