Question

One atomic mass units is equivalent to ____ Mev energy

Answer 1

Hint: An atom is composed of two regions. One region is in the center of the atom containing protons and neutrons are called a nucleus and the other which is the outer region holds electrons in orbit around the nucleus. Protons and neutrons have approximately the same mass known as an atomic mass unit (amu) or one Dalton.

Complete step by step solution:
1 atomic mass unit (amu) = $1.67X{{10}^{-24}}gms$
The atomic mass unit value is approximately equal to the same value of protons and neutrons. Protons are positively charged particles and neutrons are having no charge. Hence, the number of neutrons contributes to the mass of the atom, not the charge of the atom.
Electrons are much smaller than protons or neutrons $\dfrac{1}{1800}amu$ . Hence, the mass of electrons can be ignored when considering the atomic mass of an atom based on protons and neutrons only.
Atomic number (Z) and mass number (A): the number of protons in an element is known as the atomic number of elements and the number of protons and neutrons in an element is known as mass number.
Atomic mass = number of protons + number of neutrons
1 atomic mass unit is converted into energy units by using the below equation,
$E=m{{c}^{2}}$
Where, speed of light $c=3X{{10}^{8}}m/\sec $
Atomic mass unit, $m=1.67X{{10}^{-24}}gms$
Substitute these values in the above equation,
$E=1.67X{{10}^{-24}}X{{(3X{{10}^{8}})}^{2}}=1.49X{{10}^{-10}}J$
1 MeV = $1.66X{{10}^{-13}}J$
We know that,
E = $\dfrac{1.49X{{10}^{-10}}}{1.6X{{10}^{-13}}}=931.5MeV$


Hence, one atomic mass units are equivalent to 931.5 MeV energy

Note: For an element, consider all its naturally occurring isotopes, then the average mass of an atom is called the atomic mass of an element. The atomic mass is calculated by obtaining the mean of the mass number of its isotopes.