2. Vocabulary ATOM-the smallest unit that maintains the characteristics of an element – Nucleus- The center of the atom, contains protons and neutrons – Electron Cloud –Region surrounding the nucleus containing the electrons

3. The Atom

4. Nucleus Protons Neutrons

5. The Nucleus The number of protons is the same as the atomic number Li 3 7 The atomic mass The Atomic Symbol

6. The Nucleus Neutrons = atomic mass – atomic number Li 3 7 The atomic number The atomic mass

7. Li 3 7 The atomic number The atomic mass 7 (Atomic Mass) -3 protons(Atomic #) 4 neutrons

8. Review How many protons does Mg have? How many neutrons does Mg Have?

9. How many protons does Mg have?12 How many neutrons does Mg Have? 12

10. The Atom

11. The Electron Cloud Electrons- The number of electrons equals the number of protons Valence Electrons – The outer most electrons – Valence electrons are responsible for bonding

12. Review How many protons? How many neutrons? How many electrons?

13. How many protons? 3 How many neutrons? 4 How many electrons? 3

14. Bohr Model The first shell can have 2 electrons The second shell can have 8 electrons