Structure Of Atoms

Question 1

Dalton

Answer 1

-all matter is made of tiny particles called
atoms, which cannot be broken down any further.

Question 2

JJ Thomson

Answer 2

discovered electron using cathode rays.
Atoms now made of subatomic particles.

Question 3

Rutherford

Answer 3

found that atoms are mostly empty space
with positive centre following the gold foil experiment.

Question 4

Bohr

Answer 4

electrons in energy levels

Question 5

Rutherford

Answer 5

discovered proton

Question 6

Chadwick

Answer 6

discovered neutron.

Question 7

What does atomic number tell you

Answer 7

• The atomic number tells you how many positive
protons are in an atom.
• It also tells you the number of negative electrons.

Question 8

Atomic number =

Answer 8

Atomic number = number of protons

Question 9

What does mass number tell you?

Answer 9

The mass number tells you the number of
protons + neutrons in the nucleus.

Question 10

Mass number =

Answer 10

Mass number = number of protons +
number of neutrons

Question 11

What are isotopes?

Answer 11

Isotopes are atoms of the same element
with the same number of protons, but a
different number of neutrons.

Question 12

Isotopes and chemical reactions REMEMBER

Answer 12

• Different isotopes of the same element have
the same number of electrons.
• The number of neutrons has no effect on
reactions of an element.
• Different isotopes of an element react in the
same way.

Question 13

What is the relative atomic mass?

Answer 13

Relative atomic mass (Ar) is the mean mass of an
atom of an element compared to carbon – 12.