2. ELECTRONS, PROTONS AND NEUTRONS

3. ATOMIC AND MASS NUMBER

5. AtomicNumber Protons and neutronsformthesmall dense nucleus. Electronsoccupymost of theatomsvolume. Atomsdifferbythenumber of protons in theirnucleus. AtomicNumber: isthenumber of protons in thenucleus of theatom of thatelement. (thisnumberidentieftheelement) Atoms are electrically neutral # of protons = # of electrons

6. RelatedProblems Theelementnitrogen (N) isatomicnumber 7. Howmanyprotons and electrons are in a nitrogenatom? Whyisanatomelectrically neutral? Whatistherelationshipbetweenthenumber of protons and theatomicnumber of anatom?

7. MassNumber MassNumberisthe total number of protons and neutrons in thenucleus. Anatomscomposition can be determinedfromitsatomicnumber and massnumber # of Neutrons= Mass # - Atomic #

8. RelatedProblems Howmanyprotons, electrons, and neutrons are in thefollowingatoms?

9. RelatedProblems Complete thefollowingtable: