Atomic History Flashcards
Who created idea of Atoms first?
Democritus, ancient Greece 5BCE, came up with idea that all things were made of indivisible things called atomos (greek for indivisible)
ideas were widely rejected
Who first improved on Democritus’ ideas?
John Dalton, came up with Billiard Ball model
Fromed follwoing theories
1. Everything is made of atoms
2. Atoms of same element r identical and atoms of different elements are different
3. Compounds are complosed of atoms of more than one element (ratio of those elemetns are always whole numbers
4. atoms cant be created or destroyed, only rearragned, combined or seperated
wHAT IS Proust’s LAW OF DEFINITE PROPORTIONS?
1799
different samples of same compound always has same proportions
Law of Multiple PropORTIONS?
If 2 elements can form more than one compound than the masses f element that combine with fixes masses of the other eleemtn will alweays be in small whole numbers
What is the law of conservation of mass?
in a chemical or physical change matter cant be created, destoryed, lost or gained
What did JJ Thomson do?
Create plum pudding model
observed negative particles in cathode rays were electrons
What did Wilhelm Rontegen discover?
discovered x-ray
What did Antoine Becquerel discover?
discovered radioactivity but marie Curie named it
What are Alpha particles?
repelled by negatively charged plate
large, positively changed (2 protn + 2 neutrons0
What are beta particles?
repelled by positively changed plate
small, negatively charged (1 high energy electron)
What are gamma rays
not affect by charged plates
high energy rays
What dud Ernest Rutherford do?
USED GOLD FOIL TO SEE HOW ALPHA PARTICLES PASSED IN SOME PARTS AND WERE DEFLECTED IN OTHER PARTS = SOMETHING IN ATOM THAT WAS DENSE AND POSITIVE
discovered nucleus and protons
nuclear model (big bang theory model)
What did Niels Bohr do?
create bohr planetary model in which electron orbit nucleus like planets orbit sun
