History of the atom Flashcards
What was Dalton’s discovery about the atom and what year did he discover this?
He found that elements react in the same mass ratios to form a given compound, and devised the concept of indivisible atoms to explain this. He discovered this in the 1800s.
What did Thomson discover and in what year?
The electron in 1897. The plum-pudding model was then established.
What did Milliken discover and in what year?
In 1909 he discovered the charge on the electron.
What did Rutherford find and in what year?
In 1909 he did the gold-foil experiment, leading to the discovery of the nucleus. He proposed the planetary model of the atom in 1911.
What did Chadwick do and in what year?
He discovered the Neutron in 1932.
What did Planck propose and in which year did he do this?
In 1900 he suggested that EM radiation could only be absorbed or emitted in quanta (discrete packets with energy stored in them). These quanta are more frequently referred to as photons.
What did Einstein propose and in what year?
In 1905 he suggested that light was made up of photons, which could explain the photoelectric effect.
What did Bohr propose and in what year?
In 1913 he proposed a new model of the atom, with the idea that electrons travel in circular orbits around the nucleus, held by attractive electrostatic forces within the nucleus.
What were success of the Bohr model?
Worked well for hydrogen, explained the Rydberg formula for the emission lines of the hydrogen spectrum, introduced quantum numbers and quantisation.
What were failures of the Bohr model?
Useless for anything apart from hydrogen, didn’t explain why only certain orbits were allowed.
What did de Broglie propose and in what year?
In 1924 he proposed that all matter had wave-like properties.
What was the Davisson-Germer experiment?
In 1925 they shone an electron beam at a nickel crystal and recorded the pattern. A pattern of light and dark was found (constructive/destructive waves). This is called a diffraction pattern.
