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Chem Test #2
Information covered on second exam and likely the final
14
Chemistry
Undergraduate 1
10/16/2007

Additional Chemistry Flashcards

 


 

Cards

Term
Democritus
Definition
believed in indivisible elements he called atoma
Term
Dalton
Definition

         Each element is made of atoms; all atoms of a given element are identical.

          Atoms are indivisible, they cannot be created or destroyed.

         Atoms of one element are different from other elements.  All atoms of one element have the same mass.

         Atoms of one element may combine with atoms of other elements, usually in the ratio of small, whole numbers, to form chemical compounds.

Term
Law of multiple proportions
Definition
When two elements combine, the different weights of one element that combine with the same weight of the other element are in a simple ratio of whole numbers
Term
Aufbau
Definition

  electrons have to go into the lowest energy level first.  When electrons come down it’s known as emission, this is visible by a display of light.

Term

Pauli exclusion principle 

Definition
no two electrons can have the same quantum numbers.
Term

Definition

Electrons occupy all of the orbitals in a given sublevel single before pairing begins.
Term

Thompson

Definition
studied CRT – Cathode Ray Tubes

Known for the plum pudding model, which says that inside the atom there’s a positive charge and electrons orbiting the nucleus have a negative charge.

-He measured the degree of deflections of cathode rays by electrical fields of different magnitudes.  He showed that when the cathode rays are deflected by a magnetic field, as indicated by the change in position of the luminescence they produce, the negatively charged particles are correspondingly deflected.

-He came up with the ratio of an electrons mass to its charge.

Term

Millikan

Definition
“Oil drop experiment”

          He was able to calculate the mass and the charge of an electron.


He has an electric charge plate that he was looking at through a microscope.  He sprayed oil droplets onto the plates and noticed that they were coming down bc of gravity.  Then he connected it to a battery, so the plates were charged, then the droplets became suspended in air.  Because of the suspension he was able to calculate the mass and charge.

 

Term
        S
Definition
  Coined the word electron
Term
Goldstein 
Definition
Discovered the proton (which has a positive charge
Term
Chadwick
Definition
Discovered the neutron (which has a neutral charge).
Term

Ernest Rutherford

Definition
= Gold- foil experiment

He took a piece of gold foil and bombared it with alpha particles [also known as He or Hellium particles] (positive charge) and they went straight through the foil but not at the nucleus because it’s positively charged and same charged particles repell. ….nucleus is positively charged and dense.

            Nucleus – protons and neutrons

Term

Quantum theory & Bohr  

Definition
He said electrons travel outside the nucleus, which is known as the Planetary Model

                First electron level carries 2, second 8, third 8, fourth 16, etc.

 -          He explained the energy levels as quantized. 

-          E.g. You have stairs, lets say you can skip two steps, this is the opposite of quantized.  With electrons they cannot skips steps, they have to go through each level, and they need energy to pass through each level.

-          N =  1 à 5 (N means Energy) it is the principle quantum #

o       N = 1 is the ground state and lowest energy level, the electron can get no closer to the  proton

o       The lower the energy, the more stable the atom

o       When an electron is in a higher (less negative) energy orbit (i.e. n=2 or higher) the atom is said to be in an excited state

o       Energy must be absorbed for an electron to move to a higher state (one with a higher n value)

o       Energy is emitted when the electron moves to an orbit of lower energy (one with a lower n value)

 

-          How do fireworks operate?  Light is the source of the explosion, everything goes up you see light (or energy) and sound (another form of energy).   Certain elements turn colors when heated ….copper turns green, potassium turns to light purple, lithium or strontium turns red, sodium turns yellow.

-          Emission = when electron emits or lets off a photon or light. 

§         Fluorescence – Quicker than phosphorescence

§         Phosphorescence  - Slower than fluorescence

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