4. Atoms and Elements

Isotopes of an element differ in their:

A period 5 transition metal has 51 neutrons. If the element is yttrium, what is the mass number of this isotope? (Atomic number of Y is $39$.)

Which element is described by an atom that has 35 protons and 45 neutrons?

Which of the following correctly represents a bromine isotope that has 46 neutrons?

Copper has atomic number 29. How many neutrons are in an atom of the isotope copper-63?

How many neutrons are in a ${\mathrm{He}}^4$ atom?

Which element is represented by an atom that has 9 protons and 10 neutrons?

In terms of subatomic particles, how does one isotope of an element differ from another isotope of the same element?

How many neutrons are in an atom of magnesium-25 (${\mathrm{Mg}}^{25}$)? (Assume magnesium has atomic number $12$.)

Which nuclide has 18 neutrons?

Copper has two naturally occurring stable isotopes, $C_{29}{u}^{63}$ and $C_{29}{u}^{65}$. Which statement correctly compares these two isotopes?

How many neutrons are in a neutral atom of sodium-23, $N_{23}^{11}$?

Isotopes of an element differ in the number of which subatomic particle?

An atom has 25 protons and 30 neutrons. Which element is it?