Chemistry Examples

Find the Number of Neutrons Ar
Step 1
Find the element on the periodic table.
18Atomic Number
ArElement Symbol
ArgonElement Name
39.95Average Atomic Mass
Step 2
The atomic weight is a measurement of the total number of particles in an atom's nucleus including both protons and neutrons. So the first step is to locate the atomic mass on the periodic table, and round the value to the nearest whole number.
round to
Step 3
The mass number is the number of particles in an atom's nucleus. The nucleus is made up of protons and neutrons.
Step 4
Find the element on the periodic table.
18Atomic Number
ArElement Symbol
ArgonElement Name
39.95Average Atomic Mass
Step 5
To find the number of protons in , first locate the element on the periodic table. Next, find the atomic number which is located above the element's symbol. Since 's atomic number is , has protons.
protons
Step 6
Fill in the known values where represents the number of neutrons.
Step 7
Rewrite the equation as .
Step 8
Move all terms not containing to the right side of the equation.
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Step 8.1
Subtract from both sides of the equation.
Step 8.2
Subtract from .