Energy levels are defined as the fixed energy value that an electron in an atom may have.
Inside an atom, the electron may only occupy certain positions with a very definite radius from the nucleus. These locations are known as energy levels/orbits/shells. An electron occupying one of these energy levels can only possess specific amounts of energy.
If a number (n) is assigned to each energy level, the number of electrons it can hold is given by the formula: electron capacity=2n².
Energy level number Electron capacity
1 2(1²) = 2
2 2(2²) = 8
3 2(3²) = 18
Some levels are made up of sub-levels, and are denoted by the letters s, p and d. The d sub-level holds 10 electrons. The p sublevel holds 6 electrons. The s sublevel holds 2 electrons.
The s sublevel is the lowest of the sublevels and as the levels increase, energy increases.
The number of sublevels in a main sublevel is the same as the number of that level e.g. the n=3 main energy level has 3 sublevels.
The electron has properties normally associated with waves e.g. it can be shown to have a wave length, i.e. it doesn’t travel in a fixed path at a definite distance from the nucleus. This is known as the wave nature of the electron. To determine the location or velocity of an electron in an atom it is illuminated with radiation. The reflected radiation should give information about the electron. But radiation interferes with the electron by changing the position and/or momentum of electron. Reflected radiation gives false information.
The Heisenberg Uncertainty Principle states that it is impossible to measure at the same time both the velocity and position of an electron.
An orbital is a region in space in which there is a high probability of finding an electron. S orbitals are spherical while p orbitals are dumbbell shaped.
There are three p orbitals in a p sublevel, px, py, pz and they are arranged at right angles to each other along the x, y and z axes.
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