Question

Write the approximate mass of the proton, neutron, and electron in a.m.u.

Answer 1

Hint: It was presumed before that there were only two particles that are protons and electrons. Positively charged particles are called protons and negatively charged particles are called electrons. Later that only the chargeless particles were found and they are called Neutrons. The value of one atomic mass unit is constant for all the particles.

Complete step by step answer:
The mass of the protons, neutrons, and electrons in the atomic mass unit:
PROTONS:
Protons are the positively charged particles found in the nucleus of the charged atom. It is fundamentally a subatomic particle. The mass of protons in kilograms:
$ \Rightarrow {m_p} = 1.672621898 \times {10^{ - 27}}kg$
Expressing the mass in a.m.u(atomic mass unit):
\[ \Rightarrow 1a.m.u = 1.66053904E\]
Multiply these masses,
$ \Rightarrow {m_p} = 1.672621898 \times {10^{ - 27}}kg \times 1.66053904E$
$\therefore {m_p}\left( {a.m.u} \right) = 1.007276\left( {91} \right)a.m.u$
NEUTRONS:
A scientist named James Chadwick founded chargeless neutral particles when he bombarded the beryllium with the alpha particles. This bombardment of the particles led to extremely powerful penetrations that could not be deflected by the magnetic or electric fields.
He found these neutral chargeless particles and named them Neutrons. Neutrons are subatomic particles that have no charge.
The approximate mass of the neutron in a.m.u:
The mass of a neutron is ${m_n} = 1.6726231 \times {10^{ - 27}}kg$
The mass given here is expressed in $kg$. To express the unit in a.m.u.
$ \Rightarrow 1Kg = 6.0229552894949E + 26a.m.u$
Therefore,
Multiply these masses,
\[ \Rightarrow 1.6749286 \times {10^{ - 27}}kg = 1.6749286 \times {10^{ - 27}}kg \times 6.0229552894949E + 26\]
\[\therefore {m_n}\left( {a.m.u} \right) = 1.008664904\left( {14} \right)a.m.u\]
ELECTRONS:
The negatively charged particles that revolve around the nucleus are called Electrons. The mass of the electrons:
The mass of the electrons expressed in kilograms:
$ \Rightarrow 9.10938356 \times {10^{ - 31}}kg$
The mass of electrons in a.m.u:
\[ \Rightarrow 1a.m.u = 1.66053904E\]
Multiply the values.
$ \Rightarrow 9.10938356 \times {10^{ - 31}}kg \times 1.66053904E$
$\therefore {m_e} = 5.4857990970 \times {10^{ - 4}}a.m.u$

Note:
The mass of neutrons is slightly greater than that of the mass of protons. Protons are the part of atomic nuclei that consists of the basic particles called Quarks and Gluons. Electrons belong to a group of the lepton family of the first generation. It has no known structure and hence it is called elementary particles.