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isotope practice, easy grade. Isotopes are atoms with the same number of protons but that have a different number of neutrons. Since the atomic number is equal to the number of protons and the atomic mass is the sum of protons and neutrons, we can also say that isotopes are elements with the same a...

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CLASS SET

CLASS SET

Isotope Practice 1. Here are three isotopes of an element: a. The element is: carbon b. The number 6 refers to the atomic number c. The numbers 12, 13, and 14 refer to the atomic mass d. How many protons and neutrons are in the first isotope? 6 e.

6

6How many protons and neutrons are in the second isotope? 6 and 7

f. How many protons and neutrons are in the third isotope? 6 and 8

2. Complete the following chart: Isotope name atomic # mass # Potassium-37

19

37

# of protons 19

# of neutrons 18

# of electrons

Oxygen-17

8

17

8

9

8

uranium-235

92

235

92

143

92

uranium-238

92

238

92

146

92

boron-10

5

10

5

5

5

boron-11

5

11

5

6

5

EXTENSION: Average Atomic Mass

19

The atomic mass is the average abundance of all of the isotopes of an element. For example, hydrogen’s atomic mass is 1.01, which means that hydrogen typically contains 1 proton and 0 neutrons; however, one out of one hundred hydrogen atoms will contain one neutron. In order to find the atomic mass, the following formula is used: Average atomic mass = p1M1 + p2M2 +… + pnMn Where p is the percentage (in decimal form) representing the natural abundance of the isotope and M is the mass number of the isotope. Example: Chlorine consists of two major isotopes, one with 18 neutrons (75.77 percent of natural chlorine atoms) and one with 20 neutrons (24.23 percent of natural chlorine atoms). The atomic number of chlorine is 17 (it has 17 protons in its nucleus). To find the average atomic mass, the formula is:

Average atomic mass of chlorine = (.7577)(35) + (.2423)(37) = 35.48

DIRECTIONS: For the following problems, show your work! Be thorough. 3. Naturally occurring europium (Eu) consists of two isotopes was a mass of 151 and 153. Europium-151 has an abundance of 48.03% and Europium-153 has an abundance of 51.97%. What is the atomic mass of europium? 152.04

4. Strontium consists of four isotopes with masses of 84 (abundance 0.50%), 86 (abundance of 9.9%), 87 (abundance of 7.0%), and 88 (abundance of 82.6%). Calculate the atomic mass of strontium. 87.71 5. Titanium has five common isotopes: 46Ti (8.0%), 47Ti (7.8%), 48Ti (73.4%), 49 Ti (5.5%), 50Ti (5.3%). What is the average atomic mass of titanium? 47.92 6. Calculate the atomic mass of copper if copper-63 is 69.17% abundant and copper-65 is 30.83% abundant. 63.62

7. Boron exists in two isotopes, boron-10 and boron-11. Based on the atomic mass, which isotope should be more abundant? boron-11...