1. Isotopes A study inside the nucleus of an atom

3. Atomic number (A) = number of protons in nucleus Mass Number (Z) = number of protons + number of neutrons OR OR atomic number (A) + number of neutrons Isotopes are atoms of the same element (X) with different numbers of neutrons in the nucleus A Z Mass Number Atomic Number Element Symbol X U 92 235 U 92 238 H (D) 1 2 1 1 H H (T) 1 3

4. 1 1 H 1 2 H 1 3 H Examples of hydrogen isotopes...

5. What is it that keeps protons and neutrons together in the nucleus of an atom? Protons are + charged and will naturally repel each other. Nonetheless, they they are stuck in a nucleus together with neutrons. These neutrons are uncharged (neutral) but act as “buffers” to keep the protons apart and therefore reduce the repelling electric force. The force that holds a nucleus together is called a strong nuclear force which holds protons together only if they are nearly touching, which is common in a nucleus.

6. How many protons, neutrons, and electrons are in 14 C 6 ? 6 protons, 8 (14 - 6) neutrons, 6 electrons 6 protons, 9 (15 - 6) neutrons, 6 electrons Do You Understand Isotopes? How many protons, neutrons, and electrons are in ? 15 C 6

7. 14 C 6 = carbon-14 82 protons, 132 (214 - 82) neutrons, 82 electrons More... How many protons, neutrons, and electrons are in ? 214 Pb 82 15 C 6 = carbon-15 241 Am 95 = americium-241 218 Po 84 = polonium-218 3 H 1 = hydrogen-3 Pb = lead... by the way 131 I 53 = iodine-131

8. More information can be found on pages 47-48 in your textbooks. Please get started on your worksheet about isotopes. See examples below: 196 Ra 88 = ____ protons ____ neutrons ____ electrons 88 108 88 = ____ protons ____ neutrons ____ electrons phosphorus-55 40 15