Name________________________________________ Date_______________
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9
ISOTOPES OR DIFFERENT ELEMENTS
Directions: Write down in the blank if they are isotopes or different elements. Remember:
Isotopes have different numbers of neutrons, different elements have different numbers of
protons.
1) Element D has 6 protons and 7 neutrons
_______________
Element F has 7 protons and 7 neutrons
2) Element J has 27 protons and 32 neutrons
_______________
Element L has 27 protons and 33 neutrons
3) Element X has 17 protons and 18 neutrons
_______________
Element Y has 18 protons and 17 neutrons
4) Element Q has 56 protons and 81 neutrons
_______________
Element R has 56 protons and 82 neutrons
5) Element T has an atomic number of 20 and an atomic mass of 40
Element Z has an atomic number of 20 and an atomic mass of 41.
_________________
6) Element W has 8 protons and 8 neutrons
Element V has 7 protons and 8 neutrons
_________________
7) Element P has an atomic number of 92 and an atomic mass of 238
Element S has 92 protons and 143 neutrons
_________________
ATOMIC MATH
Calculate the atomic number of element X by doing the following
arithmetic. Write answers and SHOW WORK!! in the blanks.
1) Multiply the atomic number of hydrogen by the number of electrons in
mercury, which has an atomic number of 80._____________________
2) Divide this number by the number of neutrons in helium, atomic
number 2, mass number 4._______________________
3) Add the number of protons in potassium, atomic number 19.
_________________________
4) Add the mass number of the most common isotope of carbon.
_________________________
5) Subtract the number of neutrons in sulfur, atomic number 16, mass
number 32.
_________________________
6) Divide by the number of electrons in boron, atomic number 5, mass
number 11.
_________________________
7) You now have the atomic number of element X. Which of the following
elements is X:
Please circle!!
Oxygen, atomic number 8
Fluorine, atomic number 9
Neon, atomic number 10
Sodium, atomic number 11
Magnesium, atomic number 12
Aluminum, atomic number 13
CALCULATING THE AVERAGE ATOMIC MASS
OF AN ELEMENT
The isotopic composition for potassium and neon are listed below.
Calculate the average atomic mass for each element.
MUST SHOW WORK TO GET CREDIT!!
a. Potassium-39
93.10%
b. Potassium-40
0.01%
c. Potassium-41
6.89%
a. Neon-20
90.92%
b. Neon-21
0.26%
c. Neon-22
8.82%
RELATING AVERAGE ATOMIC MASS TO
REAL LIFE
1) If a class has 30 students in it and 20% are boys, how many girls are
in the class?
2) If a student had a 70% on tests, 85% on quizzes and 95% on
homework, what was their final grade? (Tests=50%, Quizzes=30%,
Homework=20%)
3) Mutual funds are stocks where you can invest in more than one
company. If you invest 20% with Coca-Cola, 40% with Microsoft, and
40% with Burger King, how much money will you invest with each
company if you use $10,000 dollars?
4) If Burger King goes bankrupt and you lose all your money in that
stock, how much would you have left?
5) Why do you think people like to use mutual funds?
6) When Wall Street crashed, do you think mutual funds made money?
Why?