Atom X has atomic mass (A) = 40 and atomic number (Z) = 20. Atom Y has A = 42 and Z = 20. How are these two atoms related?
They are isotopes of element 20
Atoms X and Y are isotopes of the same element. They have the same atomic number (Z), which means they have the same number of protons in their nucleus. However, they have different atomic masses (A), which means they have different numbers of neutrons in their nucleus. Since the number of protons is the same, they are both the same element, but their atomic masses differ due to the variation in the number of neutrons.
These two atoms, Atom X and Atom Y, are related as isotopes of the same element.
Isotopes are atoms of the same element that have the same atomic number (Z), which means they have the same number of protons in their nucleus, indicating they belong to the same element. However, they have different atomic masses (A), which means they have a different number of neutrons in their nucleus.
In this case, both Atom X and Atom Y have the atomic number (Z) of 20, which indicates that they both belong to the element with 20 protons, which is calcium (Ca).
Atom X has an atomic mass (A) of 40, which means it has 20 neutrons in its nucleus (A - Z = neutrons). Atom Y, on the other hand, has an atomic mass of 42, which indicates that it has 22 neutrons.
So, Atom X and Atom Y are isotopes of calcium, with Atom X having 20 neutrons and Atom Y having 22 neutrons.