atomic structure

Question 1

What happened in 1662 to support the development of the atom?

Answer 1

Robert Boyle proposed that some substances could not be made simpler

Question 2

what happened in 1803 to support the development of the atom?

Answer 2

John Dalton described atoms as solid spheres, and he said different spheres made up the different elements

Question 3

What happened in 1896 to support the development of the atom?

Answer 3

Henri Bacquerel and his discovery of the term ‘radioactivity’ - showing particles could therefore so come from inside the atom

Question 4

what happened in 1897 to support the development of the atom?

Answer 4

J.J Thomson discovered the electron. this showed that the therefore atoms weren’t solid and indivisible. the ‘solid sphere’ ideas had to be changed; the new model was known as the ‘plum pudding model’.

Question 5

What happened in 1909 to support the development of the atom?

Answer 5

Ernst Rutherford discovered the charge and the mass of an atom and how it is concentrated in a tiny central nucleus. the positive nucleus is surrounded by a ‘cloud’ of negative electrons - most of it is empty space in terms of the atom.

Question 6

what did Rutherford do to gather findings?

Answer 6

• Ernst Rutherford and his students Hans Geiger and Ernst Marden conducted their famous golden foils experiment.
• they fired positively charged alpha particles at a very thin sheet of gold.
  the plum pudding model stated how most alpha particles would be slightly deflected by the positive ‘pudding’ that made up most of the atom therefore
• in fact most of the particles passed straight through the gold with a small number being deflected backwards
  the plum pudding model couldn’t be right, so Rutherford developed the nuclear model of the atom.

Question 7

what caused Niels Bohr to establish a new model?

Answer 7

scientists realised that the so electrons in a ‘cloud’ around a nucleus of atoms, as Rutherford described, would quickly spiral downwards into nucleus, causing the atom to therefore collapse

Question 8

what did Niels Bohr propose in his new model?

Answer 8

stated that electrons exist in shells or orbits of fixed energy. when electrons move between the therefore shells, electromagnetic radiation (with fixed energy or frequency) is emitted/absorbed
the Bohr model fitted experimental observations of the radiation emitted and absorbed by the atoms.

Question 9

why was the Bohr model incorrect?

Answer 9

not all electrons in a the shell have the same energy