Atomic Models and Theories

Daltons atomic theory suggests

1) Atoms is made up of tiny particles called atoms

2) Atoms of different elements are different

3) Atoms of the same element are identical

4) Atoms are indivisible and indestructible 

Which 2 dalton theories were modified

Atoms of the same element are identical and atoms are indivisible and indestructible

why is “Atoms of the same element are identicle” incorrect?

Not true due to the discovery of isotopes 

why is “atoms are indivisible and indestructible” wrong?

this was modified due to the discovery of subatomic particles and the development of the nuclear bomb  

Thompson Model is based on

the results from his cathode ray experiment

based on the results of the cathode ray experiment Thompson suggested

the atom is a solid positive mass with negative electrons embedded

Rutherford model was proposed based on the results of his

Gold Foil Experiment

Why was the Rutherford experiment conducted

to prove that the Thompson model was correct 

What occurs in the Rutherford experiment

he filled alpha particles (α particles) at gold foil

an alpha particle is equivalent to the 

helium nucleus 

What happened when Rutherford expected all of the alpha particles to go through the foil

Instead most went through, some came directly back and some deflected to the sides

Rutherford after the gold foil experiment proposed that the atom is comprised of

small dense positivly charged nucleus surrounded by predominantly empty space. 

Which was the first planetary model?

The Rutherford model

What is the problems with the rutherford model?

This model does not explain why the electrons as they lose energy do not crash into the nucleus

Bohr Model according to this model the nucleus is surrounded by

shells (orbits)

The closer the shell is to the nucleus

the lower the energy

The shells were designated

K L M N

Bohr suggested that the energy of the shells is 

quantized 

quantized energy is energy in

discrete bundles of fixed amount (packaged energy)

The scientist responsible for the concept of quantized energy is

Max Planck

An electron could move from shell to shell by

absorbing or releasing energy 

To go from a low energy shell to a high energy shell

energy is absorbed

To go from a high energy shell to a low energy shell

energy is released

What is the first problems of the Bohr Model?

The model attempts to map the path of an electron which cannot be done.

What is the secound problem of the Bohr Model?

The model works “OK” for hydrogen because hydrogen has one electron. However, it couldn’t explain the spectra obtained for multi-electron atoms