Chem History Flashcards
What did JJ Thomson Discover in 1897 and how with what experiment?
Also, how did this contribute to the new atomic model?
JJ Thomson discovered the electron using a chathode ray tube to determine the charge to mass ratio.
This discovery introduced the “Plum Pudding” model of the atom. Essentially, this model portrays the atom as a positively charged mecium embedded with these negatively charged subatomic particles.
What did Rutherford discover in 1911?
Also, how did this contribute to the new atomic model?
Rutherford discovered the atomic nucleus, where most of the atom’s mass resides (although only occupying 1/10,000 of the volume).
Instead of the negatively charged particles being embedded in the positively charged medium (Thomson’s atomic model 1897), Rutherford determined that these negatively charged subatomic particles (electrons) were actually orbiting a central, positively charaged mass (the nucleus).
What did Milikan discover in 1909?
Milikan discovered the mass of an electron during the “Oil drop experiment.”
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.
What is the speed of light?
c = 3.00 · 108 m/s
What did Bohr discover in 1913?
Also, how did this contribute to the new atomic model?
Bohr proposed a new atomic model for the hydrogen atom, stating that electrons orbit the nucleus in discrete energy levels (which came to be known as orbitals). Bohr also concluded that electrons can jump (up or down) energy levels, absorbing or emitting electromagnetic radiation.
What did Schrodinger discover in 1917?
Also, how did this contribute to the new atomic model?
Schrodinger published the famous “Schrodinger equation,” which describes the movement of electrons as both a particle and wave. This model became known as the electron cloud, and largely contributes to the atomic model today.
