Models Of Atomic Structure Flashcards

1
Q

What did Democritus say about atoms

A

Everything is made up of atoms which are tiny indivisible particles

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2
Q

Why did Democritus fail to convince anybody that his theory was correct

A

He did not do experiments so had no way to test his theory about atoms

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3
Q

Main points of daltons atomic theory

A

-elements made up of indivisible atoms(atoms of same element are identical with same mass)
-atoms of dif elements have dif masses
-atoms can combine to form molecules in compounds-molecules of compound are identical

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4
Q

What did JJ Thomson discover

A

Discovered electrons which were particles smaller than atoms, knew that atoms had overall no electrical charge so rest of atom must be positive. Created plum pudding model-atoms balls of positive material with electrons embedded in them

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5
Q

Describe Rutherford’s alpha scattering experiment and what did they expect to find

A

Directed narrow beams of alpha particles(knew they were positive) at a very thin gold foil sheet only a few atoms thick.
-expected particles to pass straight through foil or deflected slightly

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6
Q

Results of the alpha scattering experiment and conclusions drawn from these

A

-most alpha went straight through=atoms mainly empty space
-very few alpha deflected by foil=atoms have small positively charged nucleus due to protons where mass of atom is concentrated
-rarely rebounded from foil=some alpha particles approached gold atom nucleus ‘head on’

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7
Q

Describe the model that came as a result of the alpha scattering experiment

A

The nuclear model-very small positive nucleus surrounded by much larger region of empty space in which electrons orbit the nucleus at different energy levels

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8
Q

What did James Chadwick discover

A

Proved that there must be uncharged particles in the nuclei of atoms(neutrons) which helps to explain isotopes and the relative masses of elements (eg helium is 4 not 2 as it has 2 neutrons as well as 2protons)

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9
Q

Oder that subatomic particles were discovered in and by who

A

-electrons by JJ Thomson
-protons by Rutherford
-neutrons by James Chadwick

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10
Q

How many neutrons does hydrogen have

A

None

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11
Q

What is the atomic number of an element and it’s symbol

A

The number of protons in the nucleus of an atom
-symbol= Z

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12
Q

What is the mass number of an element and it’s symbol

A

Total number of protons and neutrons in the nucleus of an atom
-symbol=A

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