# Worksheet: Atomic Numbers and Mass Numbers

In this worksheet, we will practice defining and calculating the atomic numbers of elements and mass numbers of isotopes.

Q1:

Neon has an atomic number of 10. How many protons are there in an atom of neon?

Q2:

An aluminum atom has an atomic number of 13 and a mass number of 27.

How many protons are there in an atom of aluminum?

How many neutrons are there in an atom of aluminum?

How many electrons are there in an atom of aluminum?

Q3:

A fluorine atom has an atomic number of 9 and a mass number of 19.

How many protons are there in an atom of fluorine?

How many neutrons are there in an atom of fluorine?

How many electrons are there in an atom of fluorine?

Q4:

A carbon atom has an atomic number of 6 and a mass number of 12.

How many protons are there in an atom of carbon?

How many neutrons are there in an atom of carbon?

How many electrons are there in an atom of carbon?

Q5:

An atom of silicon has an atomic number of 14. How many electrons are there in an atom of silicon?

Q6:

An atom of sodium has a mass number of 23. What is the total number of protons and neutrons in the nucleus of the atom?

Q7:

An atom of calcium has a mass number of 42 and an atomic number of 20. How many neutrons are there in its nucleus?

Q8:

An atom of chlorine has a mass number of 35. What is the total number of protons and neutrons in its nucleus?

Q9:

An atom of sulfur has 16 protons in its nucleus. What is the atomic number of sulfur?

Q10:

The atomic number of helium-4 is half its mass number. How many neutrons are there in an atom of helium-4?

Q11:

Hydrogen-1 has an atomic number of 1. How many neutrons are there in an atom of hydrogen?

Q12:

Phosphorus-31 has an atomic number of 15. How many neutrons are there in an atom of phosphorus-31?

Q13:

Nuclide notation is used to summarize some of the properties of an atom or an ion. Which of the following properties is not directly expressed in nuclide notation?

• ACharge
• BMass number
• CAtomic number
• DElement symbol
• ENeutron number

Q14:

The isotope hydrogen-1 has the nuclide symbol .

How many protons are there in atoms of hydrogen-1?

How many neutrons are there in atoms of hydrogen-1?

What is the mass number of hydrogen-1?

Q15:

The isotope oxygen-18 has the nuclide symbol .

How many protons are there in atoms of oxygen-18?

How many neutrons are there in atoms of oxygen-18?

What is the mass number of oxygen-18?

Q16:

In nuclide notation, which position is occupied by the mass number?

• A
• B
• C
• D

Q17:

In nuclide notation, which position is occupied by the atomic number?

• A
• B
• C
• D

Q18:

Which of the following nuclides has the greatest number of neutrons?

• A
• B
• C
• D
• E

Q19:

The isotope iridium-193 has the nuclide symbol .

How many protons are there in atoms of iridium-193?

How many neutrons are there in atoms of iridium-193?

What is the mass number of iridium-193?

Q20:

Which of the following nuclides has the lowest number of neutrons?

• A
• B
• C
• D
• E

Q21:

What is the nuclide symbol for the isotope of oxygen with the same number of neutrons and protons?

• A
• B
• C
• D
• E

Q22:

What is the nuclide symbol for the isotope of carbon with two more neutrons per nucleus than carbon-12?

• A
• B
• C
• D
• E

Q23:

What is the nuclide symbol for carbon-12?

• A
• B
• C
• D
• E

Q24:

What is the nuclide symbol for tritium, a hydrogen isotope with two neutrons?

• A
• B
• C
• D
• E

Q25:

What is the nuclide symbol for oxygen-16?

• A
• B
• C
• D
• E