2. Parts of the Atom Notes

3. Contains: Contains: __________ and __________ ______________ with relative mass _________ _________ ______________ and relative charge _________ _________ ______________ “amu” stands for _________ _________ _______ Parts of the Atom: 2 parts: ________ and electron cloud Nucleus ProtonsNeutronsElectrons atomic mass unit + _ NONE!!! 1 amu 0 (too small to have mass)

4. Relationships between Particles 1.Atomic number is the # of ___________________ 2.Mass number is the # of ________ + ________ protons neutrons What is the atomic mass of this atom?? 12

5. 3.Chemical reactivity is determined by the ___________________ 4.Atoms are neutral when ___________________protons = electrons electrons

6. What happens when atoms gain or lose electrons? They become (+ ) or (-) charged.

7. Called: ____________ Called: __________ Called: __________ Atomic # Atomic mass To calculate # of neutrons: _______________________________ atomic mass – atomic #

8. Atomic number = # of protons # of protons determines ________________ Who is element # 15? How many protons does lithium have? What is the atomic number of tin? which element it is!! P (Phosphorous) 3 protons 50

9. Symbol for Generic “X” Element: X ______________ Mass #, A Atomic #, Z ( # ____________ ) P + N P

10. 24.305 Magnesium 12 Mg Periodic Table: Mg 24 12