Calculating the Mass & Neutrons Practice

How to:

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Calculate an atom's mass

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​Calculate the neutrons in an atom

​By: Ms. LaLonde-Bernal

To calculate the mass of an atom you add the protons and the neutrons.

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Atomic mass = protons + neutrons

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To calculate the number neutrons in an atom. Subtract the number of protons (the atomic number) from the atomic mass (the number of protons + neutrons).

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Neutrons = Atomic mass - protons

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Multiple Choice

How many neutrons are in one atom of the element shown?

ROUND the atomic mass to the nearest whole number.

Example: 26.982 rounds to 27

• 27

• 13

• 26.98

• 14

Multiple Choice

How many neutrons are in one atom of the element shown?

ROUND the atomic mass to the nearest whole number.

Example: 26.982 rounds to 27

• 30

• 26

• 55.847

• 56

Multiple Choice

How many neutrons are in one atom of the element shown?

ROUND the atomic mass to the nearest whole number.

Example: 26.982 rounds to 27

• 28

• 57

• 58.69

• 31

Multiple Choice

How many neutrons are in one atom of the element shown?

ROUND the atomic mass to the nearest whole number.

Example: 26.982 rounds to 27

• 3

• 7

• 4

• 6.94

Multiple Choice

How many neutrons are in one atom of the element shown?

ROUND the atomic mass to the nearest whole number.

Example: 26.982 rounds to 27

• 26

• 30

• 55

• 55.85