Electron Shells

Question 1

Electron shells (also known as ‘Energy Levels’) each hold a specific number of electrons. What is the formula used to calculate the MAX number of electrons any one shell can contain?

Answer 1

2n^2 (2 x n squared) where ‘n’ is the energy level.

e.g. The fifth (5) energy level from the nucleus would be able to fit up to 2 x 5^2 electrons, or 50 electrons.

Question 2

The ‘Valency’ of an atom is the number of Valence electrons it has. What is the Valency of Tin(Sn)?

Answer 2

Tin has a valency of 4, since it has 4 Valence electrons.

Question 3

One method of representing the Valency of an Atom is using a ‘Lewis Dot Diagram’. Create a Lewis Dot Diagram Representing Beryllium(Be) and Sulfur(S):

Answer 3

. ..
Be - - S - -
.

These diagrams show an element’s symbol, with dots above, below, and to the left and right of it representing its’ valence electrons. Place the first dot above the symbol and place the rest around it in a clockwise direction. An element with 4 valence electrons would have 4 dots, one on each side of the symbol.

Question 4

Bohr Diagrams show a central nucleus surrounded by each electron shell, with electons’ positions marked. Create a Bohr diagram of a Lithium atom:

Answer 4

. ___ . ___
/ . \
| (•) . |
\ ________ /

Lithium has 3 electrons, with two in the first shell and 1 in the second. Here ‘•’ represents the nucleus.