1. Atomic Structure: Atoms and Isotopes GPS 5

2. Simplified Model of the Atom Nucleus – the center of the atom that contains protons and neutrons Electron cloud – area surrounding the nucleus containing only electrons Proton – particle within the nucleus that has a positive one (+1) charge Neutron – particle within the nucleus that has no charge (neutral particle) Electron – particle within the electron cloud that has a negative one (-1) charge

3. Simplified Model of the Atom Subatomic Particle Actual MassRelative Mass (amu) Relative Charge Location Proton1.67 x 10 -27 kg1+1Nucleus Neutron1.67 x 10 -27 kg1No chargeNucleus Electron9.11 x 10 -31 kg0Electron Cloud

4. Reading the Periodic Table Atomic number – Equals the number of protons in a particular element – No two elements have the same atomic number Atomic mass (a.k.a. Mass number) – Equals the number of protons plus the number of neutrons in a particular atom – Given in atomic mass units (amu)

5. Finding the Number of Subatomic Particles Example: Number of protons (p) = Number of neutrons (n) = Number of electrons (e) = atomic number p = 6 mass number – atomic number n = 6 number of protons e = 6

6. Finding the Number of Subatomic Particles Find the number of protons, neutrons, and electrons for the following elements: – Nitrogen – Potassium p = 7, n = 7, e = 7 p = 19, n = 20, e = 19

7. Periodic Table: A little funny

8. Isotopes -neutral atoms with the same number of protons and electrons, but with a different number of neutrons Example: How many neutrons does Carbon-18 have? Example: IsotopeProtonsNeutronsElectrons Carbon-12666 Carbon-13676

9. Calculating Average Atomic Mass IsotopePercent abundance Fractional abundance Carbon-1298.93%0.9893 Carbon-131.07%0.0107 Average atomic mass = (isotope mass #1)(fractional abundance #1) + (isotope mass #2)(fractional abundance #2) + … Example: Average atomic mass = (12)(0.9893) + (13)(0.0107) Average atomic mass = 12.0 u

10. Calculating Average Atomic Mass Find the average atomic mass using the element’s isotope information: IsotopePercent abundance Fractional abundance unknown-1818.14%0.1814 unknown-1981.86%0.8186 Average atomic mass = 18(0.1814) + 19(0.8186) Average atomic mass = 18.82 u