1. An Eye on the Ion

2. An Eye on the Ion
An atom that has either gained or lost one or more electrons resulting in a net electrical charge (positive or negative).

3. An Eye on the Ion Sodium – Na How many protons? 11 How many electrons?
Draw the electron orbitals.
2, 8, 1
How many electrons are in the outer energy level? 1

4. An Eye on the Ion
Rather than draw all of the orbitals, it is sometimes helpful to draw the electrons in the outer energy level only. You do this by drawing the symbol and adding dots to represent the electrons.
This is called the electron dot structure or Lewis Dot Structure.

5. An Eye on the Ion
Draw the electron dot structure for sodium.

6. An Eye on the Ion
For an atom to be stable, it needs to have its outer energy level full of electrons (like Noble Gases).
What is the best way to make a sodium atom stable?
It gives away an electron
When sodium loses an electron it becomes positively charged. We also say that it has a valence charge of +1.
A positively charged atom is called a _____.
Cation

7. An Eye on the Ion
The symbol we use for ions is the atom’s symbol with the charge in the upper right hand corner.
Na+1

8. An Eye on the Ion Chlorine – Cl How many protons? 17
How many electrons?
Draw the electron orbitals.
2, 8, 7
How many electrons are in the outer energy level? 7

9. An Eye on the Ion
Draw the electron dot structure for chlorine.

10. An Eye on the Ion What is the best way to make a chlorine atom stable?
It takes an electron
When chlorine gains an electron it becomes negatively charged. We also say that it has a valence charge of -1.
A negatively charged atom is called a _____.
Anion

11. The symbol for a chlorine ion is Cl-
An Eye on the Ion
The symbol for a chlorine ion is Cl-

12. An Eye on the Ion
When an atom GAINS electrons it becomes NEGATIVELY charged.
When an atom LOSES electrons it becomes POSITIVELY charged.

13. An Eye on the Ion
Elements toward the LEFT of the Periodic Table tend to LOSE electrons to form + ions (cations).
Elements toward the RIGHT of the Periodic Table tend to GAIN electrons to form – ions (anions).

14. An Eye on the Ion
How can sodium and chlorine work together to become stable?  +
Ionic compound – sodium chloride