1. Isotopes and Ions

2. Fill in the following table: Symbol Atomic Mass Atomic Number # of protons # of neutrons # of electrons Na Na Ne Ne Hg Hg Zn Zn Al Al 23 11 20 10 201 80 65 30 27 13

3. Fill in the following table: Symbol Atomic Mass Atomic Number # of protons # of neutrons # of electrons 1275354 Cd Cd112 385036 X7554 X10342 2+ 2- 3+

4. What is an Ion? An atom that is positively or negatively charged An atom that is positively or negatively charged An atom that is positively charged has ____ electrons than the number of protons An atom that is positively charged has ____ electrons than the number of protons An atom that is negatively charged has ____ electrons than the number of protons An atom that is negatively charged has ____ electrons than the number of protons

5. What is an Isotope? Atoms of the same element that contain different numbers of neutrons Atoms of the same element that contain different numbers of neutrons Example: Example:  Nitrogen has two isotopes: Nitrogen-14 ( 14 N) and Nitrogen-15 ( 15 N)  Nitrogen 14 has _________ neutrons  Nitrogen 15 has _________ neutrons

6. Determining the average atomic mass The average atomic mass (  of an element depends on the proportions of the isotopes. Sample 1: 10 B = 18.8% 11 B = 81.2% Average = (% 10 B)(mass of 10 B) + (% 11 B)(mass of 11 B) = (0.188)(10) + (0.812)(11) = 1.88 + 8.982 = 10.812  The average atomic mass for Boron is 10.812 

7. Determine the % of each isotope Given the average atomic mass and the isotopes present in the mixture, the % of each isotope present can be calculated. Example: Calculate the % of each isotope present in the mixture of 107 Ag and 109 Ag that has an average mass of 107.9  Let x represent 107 Ag and (1-x) represent 109 Ag 107 x + 109 (1 – x) = 107.9 107 x + 109 – 109 x = 107.9 2 x = 1.1 x = 0.55 1 – x = 0.45 Therefore 107 Ag = 55% and 109 Ag = 45%