History Of The Atom Flashcards
What did John Dalton do?
Atoms were first described as solid spheres but there are different
(Discovery of elements)
What did JJ Thomson do?
Plum Pudding Model. That the atom is a ball of charge with electrons embedded in them
What did Ernest Rutherfod discover?
The most mass is at the center of the atom most of it is empty space as most of the atoms passed straight through.
The nucleus has a positive charged as some electrons were reflected straight back
Most of the mass is in the middle of the atom as occasionaly some particles got reflected back to sender
How did Ernest Rutherfod discover what he did?
The Alpha scattering experiment.
He fired a beam of alpha particles through a thin gold foil.
Many went straight through but some was deflected a bit and a few were deflected straight back.
This showed that showed that most of the mass must be at the middle (the nucleus) also that the nucleus must be positivly charged
What did Nieles Bohr discover?
The electrons orbit at different energy levels around the nucleus
When did Niels Bohr discover what he did?
1911
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When did John Dalton discover what he did?
1804
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When did JJ Thomson discover what he did?
1897
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When did Ernest Rutherfod discover what he did?
1909
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When did James Chadwick discover what he did?
1932
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What did James Chadwick discover?
There are neutrons in the nucleus. This explained the differences in the Atomic mass number and mass numbers.
About 20 years after the nucleus was accepted
What are the charges of the poton, neutron and electron?
Proton = +1 Neutron = 0 Electron = -1
What is the radius of an atom?
1X10^-10Meters
What is the radius of the Nucleus?
1X10^-15Meters
How may an atom gain energy?
By absorbing EM radiation they move to a higher energy level
By releasing energy they move closer to the Nucleus
What is the atomic number?
The amount of protons
What is the mass number?
The amount of protons + neutrons
Who first described an atom?
Democtrius
What did Democtrius believe?
An atom was the smallest amount of matter that there was and that they were a solid sphere which couldn’t be divided to be any smaller
What did JJ Thompson use to discover what he did?
Cathod rays which were used to fire electrons (eg in TV’s)
Whata re the differences and similaritys between JJ Thompson and Rutherfod’s models?
JJ Thompson
No nucleus
Electrons were inbeded in the atom
Rutherfod
A densly charged positive nucleus
Both
There shaoe is spherical
They contain sub atomic particles
They have a nuetral charge
How did Bohr discover that electrons orbited the nucleus at different energy levels?
Experiemtns also his calcuations lined up with experimental observations
What could the nucleus be subdivided into?
Whole numbers of smaller particles with the same amount of possitvie charge
This was called the proton
