I cant entirely tell for now but an article on rodioactivity should solve the problem
When looking down the groups the elements have an equal number of electrons in the outer shell. This means they react in a similar way making it easier for scientists to use.
Most ions tend to be D. Salts. Hope this helps!
Answer::Democritus
Explanation
The idea that all matter is made up of tiny, indivisible particles, or atoms, is believed to have originated with the Greek philosopher Leucippus of Miletus and his student Democritus of Abdera in the 5th century B.C. (The word atom comes from the Greek word atomos, which means “indivisible.”) These thinkers held that,
