Chem History Flashcards
What did JJ Thomson Discover in 1897 and how with what experiment?
JJ Thomson discovered the electron using a chathode ray tube to determine the charge to mass ratio.
What did Rutherford discover in 1911?
Rutherford discovered the atomic nucleus, where most of the atom’s mass resides (although only occupying 1/10,000 of the volume).
What did Milikan discover in 1909?
Milikan discovered the mass of an electron during the “Oil drop experiment.”
Who was attributed to first describing black body radiation?
Planck first described black body radiation in 1900
What is the formula for the energy of a photon?
E = hν
Where,
E = the energy of a photon
h = Planck’s constant
ν = frequency
In electromagnetic radiation, what is the energy of the radiation directly proportional to?
The energy of electromagnetic radiation is directly proportional to its frequency. This relationship is illustrated by:
E = hv
E = The energy of a photon
h = Planck’s constant
v = frequency
So that as frequency increases, the energy increases.
What is the photoelectric effect?
When a metal is exposed to light, electrons are emitted from the metal.
List the different types of electromagnetic radiation from lowest energy to highest energy (lowest to highest frequency).
Radio Waves < Microwaves < Infrared (IR) < Visible light < Ultraviolet < X-rays < gamma (ᵧ) rays
How does radio wave electromagnetic radiation effect an atom?
Radio waves can cause the protons in the nucleus to flip spin when in a magnetic field - i.e. nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).
What happens when an x-ray or **ᵧ-ray **interacts with the electron cloud of an atom?
At a given frequency, an electron can be emitted from the atom when an x-ray or ᵧ-ray strikes it.
How does infrared (IR) electromagnetic radiation interact with a molecule?
IR radiation causes the bonds in a molecule to vibrate at a given frequency that is measurable by spectroscopic means.
How does ultraviolet (UV) electromagnetic radiation interact with an atom?
When an atom absorbs UV radiation, electrons can jump to a higher quantum state (higher energy) and even be ejected from the atom given sufficient energy.
How does microwave electromagnetic radiation interact with an atom?
Microwaves can cause electrons to flip their spin state when the atom is in a magnetic field - i.e. electron paramagnetic resonance (EPR).
What is Planck’s constant?
h = 6.63 · 10-34 J·s
What is the unit for frequency?
The Hertz (Hz) which is measured in cycles per second, with one cycle being measured from crest to crest or trough to trough for a mave of given wavelength.
