Atomic Structure – Definitions and Laws

Definitions and Laws

Like most of the topics, it is essential to know the language of the topic, i.e., the relevant definitions and laws. The following are those that pertain to atomic structure:

Atomic number
The atomic number corresponds to the number of protons in the nucleus of an atom of that element. It also corresponds to the number of electrons in the neutral atom.

Mass number
The number of protons and neutrons in an atom of the element.

Atoms of the same element but which differ in the numbers of neutrons in their nuclei (or, have different mass numbers).

Noble gas
One of the elements of Group 0 of the Periodic Table

Transition element
One whose atoms have an incomplete d orbital.

Energy level
A measure of the amount of energy possessed by an electron when it is in an atom.

Ground state
The state of an atom when all of its electrons are in their lowest available energy levels.

Excited state
The state of an atom when one or more of its electrons have been promoted to higher energy levels.

Principle quantum number
A number that indicates the main energy level, or shell number, of an electron in an atom.

The region in space around the nucleus of an atom in which the electrons are most likely to be found.

Aufbau principle
Electrons occupy the lowest available energy level.

Ionisation energy
The first ionisation energy of an element is the minimum energy required to completely remove the most loosely-bound electron from an isolated atom of the element.

Atomic Structure Study Cards

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