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Lesson 2.6   Electron Configuration Diagrams              Oct. 6


Each Element has a certain number of electrons, protons and neutrons.

This information can be found on your PERIODIC TABLE.


Symbol                    Capital + ?               Cl = chlorine



Atomic Number        Whole number         17 = number of protons

                                                                     = number of electrons

                                                                           ( if it is neutral atom)

                                                           * if they lose or gain electrons they become charged ions.



Atomic Mass  ………..A decimal that represents the average of the  element with different mass, made up of protons and different numbers of neutrons (isotopes.)  To find the most abundant element round the decimal to a whole number.

Cl = 35.5  →  36

…means that chlorine has a total of 36 protons and neutrons.


To get neutrons, just subtract the atomic number (17 protons) from 36 = 19 neutrons.







ELECTRONS          So, to count the electrons in an element just get the number of protons which was the Atomic Number.


These electrons fill up basic levels,

Level 1 can hold 2 e-

Level 2 can hold 8 e-

Level 3 can hold 8 e-

Level 4 can hold 18 e-

Level 5 can hold 18 e-


Practice         - Try page 5 on the booklet.

                     - complete table, answer questions 1-5


Note – VALENCE means the number of electrons in the outermost energy level


Friday – Do pages 6-8, if no school.