Question

1. what is an electron?
2. how many electrons can be held in the:

1st shell: 2
2nd shell: 8
3rd shell: 16

Explanation:

An electron is a sub - atomic particle with a negative charge. It is one of the fundamental particles that make up an atom. The number of electrons in each shell is determined by the formula \(2n^{2}\), where \(n\) is the shell number. For the 1st shell (\(n = 1\)), \(2\times1^{2}=2\); for the 2nd shell (\(n = 2\)), \(2\times2^{2}=8\); for the 3rd shell (\(n = 3\)), \(2\times3^{2}=18\) (it should be noted that in some cases, when considering the filling order and stability, the 3rd shell can hold 8 electrons before the 4th shell starts to fill in some simple models for basic understanding).

Answer:

1. An electron is a negatively - charged sub - atomic particle.
2. 1st shell: 2; 2nd shell: 8; 3rd shell: 18.