models of atomic ❌ have changed slightly over the years...
in the start of the ❌ century, ❌ described atoms as ❌... he said that these ❌ made up different elements.
in ❌, ❌ discovered the ❌. this showed that atoms couldn't be solid spheres and indivisible. the new model was known as the ❌.

in ❌, ❌ and his students conducted the ❌ where they fired ❌ particles at a very thin ❌ sheet. the plum pudding model suggested that ❌ alpha particles would be slightly ❌ however most particles passed straight through with only a few being deflected. this showed that the plum pudding model was ❌. ❌ developed the ❌. this showed a tiny ❌ nucleus, surrounded by a ❌ of negative electrons, with most being ❌.
scientists realised that if electrons where in a cloud then they would ❌ down and cause the atom to ❌. ❌ proposed a new model where electrons exist in shells or orbits of ❌. when electrons move between shells, ❌ is absorbed or emitted. this model fitted experimental observations.
this model is still used even though we can refine it into ❌ as this model is simple and easy to understand.

put the scientists in order with their year and experiment...
❌ ❌ in ❌.
❌ ❌ in ❌
❌ ❌ of ❌.
scientists later refined this to have ❌.