Atomic Scientists
Which scientist discovered the electron?
Thomson
What was the name of Thomson's atomic model?
Plum pudding
What does atomic number tell us?
An atom of oxygen has 9 neutrons. Write this in isotope notation.
O-17
Why are atoms neutral?
Same number of protons as electrons
Name two scientists who used alpha-rays
Rutherford, Chadwick
Who proved that Thomson's model was incorrect?
Define mass number
Protons plus neutrons
An element has a mass number of 20 and 9 electrons. Write this in atomic notation.
20
F
9
Which particle traveled straight between the magnetic field?
Neutron
Which scientist fixed the atom instability problem?
Bohr
How many electrons would be present in an "R" shell
128
How can we determine the number of electrons in an atom?
Atomic number
An atom of magnesium has a mass number of 20. Write the electron notation.
2)8)2
What charge does an alpha-ray have?
Which scientist discovered anode rays? How did he know their charge?
Goldstein, they traveled towards the cathode (-) side and made a pink light.
What was the main difference between Bohr's and Chadwick's atomic model?
Chadwick had neutrons in the nucleus
Where can we find mass number on the periodic table?
Trick question! We can't.
K-30
30
K
11
2)8)8)1
What happens when cathode rays collide with the gas atoms?
They make the electron fly away and the gas atom becomes positive
Give two reasons that Dalton was incorrect
Indivisible - atoms can be divided into subatomic particles
Identical - atoms can have different number of neutrons (isotope)
Draw a picture and explain why Rutherford's model was wrong
Electrons spiral towards center = unstable
How do scientists calculate atomic mass?
Weighted average of all the isotopes of that element.
Write any three isotopes of this element in atomic notation: 2)8)18)5
Anything higher than 33
As
33
If the nucleus was large instead of tiny, describe what Rutherford's observations would have been?
Few alpha-rays would go straight, some would deflect, most would bounce back