Atomic Calculations-Teacher Answer Key
1. Determine the number of protons, neutrons and electrons for the following elements.
Example Elements
Number of
Number of
Number of

Protons
Neutrons
Electrons
Hydrogen (H)
1
0
1
Lithium (Li)
3
4
3
Boron (B)
5
6
5
Oxygen (0)
8
8
8
2.	Which element has a greater number of protons - Potassium (K) or Selenium (Se)?
Potassium has 19 protons and Selenium has 34 according to the elements' atomic numbers.
3.	Which element has a smaller number of electrons - Copper (Cu) or Silver (Ag)?
Copper has 29 electrons, and Silver has 47 electrons, equaling the number of protons in each
element.
4.	Which element has a greater number of neutrons - Magnesium (Mg) or Tin (Sn)?
Magnesium has 12 neutrons and Tin has 69, calculated by subtracting the atomic number from
the atomic mass (rounded to a whole number).
vvEPA
Environmental Protection RadTown Radioactive Atom Activity Set	EPA 402-B-19-018
Agency	https://www.EPA.gov/RadTown/Activitv-2-Atomic-Math-and-Shorthand

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