1. Topic 2/12 Overview 2.1: The Nuclear Atom 2.2: Electron configuration
12.1: Electrons in Atoms

2. A simple diagram

3. A more accurate depiction
Femtometer: 1 fm = 10−15 m

4. Subatomic Particles (+) 1.6*10-19 C (-) 1.6*10-19 C Proton Neutron
Electron
Charge
(+) 1.6*10-19 C
(-) 1.6*10-19 C
Mass
1.67*10-27 kg
1.68*10-27 kg
9.1*10-31 kg
Relative mass 1
1/1836 = 5.5*10-4
Place in atom
Nucleus
Energy Levels

5. Atom Information

6. Atoms vs Ions

7. How do we determine relative abundance?

8. Average = (0.79)(24 amu) + (0.10)(25 amu) + (0.11)(26amu) = 24.31 amu
Average Atomic Mass
Average =
(0.79)(24 amu) +
(0.10)(25 amu) +
(0.11)(26amu)
= amu

9. (Average) Atomic Mass

10. Thyroxine and your Thyroid Gland

11. Symptoms of Iodine Deficiency: Goiter

12. Exact atomic mass (amu) Relative Abundance (%)
Learning Check
Calculate the average atomic mass of silicon based on the following abundance data.
Isotope
Exact atomic mass (amu)
Relative Abundance (%)
Silicon-28
92.21
Silicon-29
4.70
Silicon-30
3.09

13. How do we know relative abundances?

14. Mass Spec Visuals

15. A Naturally Occurring Sample of Mg
Isotopes(def.)-
Relative abundance (def.)-

16. Calculate the atomic mass of magnesium based on the mass spectrum below.