How to Read an Electron Configuration Chart

An electron configuration table is used to determine the number of electrons in each energy level in an atom and the arrangement of the electrons in the energy levels. The configuration table will help you determine how electrons are located around the nucleus.

The rows in an electron configuration table are made up of sets of three identifiers. The first in each set is a number, followed by a lowercase letter and then a number in superscript. The atomic number of an element tells the number of protons in one atom of the element. The number of protons will equal the number of electrons in an atom with a charge of zero. The number of superscripts will be equal to the atomic number of the element when it is written correctly.

Energy level:

The first number in the set tells you the energy level. In a series written as:

1s(2)

2s(2) 2p(3)

The highest energy level is 2.

Sublevels:

Sublevels, or orbital types, are identified by the lowercase letters s, p, d and f. Electrons will enter sublevels to in the order of their increasing energy. A sublevel must be filled or half-filled before electrons can move into the next sublevel. The s sublevel can only hold two electrons. The next sublevel p can hold six. The third sublevel, d, can hold ten electrons and the fourth sublevel, f, can hold fourteen.

Superscripts:

The superscript number tells you how many electrons are in the sublevel or orbital. S (2) tells you that there are two electrons in this s level.

Example:

Nitrogen

1s(2)

2s(2) 2p(3)

The highest energy level of nitrogen is 2. The first level has two electrons in the s shell. The second energy level has two electrons in the s and three in the p for a total of five electrons in the outer shell. The atomic number for nitrogen is 7 and as you can see from the example, nitrogen has seven electrons.

Unfortunately without the use or pictures or diagrams explaining the table is difficult. Pictures and diagrams make the learning process less complex. Practice and study is needed to fully understand an electron configuration table. The basics however are not extremely difficult and once you have a general understanding of the table it will seem less confusing and make it easier to work with. A wonderful beginners guide can be found at www.learner.org and they provide an interactive experience.

References:

http://www.learner.org/interactives/periodic/elementary4.html
http://library.thinkquest.org/10429/low/eleconfig/electron.htm
http://education.jlab.org/qa/electron_config.html