PS-2.5 Predict the charge that a representative element will acquire according to the arrangement of electrons in its outer energy level.

Key Concepts:  ion 

    By definition, an ion is an electrically charged atom or group of atoms. Ions that carry a positive charge are called cations, and atoms that carry a negative charge are referred to as anions. In the ground state ( lowest energy state,) atoms have the same number of electrons as protons. This equality of + and - charge mean that under natural conditions, atoms are electrically neutral. However, if an atom does not have the same number of electrons as protons, then the atom will carry a + or - electrical charge, and it will be an ion. Under certain conditions atoms can gain or lose valence electrons to become either a negative or positive ion. If an atom gains valence electrons it will be a negatively charged ion, or anion, because it will have more -Electrons than +Protons. If an atom loses valence electrons it will become a positively charged ion, or cation, because it will have fewer -Electrons than +Protons. Even though atoms can become electrically charged, they are still atoms of the same element. A Lithium atom with a net charge of +1 is still a Lithium atom. A Fluorine atom with a net charge -1 is still an atom of the element Fluorine.

                                                  
A Boron atom becomes a 3+ cation.                           A Fluorine atom becomes a 1- anion.

The chart below shows common electrical trends on the periodic table.       

ELECTRON TRENDS

GROUP

ELECTRON TENDENCY AND ION CHARGE

GROUP NAME

OXIDATION #

ELECTRON DOT DIAGRAM

GROUP 1 

Atoms lose 1 valence electron to become 1+ ions 

Alkali Metals

1+

 

GROUP 2 

Atoms lose 2 valence electrons to become 2+ ions

Alkali Earth Metals

2+

 

The Transition Metals in groups 3 through 12 are not shown here.
Most can lose 1,2,or 3 valence electrons to become 1+, 2+, or 3+ ions respectively.

GROUP 13 

Atoms lose 3 valence electrons to become 3+ ions

Boron Group

3+

 

GROUP 14 

Atoms can lose or gain 4 valence electrons to become 4+ or 4-ions

Carbon Group

4+ OR 4-

 

GROUP 15  

Atoms gain 3 valence electrons to become 3- ions

Nitrogen Group

3-

 

GROUP 16   

Atoms gain 2 valence electrons to become 2- ions

Oxygen Group

2-

 

GROUP 17   

Atoms gain 1 valence electron to become 1- ions

Halogens

1-

 

GROUP 18   

Atoms are stable with 8 valence electrons...Except for Helium. It is stable with a filled first level containing 2 valence electrons. These elements are stable. Their valence level is filled.

Noble Gases

0

 

  Watch the video lesson on electron configurations:     Part 1   part 2    part 3