Electron Orbitals & Spectroscopy

Worksheet

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Spectroscopy Questions

Explain what is meant by the idea that energy of electrons in atoms is quantized.

Answer

This is the idea that electrons can only have specific amounts of energy, which in the case of electrons in atoms means that they can only occupy specific orbitals.

Photoelectron spectroscopy is used to determine the energy of electrons in an atom.

a) What is the atom irradiated with?

Light, usual UV light.

b) What is the relationship between the energy applied to the atom and the energy of the electron released from the atom?

The energy of the light is given by E=hf where h is Planck constant and f is the frequency of the light. The difference between the energy of the light hitting the atom and the light re-emitted is the ionisation energy of the atom.

c) Write the symbol equation for the reaction that occurs when an atom of magnesium undergoes photoelectron spectroscopy.

Mg_(g) → Mg⁺_(g) + e^–

The emission spectrum when hydrogen is excited using high energy electrons is shown below.

a) Explain why the hydrogen atom can only emit light of certain frequencies.

Electrons can only exist in certain specific energies according the orbital they occupy. Light is emitted as electrons fall from a higher energy orbital to a lower energy one. Specific energy levels must be specific gaps between these levels, resulting in specific wavelengths being emitted.

b) Explain why the hydrogen atom can emit more than one frequency of light.

Although hydrogen normally only have 1 electron (as an atom), when it is excited, the electron can be found in one of multiple orbitals that exit.

Electron Shell Questions

The first orbital in every shell is called the S-orbital.

a) What is the shape of an s-orbital and how many s-orbitals are there in each shell?

Spherical, 1

b) Sketch a plot demonstrating the probability of finding a 1s electron at different distances from the nucleus.

Graph of probability vs distance for 1s electron

c) In words, explain the shape of the graph.

The probability of finding an electron at any given distance from the nucleus is dependent on the wavefunction and the volume of the shell at that distance.

P-orbitals can be found in the second shell onwards.

a) Sketch the shape of a p-orbital and state how many there are in each shell?

Figure of 8, 3 of them

D-orbitals can be found in the 3rd shell onwards.

a) Sketch the shape of all the possible d-orbitals and state the number of d-orbitals in each shell.

b) Sketch a diagram showing the energy of all of the orbitals in a caesium atom.