Topic 2.3: Electronic Arrangement

2.3.1 Describe the electromagnetic spectrum

Electromagnetic radiation comes in different forms of differing energy. Gamma rays are a particularly high energy form and the visible light we need to see the world is a lower energy form. All electromagnetic waves travel at the same speed and can be distinguished by their different wavelength.

This is the full electromagnetic spectrum

Note: They are all called light, it depends whether we can see it or not. Hence a section is called the visible light.

2.3.2 Distinguish between the continuous spectrum and line spectrum

White light is a mixture of light waves of differing wavelengths or colors. We see this when sunlight passes through a prism to produce a continuous spectrum.

Line spectrum shows some colors of the continuous spectrum, this is because it is an emission spectrum.

The colors present in the emission spectrum are the same as those that are missing from the absorption spectra. As different elements have different line spectra they can be used like bar-codes to identify unknown elements.

2.3.3 Explain how the lines in the emission spectrum of hydrogen are related to electron energy levels.

Excite atoms using heat can give off pretty light. It excites the electron to a higher energy shell, but these lights are actually made up of a electrons releasing energy when they jump back to the lower energy shell.

The hydrogen atom gives out energy when an electron falls from a higher to lower energy level. Hydrogen produces visible light when the electron falls to the second energy level (n=2). The transition to the first energy level correspond to a higher energy change and are in the ultraviolet region of the spectrum. Infrared radiation is produced when an electron falls to the third or higher energy.

http://www.youtube.com/watch?v=6rHerkru60E is a good video that explains the electron energy levels.

The lines converge at higher energies because the energy levels inside the atoms are closer together. When an electron is at the highest energy (n = infinity), then the atom has been ionized.

Most notable discovery is that the line spectra is exactly the same as the energy levels.

2.3.4 Deduce the electron arrangement for atoms and ions up to Z = 20

Atoms

Hydrogen - 1
Helium - 2
Lithium - 2, 1
Beryllium - 2, 2
Boron - 2, 3
Carbon - 2, 4
Nitrogen - 2, 5
Oxygen - 2, 6
Fluorine - 2, 7
Neon - 2, 8
Sodium - 2, 8, 1
Magnesium - 2, 8, 2
Aluminium - 2, 8, 3
Silicon -2, 8, 4
Phosphorous - 2, 8, 5
Sulfur - 2, 8, 6
Chlorine - 2, 8, 7
Argon - 2, 8, 8
Potassium - 2, 8, 8, 1
Calcium - 2, 8, 8, 2

The general rule of thumb is that first shell has a maximum of 2, second shell has a maximum of 8 and third shell has a maximum of 8.

Ions

Hydrogen - 0
Helium - 2
Lithium - 2
Beryllium - 2
Boron - 2
Carbon - 2, 8
Nitrogen - 2, 8
Oxygen - 2, 8
Fluorine - 2, 8
Neon - 2, 8
Sodium - 2, 8
Magnesium - 2, 8
Aluminium - 2, 8
Silicon -2, 8, 8
Phosphorous - 2, 8, 8
Sulfur - 2, 8, 8
Chlorine - 2, 8, 8
Argon - 2, 8, 8
Potassium - 2, 8, 8
Calcium - 2, 8, 8

General rule of thumb, when it is an atom becomes an ion. It wants a full outer electron shell.