Why can't the mass number be smaller than the atomic number?

Answer 1

The mass number has to be greater then the atomic number because the mass number is the protons plus the neutrons. If you were to take 10-12 you would get a negative number of 2 and there can't be a negative number of neutrons!

Answer 2

The mass number of an atom represents the total number of protons and neutrons in its nucleus, while the atomic number represents the number of protons. Since neutrons contribute to the mass number but not the atomic number, the mass number must always be equal to or greater than the atomic number.

Answer 3

The atomic number of an element is how many protons that element has, then you have to take in how many neutrons it has then add that together to get you mass number. The mass number is how many protons+neutrons you have i an element, and the atomic number is how many protons you have in an atom. But the Atomic Mass is the average of the normal elements Atomic number+ the elements isotopes atomic number. SO you can't have an atomic mass less then an atomic number.

Answer 4

The atomic number of an element is the number of protons in the nucleus of that element (and in any isotope of that element). The mass number of an element is the number of protons plus the number of neutrons in the nucleus of that element (and that number will differ for each isotope of that element). In any given element (save hydrogen) there are always one or more neutrons in the nucleus. As the atomic number is just the number of protons, it will always be less than the number of protons plus the number of neutrons. Always. The "outcast" is hydrogen. Most hydrogen has just a single proton in the nucleus. That means for those atoms of hydrogen, the atomic number (number of protons) and the mass number (number of protons plus the number of neutrons) will be one. (Recall that there are no neutrons in "regular" hydrogen.) Hydrogen does have two other isotopes. One has one neutron and the other has two neutrons. The atomic number for each of those two isotopes is still one, but their mass numbers will be two and three, respectively.

Answer 5

The Atomic number of an atom is the same as the number of protons in the nucleus. The amount of neutrons in the atom will be roughly the same as that, because atoms have 'isotopes' with either a few more or a few less Neutrons than 'normal'.

Magnesium is the element with the Atomic number of 12, and normally has 12 neutrons too, giving it an atomic weight of 24. To make Magnesium have an atomic weight of 10, it would have to lose all its neutrons (impossible) and two protons too (which would change its proton number, making it Neon)

Answer 6

The mass number is defined as the number of protons and the number of neutrons in the atom. The atomic number is the number of protons in an atom. If the atomic number is 12(number of proton) and the mass number is 10 (number of proton PLUS neutrons) you would have -2 neutrons, which is not possible.

Answer 7

The atomic number is equal to the number of protons in the nucleus, whereas the atomic mass depends upon the sum of the mass of the protons and the neutrons (there are also electrons but they have much less mass than protons or neutrons). Almost every type of atom has both protons and neutrons, the single exception being the hydrogen 1 isotope, which consists of one proton with one electron.

Answer 8

The mass number is the sum of the protons and neutrons in an atom of an isotope of a particular element. The number of protons is the atomic number, and gives the element its identity. So mass number cannot be less than the number of protons (atomic number).

Answer 9

We make atomic number by number of protons in a atom. We make mass number by total of both protons and neutrons.

Answer 10

The atomic number can't be greater than the mass.