Chemistry Energy Levels

Energy Levels in Atoms

Year 11

What we will cover

• ​model the atom’s discrete energy levels, including electronic configuration and spdf notation

• investigate energy levels in atoms and ions through:

– collecting primary data from a flame test using different ionic solutions of metals (ACSCH019)

– examining spectral evidence for the Bohr model and introducing the Schrödinger model​

​What is electron configuration?

• arrangement of electrons in any given atom

• allocating electrons to the lowest possible energy level until the max number for that level is​ attained

• ​atoms want to achieve a stable electron configuration

  • noble gas configuration/full valence shell

• all elements in the same group have the same number of valence electrons

• ​transition metals often have 2 valence electrons (if not, you will be given this info)

Multiple Choice

What is the name of this element?

• Lithium

• Boron

• Carbon

• Neon

Multiple Choice

How many valence electrons?

• 2

• 3

• 5

• 10

​Orbitals - going beyond Bohr's Model

• ​Bohr's model does not explain the actual way that energy levels fill, or how all noble gases are stable even though their valence shell only fills to 8 (when it can technically fill to 18 or even 32)

• energy levels correspond to differing shapes and sizes of volumes of space - called orbitals

  • orbital = volume of space surrounding an atom in which a small number of electrons randomly move within

• orbitals can have 4 shapes (s, p, d, or f) and can hold differing numbers of electrons based on their size

​spdf orbital shapes

​How do orbitals actually work?

• There are energy levels, which increase in energy as they increase in number

• These energy levels are made up of sublevels, and these sublevels are made up of orbitals which contain the electrons

• Each orbital and sublevel can hold a particular amount of electrons

  • s = 2

  • p = 6

  • d = 10

  • f = 14

• Each orbital can only ​hold 2 electrons, but in each spdf sublevel there are different numbers of orbitals that add up to the number of electrons above

​How do we determine electron configuration?

• ​electrons always want to occupy the lowest energy orbitals

• we use a particular diagram, which lays out the sublevels and orbitals in order of energy levels

• ​this all explains why we partially fill levels in Bohr model electron configuration, because sublevels are filled and make the configuration stable

• For example, ​orbital notation for Neon:

• 1s² 2s² 2p⁶ ​

• Get used to being able to write down and remember this -->

​Orbital notation for Scandium

​spdf blocks on PT

Multiple Choice

An orbital can at most hold how many electrons?

• 1 electron

• 2 electrons

• 3 electrons

• 4 electrons

Multiple Choice

The electron configuration of an atom is 1s²2s²2p⁶.  The number of electrons in the atom is 

• 3

• 6

• 8

• 10

Multiple Choice

which of the following is the correct spdf notation of Nitrogen atom (z= 7)

• 1s² 2s² 2p²

• 1s² 2s² 2p³

• 1s² 2s² 2p⁵

Multiple Choice

What electron configuration matches an oxygen atom?

• 1s²2s²2p⁶3s2, 3p⁶4s²3d¹⁰4p⁵

• 1s²2s²2p⁴

• 1s²2s²2p⁶

• 1s²2s²2p⁶3s²3p⁶4s²3d¹

​Evidence for energy levels

1. ​If atoms are given extra energy (i.e. heated) they emit light

2. Electrons are excited and move to a higher energy level, called excited state

3. ​Electrons eventually fall back down to the normal level, called ground state

4. As they fall, excess energy is released as light (either visible, UV, or IR) ​

​

The greater amount of energy released, the shorter the wavelength, so big jumps = UV, medium = visible, small = IR ​

​

The light emitted fr​om a particular atom occurs at particular wavelengths, and has its own unique emission spectrum

​Flame Test

Heating of particular elements in a flame, they produce distinct colours

​

This is because elements have a particular electron transition that occurs more frequently than any other ​

​What spectral evidence did for the atomic model

​Bohr	Schrodinger​
​Electrons are particles orbiting the nucleus	Electrons are in a 'cloud' around the nucleus, moving at high speeds (mostly randomly) through volumes of space called orbitals ​
​Unable to explain atomic and molecular properties	​Able to explain properties of atoms, actual structure, and how they interact with other atoms
​Used mathematical equation to describe distinct energy levels	​Used mathematical equation to describe the atom as a wave, not as a particle
​Unable to explain energy levels (especially of larger atoms)	​Used emission spectrum lines to map out energy levels, from the smallest to the largest atoms

Multiple Choice

For an electron to change from ground state to an excited stated it must...

• Absorb energy

• Release energy

Multiple Choice

Line emission spectrum shown below happens when

• Electron transition from lower to higher energy level.

• Electron transition from higher to lower energy level.

• Electron exist in fixed energy states

• Electron transition between different energy levels.

Multiple Choice

Emission of light from an atom occurs when an electron

• drops from a higher to a lower energy level.

•    jumps from a lower to a higher energy level.   

•    moves within its atomic orbital.

• falls into the nucleus.

Multiple Choice

All stars are composed of a mixture of elements. When these elements are heated they emit specific amounts of electromagnetic radiation, known as an emission spectrum. Each element emits a unique, identifiable, spectrum.

Using the Bright-line emission spectrum chart below, identify the elements present in this modeled star (found in the line labeled “mixture”).

• Lithium and cadmium are in the mixture. Strontium is not in the mixture.

• Lithium and strontium are in the mixture. Cadmium is not in the mixture

• Cadmium and strontium are in the mixture. Lithium is not in the mixture

• All of the shown elements are present in the mixture.

Next lesson

• Periodicity

  • patterns/trends in the PT ​