The sun is composed of 74 percent hydrogen (measured by mass), an element whose nucleus is a single proton.

The Bohr model, applies only to a single proton and a single electron, so exceptions are no surprise.

But in 1970 an unknown form of nuclear radioactivity was discovered: a decay process that emits single protons.

Their radioactive decay is accompanied by the emission of single protons.

The simplest ion is the hydrogen nucleus, a single proton.

Its weight is primarily due to its single proton.

Atomic hydrogen is simple, consisting of one electron orbiting a single proton.

In nature, the commmon form of the hydrogen atom has a nucleus of a single proton.

Assuming that he moved the lever by one metre, the Earth would move by less than the diameter of a single proton.

Most hydrogen atoms bound in water molecules have a single proton for a nucleus.