2. When an atom gains or loses electrons they become electrically charged particles called When an atom gains or loses electrons they become electrically charged particles called Ions Ion charge on the periodic table is the ion formation

3. Lithium Atom Vs. Lithium Ion Li Lithium 3 6.9 + Lithium atom has: Lithium atom has: 3 protons, 4 neutrons and 3 electrons 3 protons, 4 neutrons and 3 electrons Lithium ion has +1 charge Lithium ion has +1 charge Loses 1 electron Loses 1 electron 3 protons, 4 neutrons and 2 electrons 3 protons, 4 neutrons and 2 electrons

5. Fluorine Atom Vs. Fluorine Ion F Fluorine 9 19.0 - Fluorine atom has: Fluorine atom has: 9 protons, 10 neutrons and 9 electrons 9 protons, 10 neutrons and 9 electrons Lithium ion has -1 charge Lithium ion has -1 charge Gains 1 electron Gains 1 electron 9 protons, 10 neutrons and 10 electrons 9 protons, 10 neutrons and 10 electrons

6. Bohr Model The first electron shell holds The first electron shell holds 2 electrons The second electron shell holds 8 electrons (Stable Octet) The third electron shell holds 8 electrons The fourth electron shell holds 18 electrons Example Potassium - K 19 protons, 19 electrons Bohr diagrams show how many electrons appear in each electron shell around an atom

7. Noble gases are very unreactive (stable) because the outer shell is full of electron Outer shell electrons are called valence electrons Other atoms gain or lose electrons in order to achieve the stability of noble gases. Gaining or losing electrons makes atoms into ions

8. Ion Formation Tendencies Metals tend to lose electrons and written: Na +1, Be 2+ Positive ions are called CATIONS Non-Metals tend to gain electrons O 2-, F 1- Negative ions are called ANIONS

9. Nitrogen atom has atomic number of 7 and atomic mass of 14 - 7 protons, 7 neutrons, and 7 electrons Nitrogen ion has 3- ion charge gains 3 electrons So Nitrogen Ion has 7 protons, 7 neutrons, and 10 electrons 7p 7 n 3- Draw the Bohr Nitrogen Ion

10. Beryllium atom has atomic number 4 and atomic mass of 9 - 4 protons, 5 neutrons, and 4 electrons Beryllium ion has 2+ ion charge loses 2 electrons So Beryllium Ion has 4 protons, 5 neutrons, and 2 electrons 4p 5n 2+ Draw the Bohr Beryllium Ion