atomic structure

Question 1

who was DEMOCRITUS

Answer 1

greek philosopher

first suggested that everything was made of atoms

this idea wasn’t initially accepted

Question 2

who was JOHN DALTON

Answer 2

developed DEMOCRITUS’s ideas

based his ideas on experiments which measured masses of substances before and after a chemical reaction

early 1800s

Question 3

what were JOHN DALTON’S ideas?

Answer 3

-matter is composed of atoms

-atoms of one element have the same size, shape and weight

• during chemical changes, atoms of different elements unite without being changed or broken down

Question 4

who was J. J THOMPSON

Answer 4

late 1800s

passed electricity through low pressure gas
discovered electrons must come from inside atoms

Question 5

who was RUTHERFORD-GEIGER-MARSDEN?

Answer 5

concluded that protons were in a very small nucleus

1911

Question 6

who was JAMES CHADWICK

Answer 6

1932

confirmed the existence of the neutron

Question 7

relative mass of proton

Answer 7

1

Question 8

relative mass of neutron

Answer 8

1

Question 9

relative mass of electron

Answer 9

1/1860

Question 10

relative charge of proton

Answer 10

+1

Question 11

relative charge of neutron

Answer 11

0

Question 12

relative charge of electron

Answer 12

-1

Question 13

23
Na
11

which is the mass number?

Answer 13

23

Question 14

23
Na
11

what is the proton number

Answer 14

11

Question 15

no of protons

Answer 15

atomic number

Question 16

no of electrons

Answer 16

no of protons in the nucleus

Question 17

no of neutrons

Answer 17

mass no - atomic number

Question 18

what is an isotope

Answer 18

atoms of the same element with the same number of protons and electrons but DIFFERENT NUMBERS OF NEUTRONS

Question 19

how is the relative atomic mass calculated?

Answer 19

mass number x percentage of element
———————————-
100

Question 20

how are electrons arranged?

Answer 20

shells

2.8.8