TOPIC 1: Isotopes

1. TOPIC 1:Isotopes

2. There are 3 isotopes of K atoms 19 19 19 19 19 19 21 22 20

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

4. Example 1:

5. Example 2:

6. 5 Postulates of Dalton’s Atomic TheoryWhich two are incorrect?.......Why? All matter is made of extremely small particles called atoms. 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. Atoms cannot be created, divided into smaller particles, or destroyed. Different atoms combine in simple whole-number ratios to form compounds. In a chemical reaction, atoms are separated, combined, or rearranged.

7. Two ways to write the symbol for an isotope: 1. 2. Mass # 39 K Potassium- 39 19 Atomic # Mass Number = # protons + # neutrons

8. How many p+, e-, & n0 are contained in each of the following atoms? 1. gallium - 64 p+ = 31 e- = 31 64-31 n0= 33 p+ = 55 e- = 55 • 132 Cs 55 132-55 n0= 77

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

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

11. 22 Ne 10 10 10 12 10 46 Ca 20 46 20 20 20