# Question aaac9

Feb 1, 2014

A noble gas notation or core notation is just a shorthand version of the electron configuration to simplify the process with larger and larger elements on the periodic table.

Let's take the example of chlorine. Chlorine has an electron configuration of

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{5}$

The noble gas one energy level (row) above chlorine is neon with an electron configuration of

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6}$

To write the noble gas configuration for chlorine we replace the electron configuration of neon $1 {s}^{2} 2 {s}^{2} 2 {p}^{6}$ with [Ne].

giving us an a noble gas (core) notation for chlorine of

$\left[N e\right] 3 {p}^{5}$

Typically, chemists do not use noble gas notation for the first 18 elements.

To illustrate a more complex configuration let's take a look at element 51 antimony (Sb).

The electron configuration is

$1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{5} 4 {s}^{2} 3 {d}^{10} 4 {p}^{6} 5 {s}^{2} 4 {d}^{10} 5 {p}^{3}$

We replace $1 {s}^{2} 2 {s}^{2} 2 {p}^{6} 3 {s}^{2} 3 {p}^{5} 4 {s}^{2} 3 {d}^{10} 4 {p}^{6}$ with the noble gas Krypton [Kr] and the noble gas notation for antimony becomes

$\left[K r\right] 5 {s}^{2} 4 {d}^{10} 5 {p}^{3}$