Lectures 4-8; Test Review Flashcards
Exact numbers
numbers that come about from counting. Also relationships from two units.
Measured numbers
numbers obtained from a measuring device.
Calculations with measured numbers;
Multiplication and/or Division, how is the result expressed?
express your answer with the least number of sigfigs present.
Calculations with measured numbers;
Addition and/or Subtraction, how is the result expressed?
express you answer with the least number of decimal places present.
Accuracy
indicates how close a measurement is to true or accepted value.
Precision
a measure of reliability and consistency.
Democritus
philosopher, 2000 years ago in Ancient Greece suggested that matter was made up of tiny, invisible, indestructible, particles called Atomos
Aristotle & Plato
rejected Democritus theories. They said matter was could be infinitely subdivided and that everything is made from combinations of earth, wind, fire, and water.
Antoine Lavoisier
French chemist who gave the 1st experimental evidence for the law of conservation of matter, which states matter can neither be created or destroyed.
Joseph Proust
worked on the problem of determining the composition of compounds. Created the law of definite proportions which states pure chemical compounds always contain the same proportion (or percent) by mass of each element making up the compound.
John Dalton
Created Dalton’s Atomic Theory and his law of multiple proportions which states the same elements can combine at different proportions to create different pure compounds. His atomic model was a sphere.
J.J. Thompson
discovered 1st subatomic particle, electron (negative charge). Proposed the plum pudding model of an atom.
Eugen Goldstein
discovered the 2nd subatomic particle called the proton (positive charge).
James Chadwick
discovered the 3rd subatomic particle called the neutron (neutral charge).
Ernest Rutherford
showed that atoms are not solid spheres, in his Golf Foil Experiment.
