Calculate the number of neutrons for the isotopes of Neon with mass numbers 17, 19, and 21. The atomic number of Neon is 10.

The number of neutrons in an atom is calculated by subtracting the atomic number (number of protons) from the mass number (total number of protons and neutrons).

$$\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$$

Given: Atomic number of Neon (Ne) = 10.

• For the isotope with mass number 17: $$\text{Number of neutrons} = 17 - 10 = 7$$
• For the isotope with mass number 19: $$\text{Number of neutrons} = 19 - 10 = 9$$
• For the isotope with mass number 21: $$\text{Number of neutrons} = 21 - 10 = 11$$

The number of neutrons in the isotopes are:

• Mass number 17: $\boxed{\text{7 neutrons}}$
• Mass number 19: $\boxed{\text{9 neutrons}}$
• Mass number 21: $\boxed{\text{11 neutrons}}$