Chapter 3.2-4.10: Arrangement of Electrons in the Atom & Trends in the Periodic Table

Energy level

The fixed energy value that an electron in an atom may have

Ground state of an atom

When electrons occupy the lowest available energy levels

Excited state of an atom

When electrons occupy higher energy levels than those available in the ground state

Heisenberg's Uncertainty Principle

It is impossible to measure at the same time both the velocity and position of an electron

Hund’s Rule

when two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs

The Pauli Exclusion Principle

no more than two electrons may occupy an orbital and they must have opposite spins

Aufbau Principle

Electrons will occupy the lowest available energy level first.

first ionisation energy

the minimum amount of energy required to remove an electron from the outermost energy level

second ionisation energy

the energy required to remove the most loosely bound electron from each singly charged positive ion in a mole

An orbital

A region in space within which there is a high probability of finding an electron

A sublevel

A subdivision of a main energy level that consists of one or more orbitals of the same energy

an element

A substance that cannot be broken down into simpler substances by chemical means

electron configuration

the arrangement of electrons in an atom of that element

atomic radius

half the distance between the nuclei of two atoms that are joined together by a single covalent bond

electronegativity