Name ___________________________________ Date ____________
Period___
Electron Configurations: Noble Gas Notation
Directions: Answer the following questions. Make sure to read everything when it says READ THIS.
1. Write the electron configuration for neon.
2. Write the electron configuration for sodium.
3. Write the electron configuration for magnesium.
4. Circle the parts of the electron configurations that neon, sodium, and magnesium have in
common.
READ THIS: Electron configurations are quick to write for the 1s, 2s, and 2p orbitals. As you have seen in
your homework, it takes a while and it is very tedious to write electron configurations for 3s, 3p, 4s, 3d,
4p… orbitals. Chemists want to take less time writing electron configurations, so instead of writing the
full electron configuration for atoms with many electrons, they use shorthand notation. That shorthand
notation is called the noble gas notation. What you did in number 4 is almost like what chemists did
when developing the noble gas notation.
5. Does neon come before or after sodium and magnesium on the periodic table?
6. A. Write the symbol for neon in brackets
B. In the same line where you wrote neon’s symbol in brackets, write the rest of the electron
configuration for sodium (what you have not circled).
READ THIS: By answering questions 5 and 6, you just wrote a noble gas notation. In a noble gas
notation, the noble gas that comes before the desired element on the periodic table is written in
brackets. Then the rest of the electron configuration is written after the noble gas that is in the brackets.
Here is an example for cobalt.
Noble gas
[Ar]4s23d7
Energy level
Number of electrons
Sublevel
7. Write the noble gas notation for calcium.
8. Write the noble gas notation for bromine.
9. Write the noble gas notation for mercury.
10. Write the noble gas notation for uranium.