Atomic Theory Scientist

Question 1

what did John Dalton discover

Answer 1

the atom (like billiard balls)

that matter is composed of indivisible atoms which are identical for each atom

Question 2

what were the problems with John Dalton’s discovery

Answer 2

(discovered the atom)
Problem:
-atoms can be divided into protons,neutrons, and electrons
-different isotopes exist

Question 3

what did JJ Thomson discover

Answer 3

electrons and that atoms are like a raisin bun
–> e- are raisins in positive dough
-that they’re embedded in a positively charged space

Question 4

what were problems in JJ Thompson’s discovery

Answer 4

Discovery: Electrons
Problems:
-atoms have a positively charged core

Question 5

what did Robert Millikan discover and how

Answer 5

the mass of electrons
*calculated using oil droplets between charged plates

Question 6

what did Ernest Rutherford discover and how

Answer 6

-protons and positively charged nucleus
-gold foil experiment

Question 7

what were the problems (3) with Ernest Rutherford discovery

Answer 7

Discovery: protons and positively charged nucleus
Problems:
-nucleus composed of +ve charges should repel apart
-couldn’t explain total mass
-atoms are stable

Question 8

what did Mark Planck discovery

Answer 8

energy is quantized
-energy is not continuous but comes in “bundles” called quanta

ex: Stairs are quantized but ramp is continuous

Question 9

What did Einstein discover and how is it found

Answer 9

Photoelectric effect
-light is made up of bundles of energy called photons

Found using E=hf

Question 10

where is visible light located on the electromagnetic spectrum

Answer 10

-between ultraviolet and infrared

Question 11

what did Niels Bohr discover & explanation

Answer 11

electrons move in stable orbits around the nucleus but can change energy levels

-if e- move to a higher state they’re excited
-if they fall to a lower level they give off energy
-the amount of energy gained/lost must be equal to the energy difference between the two orbits

Question 12

problems with bohr’s theory

Answer 12

-electrons do not simply travel in circular orbits
-couldn’t explain the emission spectrum of H and other 1e- ions

Question 13

what did James Chadwick discover and what’s a key point

Answer 13

neutrons
-mass of the nucleus is made up of protons and neutrons
*Different isotopes have different numbers of neutrons