Different isotopes of the same element have different numbers of what ????

atomic masses are different.

and also different #'s of neutrons too

Different isotopes of the same element have different numbers of neutrons.

Isotopes are atoms of the same element that have the same number of protons in the nucleus but a different number of neutrons. The number of protons determines the element's atomic number, while the sum of the protons and neutrons gives the element's mass number.

To find the number of neutrons in an isotope, you need to know the element's atomic number and mass number. The atomic number is typically denoted by the letter "Z," and the mass number is denoted by the letter "A." The number of neutrons can be calculated by subtracting the atomic number (Z) from the mass number (A). Mathematically, it can be represented as:

Number of neutrons = Mass number (A) - Atomic number (Z)

For example, let's consider carbon. Carbon has three naturally occurring isotopes: carbon-12, carbon-13, and carbon-14. The atomic number of carbon is 6, which means it has 6 protons in the nucleus. The isotopes have mass numbers of 12, 13, and 14, respectively. By using the formula mentioned above:

Number of neutrons in carbon-12 = 12 - 6 = 6
Number of neutrons in carbon-13 = 13 - 6 = 7
Number of neutrons in carbon-14 = 14 - 6 = 8

So, different isotopes of carbon have different numbers of neutrons.