C1a- atomic structure and the periodic table

Question 1

pre 1900 (2)

Answer 1

Solid balls that could not be divided

Before the discovery of the electron, John Dalton said these made up the different elements

Question 2

1897 “plum pudding”

Answer 2

A ball of positive charge with negative electrons embedded in it

Question 3

1909 nuclear model

Answer 3

Positively charged nucleus at the center surrounded by the negative electrons

Question 4

1913 Bohr model

Answer 4

Electrons orbit the nucleus at specific distances

Question 5

Rutherford’s scattering experiment (3)

Answer 5

A beam of alpha particles were directed at very thin gold foil
Most passed right through, a few positive alpha particles were deflected by the positive nucleus
A tiny number of particles reflected back from the nucleus

Question 6

mass number

Answer 6

the sum of the protons and neutrons in the nucleus

Question 7

atomic number

Answer 7

the number of protons in the atom

number of electrons= number of protons