Electron configuration

Question 1

What formula is used to show how many electrons can fit into a main energy level?

Answer 1

2n^2
n: the main energy level
the result is the number of electrons that fit into it

Question 2

What are the principal energy levels and the principal quantum number? Explain which shells have most energy and which ones are furthest away.

Answer 2

They are the main energy levels. They are assigned numbers (n) when n=1 is closest to the nucleus and lowest in energy. The distance between each sublevel decrease, the further away they are from the nucleus and the energy levels increase in energy.

Question 3

What are the sub-levels in which the main energy levels are divided into?

Answer 3

Sub-levels: s, p, d or f

The sub-levels increase in energy. E.g. the f sub-level has more energy than the d sub-levels

Question 4

What is an atomic orbital?

Answer 4

A region of space where there is a high probability of finding an electron. One box is an orbital which can contain a maximum of 2 electrons.

Question 5

What are the shapes of the s and p sub-levels?

Answer 5

• The s sub-levels have 1 orbital as they can fit in a maximum of 2 electrons. The ‘s’ atomic orbitals are spherical (have a x, y and z axis)
• The p sub-level contains 3 orbitals (they are right-angled) the orbitals are called Px, Py and Pz
  and are dumbbell shaped.
• Each one of these p-orbitals, lie on their according axis. Px lies on the x axis, same applies to the others.

Question 6

Explain the different energy states of the orbitals and the degenerate orbitals.

Answer 6

• Accodring to the aufbau principal, the electons fill atomic orbitals of lowest energy first. 1s sub-level has the lowest and hence fills first.
• However the atmoic orbiatls within a sub-level are of equal energy (degenerate orbitals) e.g. 2p, 3p and 4p are of equal energy
• Remember the 4s sub-level is below the 3d sub-level and therefore fills before

Question 7

What is the Pauli exculsion principal and the Heisenberg’s uncertainty principal?

Answer 7

• Two electrons can only occupy the same atomic orbital if they have opposite spin which are shown as arrows. One rotates clockwise the other anti-clockwise.
• There is a 95% chance that an electrons will be found in an atomic orbital

Question 8

What does the Hund’s rule state?

Answer 8

Each orbital first fills with one electron and then doubled.

Question 9

Be able to draw the image of the aufbau principal, the increasing energy of the orbitals and list the electron configuration in the right order.

Question 10

Explain the numbers in the electron configuration.

Answer 10

1s^2
The fist one is the quantum number (main energy level) and the small number (to the power of s) is the number of electrons in sub-levels.

Question 11

Give an example and exlain the condensed electron configuration.

Answer 11

First the noble gas notation (the gas that is closest) is written down in brackets and the rest of the configuration follows.

Question 12

Explain the two exceptions in the electron configuration of Cr and Cu.

Answer 12

For both of them the 4s sub-level only contains one electron 4s^1 instead of two electrons 4s^2. In these exceptions the 4s and 3d are on the same energy level. Normally the 4s is under the 3d.

Question 13

Explain the electron configuration in ions.

Answer 13

Because the 4s sub-level is lower in energy than the 3d sub-level, the electrons are first removed from the 4s.
For anions, the number of electrons increases
For cations, the number of electrons decreases

Question 14

What is the electromagnetic spectrum, name the 7 EM radiations that exist and on what basis can they be classified?

Answer 14

The range of all possible frequencies of electromagnetic radiation. These include: radio waves, microwaves, infrared, visible light, ultraviolet light, x-rays and gamma rays
These electromagnetic radiations can be classified and distinguished based on their energy, wavelength and frequency

Question 15

What is the wavelength, frequency and energy in the electromagnetic spectrum?

Answer 15

Wavelength: the distance between two maximum points in an oscillating curve (metres)
Frequency: the number of waves that pass a point in one second (hertz)
Energy: of the electromagnetic radiation depends on its frequency (joules)

Question 16

What is the relationship between colour, frequency, wavelength and energy across the electromagnetic spectrum?

Answer 16

• Frequency and wavelength inversely proportional
• Frequency x wavelength = speed of light (or a constant)
• Higher energy = higher frequency = shorter wavelength
• Lower energy = lower frequency = longer wavelength
• Energy increases from right to left on the EM spectrum

Question 17

What is the order from lowest energy to highest energy in the EM spectrum?

Answer 17

lowest
- infrared radiation
- visible light
- ultraviolet light
highest

Question 18

What is the difference between a continuous spectrum and a line spectrum?

Answer 18

The line spectrum links to the emission line spectrum (dark background) which only contains certain frequencies/wavelengths of light present

The continuous spectrum shows all frequencies/wavelengths of light present. This is only produced when white light passes through a prism

Question 19

Explain how emission spectra are produced.

Answer 19

When a high voltage is passed through a gas, the electrons become excited and transition to higher energy levels. When the electrons return to a lower energy level (fall back down), an emission spectra is produced when energy is emitted in the form of photons (light particles). Colourful lines on a black background.

Question 20

In a hydrogen emission spectrum, at which energy shells are what type of EM radiations produced?

Answer 20

The extend to where the electrons are promoted to, depends on the amount of energy absorbed.
When the electrons transition down to the n=1 energy level, the energy emitted corresponds to the wavelength and frequency of UV radiation
n=2 corresponds to visible light
n=3 corresponds to infrared radiation
The longer the arrow, the greater amount of energy is emitted
Electrons can only transition to main energy levels
The line emission spectrum shows that electrons are arranged in separate energy levels

Question 21

How are absorption line spectra produced?

Answer 21

When electrons absorb energy and transition to higher energy levels.

Question 22

What colors of light are produced when energy is emitted from n=3 to n=2?

Answer 22

Visible light because of the n=2 and the colour red is produced as it has low energy

Question 23

What is the convergence limit and when is it reached?

Answer 23

At a certain point, the convergence limit is reached, the electrons beyond that point are free from the influence of the nucleus.

Question 24

What is quantized energy?

Answer 24

Electrons of a certain atom can only possess personalized or specific energy values due to the amount of energy absorbed and emitted.