chem unit 4 Flashcards
early thinker believed that matter was made out of
water, fire, earth, air
democritus
- believed that matter was made of tiny particles called atomos
-believed that matter was composed of empty space
Aristotle
didn’t not believe that atoms were made of empty space
John Dalton atomic theory
1) matter is composed of extremely small particles called atoms
2) atoms are invisible and indestructible
3)atoms of a given element are identical in size mass, chemical properties
4) atoms of a specific element are different from those of another
5)atoms of a specific element combine in simple whole-number ratios
6) In chemical reaction, atoms are separated, combined, rearranged
what 2 things are wrong with Daltons theory
1) atoms being indivisible to the eye
2) atoms of a given element have the same properties
Sir william Crooks
- ## invented the Cathode ray tube
JJ Thompson
- using the Cathode Ray tube he determined the charge-to-mass ratio of an electron
-responsible for the plum pudding model
Robert Millikan
-know for the Oil-drop experiment
- found the charge of an electron
- using info from Charge-mass- the ratio of electrons he calculates the mass
Ernest Rutherford
-gold foil experiment
- this experiment disproves the Thompson model (plum pudding model)
- developed his own model composed of empty space and a dense core called the nucleus
-atomic model
Radioactivity
the spontaneous emitting of radiation
radiation
the rays or particles emitted
Nuclear Radiation
-a reaction that involves a change in the nucleus of an atom
-a nuclear change is different from a physical change from a chemical change
-in a nuclear reaction, both atomic number and mass number are conserved.
low energy means
that something is more stable
why do nuclear reaction occur
unstable nuclei lose energy by stable emitting in nuclear decay (a spontaneous nuclear reaction)
types of radiation
Alpha, beta, Gamma
