history of the atom

Question 1

What was Atomic Theory?

Answer 1

The idea that everything was made of tiny particles that cant be broken down any further and that they’re separated by empty space

Question 2

Who originally proposed the idea of Atomic Theory?

Answer 2

Democritus (500BC)

Question 3

What did John Dalton believe?

Answer 3

Dalton drew upon Democritus’ theory. His theory stated that atoms are solid spheres: indivisible, those of a given element are identical, and compounds are combinations of different types of atoms

Question 4

What was wrong about Dalton’s theory?

Answer 4

Atoms aren’t indivisible - they’re composed from subatomic particles

Question 5

What was correct about Dalton’s theory?

Answer 5

• Every single atom of an element, such as gold, is the same as every other atom of that element
• The atoms of one element differ from the atoms of all other elements

Question 6

When did Dalton produce his theory?

Answer 6

1803

Question 7

Who produced the Plum Pudding model?

Answer 7

J.J. Thompson

Question 8

When did J.J. Thompson produce the Plum Pudding model?

Answer 8

1904

Question 9

When did J.J Thompson discover electrons?

Answer 9

1897

Question 10

What was J.J Thompson’s theory?

Answer 10

• Atoms couldn’t be solid spheres
• Atoms must’ve contained negatively charged particles
• Atoms consisted of a ball of positive charge
• Atoms consisted of discrete negatively charged particles (electrons)

Question 11

Who carried out the gold foil experiment?

Answer 11

Ernest Rutherford

Question 12

Describe the gold foil experiment

Answer 12

• Rutherford used a radioactive element (Radium) which naturally decays and emits alpha particles and enclosed it in a container with a tiny opening and so he got a beam of positively charged alpha particles coming through it
• He beamed it onto a thin gold foil surrounded by a detector which was coated in a fluorescent substance that flashed when the alpha particles hit it

Question 13

What was Rutherford results after the gold foil experiment?

Answer 13

• Many particles went straight through the gold foil
• Some bounced back
• Some were deflected at large angles

Question 14

What did Rutherford conclude after the gold foil experiment?

Answer 14

• Atoms are made up of mainly empty space as most particles went straight through
• At the center there’s a region of dense positive charge as some particles bounced back and some deflected

Question 15

What was correct about Rutherford’s model?

Answer 15

• Positive charge in center: nucleus
• Empty space

Question 16

What was wrong about Rutherford’s theory?

Answer 16

• The electrons surrounding the positively charged center would make the structure collapse

Question 17

What was Rutherford’s atom model called?

Answer 17

The nuclear model

Question 18

When did Rutherford produce his model?

Answer 18

1911

Question 19

What did Niels Bohr discover about the atom?

Answer 19

• Electrons move around the nucleus in orbits of fixed sizes and energies
• They were in shells

Question 20

What did Rutherford later discover after Bohr’s model?

Answer 20

• The positively charged center consisted of small discrete particles (protons)

Question 21

What did James Chadwick do?

Answer 21

• Provided evidence for neutral particles in the center (neutrons)

Question 22

When did Bohr produce his model?

Answer 22

1913

Question 23

When did Schrodinger produce his model?

Answer 23

1926

Question 24

What was Bohr’s model called?

Answer 24

The Planetary Model