chem history

Question 1

JJ Thomson

Answer 1

1897-discovers the electron using cathode ray tubes (CRTs) while finding the charge to mass ration for the electrons

Question 2

Millikan

Answer 2

1909-Oil drop experiment- determines the electron charge of the electron and using Thomson’s ratio to find the mass of the electron

Question 3

Rutherford

Answer 3

1911-discovers the nucleus, where most of the mass of the atom resides. Nucleus is 1/10,000 the size of the atom

Question 4

how does the cathode ray tube (CRT) work?

Answer 4

Electrons (positive) flow from an energy source to the cathode and jump towards the anode through the space between the two electrodes which is empty (vacuum) or only has a very small amount of gas (Ne, for example)

Question 5

frequency (v) units

Answer 5

(1cycle per second) 1/s =Hz (1 hertz)

Question 6

Wavelength units

Answer 6

lambda m, nm (nanometer)

Question 7

speed of light (c) units

Answer 7

c= lambda v = 3.00x10^8 m/s

Question 8

Planck

Answer 8

1900-explained black body radiation by suggesting that light can exhibit particle like behavior and travels in set amounts of energy packets (protons)
E = h v
h= 6.63x10^-34 (Planck’s constant)

Question 9

Rydberg’s formula

Answer 9

Gas charge lamps and spectra
E= RvH (1/nv1^2 - 1/nv2^2)
RvH= 2.18 x 10^-18 J

Question 10

Bohr’s model

Answer 10

proposed that electrons orbited the nucleus like planets around the sun
Evn = -RvH/n^2 n= 1,2,3,…
Ev4 - Ev3 = -RvH (1/4^2 - 1/3^2)

Question 11

De Broglie

Answer 11

1924- demonstrated mathematically that particles can have wave like behavior
lambda(wavelength) = h/m v
mass(kg) and v= speed (m/s)

Question 12

Heisenberg’s Uncertainty Principle

Answer 12

bc electrons have a wave nature, it is impossible to know it’s location and momentum precisely. Knowledge of one sacrifices info about the other

Question 13

Schrodinger’s Wavefunction

Answer 13

Used to describe the electron and thus developing the field of quantum mechanics