SAS 4: Quantum Numbers and Electronic Configuration

Electron Shell

A region of space around the nucleus where electrons are most likely found.

Electron Subshell

A region of space within an electron shell that contains electrons that have the same energy.

Orbitals

Electron subshells have within them a certain, definite number of locations (regions of space), called?

Orbitals

Is a region of space within an electron subshell where an electron with a specific energy is most likely to be found.

2

An electron orbital can accommodate a maximum of _____ electrons.

Electron Spin

Experimental studies indicate that as an electron “moves about” within an orbital, it spins on its own axis in either a clockwise or a counterclockwise direction.

Quantum Numbers

Are used to determine the electron configuration of an atom and the probable location of the atom's electrons.

Quantum Numbers

Used to understand other characteristics of atoms, such as ionization energy and the atomic radius.

Principal Quantum Number

It is the main energy level.

Principal Quantum Number

Related to the average distance from the nucleus.

Principal Quantum

Should be an integer, it can’t be zero.

2n²

The number of electrons per energy level can be computed using the formula:

Azimuthal Quantum Number

It is responsible for the shape of the electron cloud.

Spherical

Name of 0 Azimuthal = S Subshell.

Dumbbell-shaped

Name of 1 Azimuthal = P Subshell.

Cloverleaf-shaped

Name of 2 Azimuthal = D Subshell.

Complex

Name of 3 Azimuthal = F Subshell.

Magnetic Quantum Number

It is responsible for the ORIENTATION of electron cloud.

Magnetic Quantum Number

This identifies the ORBITAL in an atom.

Spin Quantum Number

It is responsible for the DIRECTION of the electron cloud.

Pauli’s Exclusion Principle

No two electrons can have the same set of quantum numbers.

Aufbau’s Principle

Building Principle

Aufbau’s Principle

Lower electron orbitals are filled first.

Hund’s Rule of Pairing

Orbitals are filled up singly before pairing.

Heisenberg’s Uncertainty Principle

It is impossible to determine simultaneously the momentum and position of an electron.

Electron Configuration

A statement of how many electrons an atom has in each of its electron subshells.

Electron Configuration

Indicate how many electrons of various energies an atom has.

Valence Electrons

Is an electron that is the most likely to be involved in a chemical reaction.

Valence Electrons

They are typically the electrons with the highest value of the principal quantum number, n.

Valence Electrons

Can be found by determining the electronic configurations of elements. Thereafter the number of electrons in the outermost shell gives the total number of valence electrons in that element.