Potassium-39 – It has 19 protons and atomic mass is 39.

What is potassium 42 mass number?

Potassium K-42. 14378-21-3. Q27288076. Molecular Weight. 41.962402.

How do you find your mass number?

Together, the number of protons and the number of neutrons determine an element’s mass number: mass number = protons + neutrons. If you want to calculate how many neutrons an atom has, you can simply subtract the number of protons, or atomic number, from the mass number.

What’s the half-life of potassium-40?

The half-life of potassium-40 that decays through beta emission is 1.28 × 109 years, however the half-life of potassium-40 that decays through positron emission is 1.19 × 1010 years.

Is potassium-40 stable?

Its mass energy (or internal energy), however, is actually greater than either of its neighbours – calcium 40 and argon 40. This difference is enough to make potassium 40 unstable. The reason for this is that protons, like neutrons, like to exist in pairs in a nucleus.

What is the mass number made up of?

mass number, in nuclear physics, the sum of the numbers of protons and neutrons present in the nucleus of an atom.

What is the mass number of C 12?

Atomic mass is based on a relative scale and the mass of 12C (carbon twelve) is defined as 12 amu; so, this is an exact number.

What is the mass number of a potassium K atom that has 20 neutrons?

An atom of potassium with 20 neutrons would have a mass number of 39 and thus be an atom of the potassium-39 isotope.

What is mass number plus atomic number?

Atomic Number and Mass Number. Atomic number and mass number are always whole numbers because they are obtained by counting whole objects (protons, neutrons, and electrons). The sum of the mass number and the atomic number for an atom (A-Z) corresponds to the total number of subatomic particles present in the atom.