What is the principal quantum number?
The number given to each energy level an electron can occupy, with n = 1 representing the electron's lowest possible energy - ground state.
What does an electron have to do to move down an energy level?
Electrons can move down an energy level by emitting a photon.
What is an electron-volt?
An electron-volt is the kinetic energy carried by an electron after it has been accelerated through a potential difference of 1 volt.
1eV is equivalent to how many Joules?
1eV = 1.6 x 10-19
Why are all the electron energies negative?
They are negative because of where the zero energy is defined.
What happens to the energy value of the electron as it moves to a higher energy level, and when is the electron no longer bound to the atom?
The higher the energy level, the more energy the electron has and the less negative the energy. An electron is 'free' and no longer bound to the atom when it has a potential energy of zero - the atom becomes ionised.
Explain how the energy carried by a photon released from an electron changing energy states can be calculated.
The energy carried by each photon is equal to the difference in energies between the two levels.
E = E1 - E2 = hf = hc/ ¥
What is the Pauli exclusion principle?
It states that no two fermions can be in exactly the same quantum state at the same time. In the contect of energy levels, that means no more than two electrons can be in the same energy level at the same time.
Why do you get a line absorption spectrum when light with a continous spectrum passes through a cool gas?
At low temperatures, most of the electrons in the gas atoms will be at their ground states. Photons of the correct wavelength are absorbed by the electrons to excite them to higher energy levels.
These wavelength are then missing from the continous spectrum when it comes out the other side of the gas.
Explain how an emission spectra is formed.
When a gas is heated up electrons go up the energy levels. When an electron falls into a lower energy level , it emits a photon. Emission spectra show the wavelengths of photons emitted. They are made up of a series bright lines corresponding to the wavelengths emitted.
How did de Broglie suggest that the electrons travel around the nucleus?
Since light has both particle and wave characteristics, de Broglie suggested that electrons should have a wave like character.
Specifically, when the electrons orbit around a nucleus they ought to behave like the standing waves that are formed on a guitar when it's plucked.
What does the principal quantum number of electrons affect the waves that surround the atoms nucleus.
The principal quantum number is equal to the number of complete waves that fit the circumference.
The wavelength of the electron waves should fit the circumference of the orbit a whole number of times.
Write out the Erwin Schrodinger equation that calculates the energy levels in a hydrogen atom.
En = -13.6e/n2