Electronic Structure of Atoms

Continuous Line Spectrum

When light passes through a prism it splits to give a continuous spectrum

Emission Line Spectrum

Light is passed through a hot sample of gas. The emission line spectrum represents the light emitted by an atom when its electrons fall back to lower energy levels.

Absorption Line Spectrum

Light is passed through a cold sample of gas. The missing colours represent energy that entered the atom taken in by electrons.

Energy Level

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

Ground State of an Atom

One in which the electrons occupy the lowest available energy level

Excited State of an Atom

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

Neils Bohr

Suggested the lines on the emission line spectrum represent energy levels with in an atom where electron could be found revolving around the nucleus in orbits

Photon of light explanation

In its ground state, electrons occupy the lowest available energy level. The electron can move (jump/become excited) to a higher energy level if it receives a certain amount of energy. The excited state is unstable and the electron falls back to a lower level. It emits the excess energy in the form of a photon of light.

Limitations to Bohr’s theory

Bohr’s theory only worked to explain the emission spectrum of Hydrogen.Bohr’s theory did not take into account the fact that an electron had a wave motion. Did not take into account the presence of sublevels.

Sublevel

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

Atomic Orbital

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

Lyman series

When electrons fall from any energy level to the the first energy level (n=1) - ultraviolet light

Balmer series

When electrons fall from any energy level to the the second energy level (n=2) - visible light

Paschen series

When electrons fall from any energy level to the the third energy level (n=3) - infrared light

De Broglie

Stated that all moving particles move in wave motion

Heisenberg’s Uncertainty Principle

Its not possible to determine the exact position and speed of an electron at the same time only the possibility of locating an electron in a given place at any one time

Schrödinger

Developed a complex equation to calculate the location of an electron at any place at any one time. This equation revealed energy sublevels contain orbitals

Aufbau Principle

Electrons will occupy the lowest available energy sublevel

Hund’s Rule of Maximum Multiplicity

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

Pauli Exclusion Principle

No more than 2 electrons may occupy an orbital and they must have opposite spin.

Flame Tests: Sodium (Na)

Yellow

Flame Tests: Potassium (K)

Lilac

Flame Tests: Lithium (Li)

Crimson

Flame Tests: Copper (Cu)

Blue-green

Flame Tests: Barium (Ba)

Green

Flame Tests: Strontium (Sr)

Red