Question

Why is the mass number of an element always greater than or equal to its atomic number?

Answer 1

1 atomic mass unit (amu) is defined as the mass of 1/12 of the mass of a carbon-12 atom. I agree with other people that atoms usually contain neutrons and protons which makes it heavier. Hydrogen comes closests because it usually doesn't contain a neutron. I hope that helps.

Answer 2

the mass number of an element is found by adding up the number of protons and the number of neutrons in the nucleus.. . the atomic number of an element is equal to the number of protons in the nucleus.. . therefore, the mass can never be lower than the atomic number since the element that makes up the atomic number is also part of what makes up the mass.

Answer 3

Because, the atomic number is the number of protons in an atom; the mass number is the number of protons AND neutrons in an atom's nucleus.. . Since you can't have a negative number of neutrons, the mass number will never be less than the atomic number.

Answer 4

The atomic number is simply the count of the number of protons at the center of an element.. . The mass number is basically the sum of the protons + neutrons. Since an element is not determined by the number of neutrons at the center, all elements have isotopes with different number of neutrons in the center. The mass is typically some averaged out number based on the frequency the isotopes occur in nature.

Answer 5

I would answer, but propheticwalnut's answer is great.

Answer 6

The mass number represents the total number of protons and neutrons within the atom, the atomic number represents only the number of protons. As the number of neutrons can never be negative than the mass number is always equal to or greater than the atomic number.