1. Isotopes

2. COPY THIS PICTURE INTO YOUR NOTES AND USE COLOR!
It doesn’t have to be the same colors as here, just three different colors! DON’T FORGET THE KEY!!!

3. Notation

4. Other ways to write elements:36
17Cl Cl-36
Chlorine-36
Mass Number
Mass Number
Atomic Number

5. Isotopes of an element have different mass numbers because they have
different numbers of neutrons,
but they have
the same atomic number.

7. Example: Isotopes of Carbon and Hydrogen
protium deuterium tritium
H H H
Isotopes of Hydrogen
Isotopes of Carbon

8. COPY THIS INTO YOUR NOTES AND THEN ANSWER
Isotopes?
COPY THIS INTO YOUR NOTES AND THEN ANSWER
Which of the following represent isotopes of the same element? Which element?
Explain why!
X 235 X 238 X X

9. Learning Check – Counting
COPY THIS INTO YOUR NOTES AND THEN ANSWER
Naturally occurring carbon consists of three isotopes, 12C, 13C, and 14C. State the number of protons, neutrons, and electrons in each of these carbon atoms. 12C 13C 14C #p+ _______ _______ _______ #no _______ _______ _______ #e- _______ _______ _______

10. Answers
12C C 14C #p
#no #e

11. COPY THIS INTO YOUR NOTES AND THEN ANSWER
Learning Check
COPY THIS INTO YOUR NOTES AND THEN ANSWER
An atom has 14 protons and 20 neutrons. A. Its atomic number is 1) 14 2) 16 3) 34 B. Its mass number is C. The element is 1) Si 2) Ca 3) Se D. Another isotope of this element is 1) 34X 2) 34X 3) 36X