In the development of atomic theory and the discovery of new elements, who first identified the element radium?

In atomic theory, the electron cloud model describes electrons as existing in regions of probability rather than fixed orbits. Who is most closely associated with developing this electron cloud (quantum mechanical) model?

In atomic theory, the electron cloud (quantum mechanical) model describes electrons as existing in probability distributions rather than fixed orbits. Who is most closely associated with developing this model?

In atomic theory, who is most commonly credited with developing the quantum mechanical (electron cloud) model of the atom?

In atomic theory, who is most commonly credited with developing the electron cloud (quantum mechanical) model of the atom?

In the development of atomic theory, who hypothesized that atoms are tiny, hard, indivisible spheres?

In atomic theory, how did Henry Moseley organize the periodic table compared with earlier arrangements?

In Mendeleev's first widely accepted periodic table, how were the elements primarily arranged?