electron orbitals

Rutherford’s atom consists of a tiny, dense nucleus at the center and electrons that occupy most of the volume of the atom.

The hydrogen atom can emit only certain energies as it changes
from a higher to a lower energy.

Hydrogen has quantized energy levels

The Bohr model assumed electrons travel around the nucleus in circular orbits, which is incorrect.

The wave mechanical model assumes the electron has both particle and wave properties and describes electrons as occupying orbitals.

• The orbitals are different from the Bohr orbits.

• Probability maps indicate the likelihood of finding the electron at a given point in space.

• The size of an atom can be described by a surface that contains 90% of the total electron probability.

Atomic energy levels are broken down into principal levels (n), which contain various numbers of sublevels.

• The sublevels represent various types of orbitals (s, p, d, f),
  which have different shapes.

• The number of sublevels increases as n increases.

A given atom has Z protons in its nucleus and Z electrons surrounding the nucleus.

The electrons occupy atomic orbitals starting with the lowest energy (the orbital closest to the nucleus).

The Pauli exclusion principle states that an orbital can hold only two electrons with opposite spins.

The electrons in the highest energy level are called valence electrons.

The electron arrangement for a given atom explains its position on the periodic table.

Atomic size generally increases down a group of the periodic table and decreases across a period.

Ionization energy generally decreases down a group and increases across a period.