Atomic structure

Question 1

Atomic timeline - 1803.

Answer 1

Dalton - solid atom model: all atoms of an element are identical; different elements have different atoms.

Question 2

Atomic timeline - 1897.

Answer 2

Thomson - discovers the electron.

Question 3

Atomic timeline - 1904

Answer 3

Thomson - plum pudding model: atoms are spheres of positive charge with negative electrons dotted around the inside.

Question 4

Atomic timeline - 1911.

Answer 4

Rutherford - solar system model: atoms have a positive nucleus surrounded by negative electrons in orbits.

Question 5

Atomic timeline - 1913.

Answer 5

Bohr - electron shell model: electrons occupy shells or energy levels around the nucleus.

Question 6

Atomic timeline - 1918.

Answer 6

Rutherford - discovers the proton.

Question 7

Atomic timeline - 1932.

Answer 7

Chadwick - discovers the neutron.

Question 8

Describe the structure of an atom.

Answer 8

Central nucleus containing protons and (usually) neutrons surrounded by electrons in shells.

Question 9

Explain why atoms are electrically neutral overall.

Answer 9

Atoms contain equal numbers of protons and electrons. Protons have a +1 charge, and electrons have -1 charge, so charges can be cancelled out.