1. TOPIC 1: Isotopes

2. Potassium-39 93.25% Potassium-40 6.73% Potassium-41 0.12% PROTONS ELECTRONS NEUTRONS 19 20 2221 There are 3 isotopes of K atoms

3. What are isotopes? -ATOMS OF THE SAME ELEMENT: WITH the same # of but DIFFERENT NUMBER OF NEUTRONS p+

4. Example 1:

5. Example 2:

6. 5 Postulates of Dalton’s Atomic Theory Which two are incorrect?.......Why? 1.All matter is made of extremely small particles called atoms. 2.All atoms of a given element are identical, having the same size, mass, and chemical properties. Atoms of a specific element are different from those of any other element. 3.Atoms cannot be created, divided into smaller particles, or destroyed. 4.Different atoms combine in simple whole- number ratios to form compounds. 5.In a chemical reaction, atoms are separated, combined, or rearranged.

7. Two ways to write the symbol for an isotope: K 19 39 Mass # Potassium- 39 Atomic # Mass Number = # protons + # neutrons

8. How many p +, e -, & n 0 are contained in each of the following atoms? 1. gallium - 64 p+ = 31 e- = 31 2. 132 Cs 55 p+ = 55 e- = 55 64-31  n 0 = 33 132-55  n 0 = 77

9. Isotope Similarities: b. Chemically and Physically alike Why? a. Same # of p+ and e - Same # of valence electrons  determine chemical behavior

10. Isotope Differences: a. Different # of neutrons c. Different masses b. Different mass numbers

11. isotope Atomic # Mass # #P+#P+ #E-#E- #n0#n0 Symbol NEON- 22 22 Calcium-46 26 10 1210 Ne 204620 Ca 10 22 46 20