Chapter 3 Flashcards
Proposed the Modern Atomic theory
Law of multiple proportions
Dalton
World is made up of small particles called atoms and empty space- based on observations
Democritus
Modern Atomic Theory
- All elements are composed of Amal invisible particles called atoms
- Atoms of the same element are identical. Atoms of a different element are different
- Atoms combine in simple whole number ratios to form compounds
- Chemical reactions occur, but atoms are never changed into atoms of another element
Changes- atoms of the same element may be different
Atoms can be divisible
Made modern system of chemical symbols for elements
Berzelius
Using Crookes’ Tube determined
Electrons are negatively charged particles all electrons are identical
Plum pudding model
Thomson
Charge of election -1
Mass of electron 0 amu
Millikan
Discovered canal Rays that led to the development of mass spectrometry
Goldstein
Discovered the proton. Charge of +1 and has a mass of 1 Amy
Wien
Did the gold foil experiment with help of Geiger and Marsden
Rutherford
Gold Foil Experiment
Alpha particles were shot at a thin sheet of gold foil. Most particles went straight through while some were slightly deflected
Conclusion
The atom is mostly empty space
The atom contains a small dense positivly charged core called an nucleus.
Predicted the existence of a neutron
Discovered neutron… No charge mass of 1amu
Worked with Geiger and Rutherford
Chadwick
Mass number
Equal to the # of protons and # of neutrons
Not shown on table
Individual mass
Average atomic mass
A weighted average of the masses of all the isotopes.
On table
Amu is based on what?
C-12
1/12 mass of C-12 atoms is one amu
Mole concept
6.02x10^23
1 mol=C-12=12g=12g/mol
