Chemistry- Physical chem fundamental particles

John Dalton atomic model

Atoms were spherical indivisible units of matter

JJ Thompson Plum pudding model

He discovered atoms were divisible and said the atom was a positively charged cloud with negatively charged electrons embedded in it

Ernest Rutherford nuclear model

• Most of the alpha particles fired went straight through which meant most of the atom is empty space.

• Some particles deflected suggesting most of the atom’s mass was positive and concentrated at the center, as like charges repel.

• Some particles bounced back, suggesting most of the mass was concentrated in a tiny volume at the center.

Bohr’s atomic model

The Bohr model (named after Danish physicist Niels Bohr) of an atom has a small, positively charged central nucleus and electrons orbiting in at specific fixed distances from the nucleus. Electrons are not allowed to orbit in the space between these specific fixed orbits.

Mass and charges of sub atomic particles

• Proton 1 and +ve

• Neutron 1/2000 and NA

• Electron 1 and -ve