Atomic Structure Flashcards
What did Dalton prove wrong?
All matter is NOT made up of tiny atoms
All atoms of an element are NOT identical
Atoms CAN be destroyed, created or divided
Who revised Democritus’ theory?
John Dalton
What in Democritus’ theory was true?
Atoms of different elements combine chemically to form compounds
Atoms of 1 element can’t change into a new element
What was JJ Thompson’s experiment?
Cathode ray tube
What did Thompson discover?
The electron
What did Thompson believe about the atom?
There was a big positively charged blob with small negatively charged electrons
“The plum pudding model”
What was Ernest Rutherford’s experiment?
The gold foil experiment
What did Rutherford discover?
Protons and the nucleus
What did Rutherford conclude about the atom?
Mostly empty space where elections move
Contained a tiny, dense and positively charged area (nucleus)
What did James Chadwick discover?
The neutron
What did Niels Bohr discover?
The 7 orbits around the nucleus that contain the electrons
What are isotopes?
Atoms of the same element but with different # of neutrons
Symbols for isotopes-
Potassium - 39
39 K
19
Why is the AMU not a whole number?
Because it is a weighted average of the isotopes
How do you find the AMU?
(% abundance •mass)
100
Add the AMU of each isotope together
