Lesson 5 (Nuclear Stability)

Nuclear chemistry

is the study of reactions involving changes in atomic nuclei or the dense region consisting of protons and neutrons at the center of an atom.

Atomic number (Z)

the number of protons in the nucleus is called the ___________ of the element,

Mass Number (A)

Sum of the number of protons and the number of neutrons is____

Nuclide

is a single type of nucleus and it is identified by the notation A/Z X

Isotopes

Atoms with the same atomic number but different mass numbers are ____ of the same element.

Repel

From Coulomb’s law we know that like charges ______

Attract

From Coulomb’s law unlike charges ____ one another.

Repulsion > attraction

The nucleus disintegrates, emitting particles and/or radiation.

Attractive forces prevail.

The nucleus is table if,

It is stable

If n/p is close to 1, low atomic number then,

Atomic number np is greater than 1

This means that a larger number of neutrons is needed to counteract the strong repulsion among the protons and stabilize the nucleus.

A nuclear is stable if

It cannot be transformed into another configuration without adding energy from the outside. Of the thousands of nuclides that exist, about 250 are stable.

Magic numbers

Nuclei with certain numbers of nucleons are stable against nuclear decay.

What are the magic numbers? These numbers of protons or neutrons ____ make complete shells in the nucleus.

(2, 8, 20, 28, 50, 82, 126)

Double magic

Nuclei that have magic numbers of both protons and neutrons are called ____ and are particularly stable.

They are generally more stable,

Nuclei with even numbers of both protons and neutrons are generally more stable than those with odd numbers of these particles.

Radioactive

All elements having an atomic number greater than 83

Unstable and exhibit radioactivity.

The nuclei that are to the left or right of the band of stability are,

Protons and neutrons

are the constituents of the atomic nuclei.

Alpha particles

are high-energy helium nuclei.

Beta particles

are high-energy electrons

Positrons

are positively charged electrons (“anti-electrons”).

Balanced nuclear equation

indicates that there is a rearrangement during a nuclear reaction in the nucleons (subatomic particles within the atoms’ nuclei) rather than atoms.

Conservation of Mass number

The sum of the mass numbers of the reactants equals the sum of the mass numbers of the products.

Conservation of Atomic number

The sum of the charges of the reactants equals the sum of the charges of the products