Hydrogen and Helium Nucleus (English)

1-2: Hydrogen and Helium Nucleus

[Nucleus of the Hydrogen Atom = Proton]

Rutherford thought that

the nucleus of the lightest atom,

i.e. hydrogen nucleus,

is one of the fundamental particles

in the Nuclear World,

i.e. the World of the Atomic Nucleus.

He named this particle "proton",

because Greek proton means

"first".

Namely, the proton is

none other than the hydrogen ion,

so that its electric charge

is +e.

It was made clear by

Rutherford's experiment of

the artificial transmutation of elements

that the proton is one of

the fundamental constituents

of atomic nuclei (1919).

[Nucleus of the Helium Atom = Alpha Particle]

Alpha particles emitted from

the radioactive elements such as

radium and polonium

are doubly ionized helium

i.e. the helium atom having

lost two electrons.

This was confirmed by Rutherford

and his student, Royds,

in 1908.

(See the page of

"Microscopic World -1-:

2-3: Scattering of Alpha Particle by an Atom").

From these investigations,

it was clarified that

the mass of an alpha particle

is four times as large as

the proton mass,

and the electric charge is

twice as much as that of the proton,

i.e. +2e.

[What is the alpha particle made of ?]

It was clear that

the proton is contained

in a nucleus.

Then, what are the other constituents

of a nucleus?

In Rutherford's days,

people knew the existences of

electron and proton.

Then is it possible to constitute

an alpha particle by combining

these two kinds of particles,

electrons and protons?

We may consider that

the alpha particle consists

of four protons

and two electrons

combining together with each other.

This idea appears

plausible enough

in view of both mass and charge.

However, this idea has a serious defect

and is unacceptable,

as will be discussed

on the next page.

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