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Chemistry > 3.1 The History of the Atom > Flashcards

3.1 The History of the Atom Flashcards

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1
Q

What did Democritus discover?

A

he discovered the concept of the atom and predicted that matter is composed of elementary particles

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2
Q

How long did it take for scientists to confirm Democritus’ theory?

A

2000 years

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3
Q

Who was the first to apply stoichiometry?

A

Lavoisier

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4
Q

What is Lavoisier also known as?

A

“Father of Modern Chemistry”

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5
Q

Who created the modern atomic theory in 1807?

A

John Dalton

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6
Q

What was stated in John Dalton’s atomic theory?

A

Elements consists of atoms
Atoms cannot be created divided or destroyed
Atoms of the same element have identical properties (like size and mass)

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7
Q

What did J.J Thomson discover?

A

The electron and the mass to charge ratio of electrons

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8
Q

What device did J.J Thomson use to discover the electron?

A

The cathode ray

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9
Q

Who is associated with the “plum-pudding”/“raisin bun model”?

A

J.J Thomson

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10
Q

Due to the fact that electrons could be generated using different metals as the electrodes means…

A

All atoms must contain electrons

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11
Q

Since atoms are neutral they must contain…

A

A positive charge

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12
Q

Who conducted the charged oil experiment?

A

Robert Millikan

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13
Q

What was the outcome of the charged oil experiment?

A

Could slow the drops of oil by adjusting voltage

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14
Q

What did Robert Millikan determine?

A

The mass of the electron

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15
Q

What did Henri Becquerel discover?

A

That uranium could produce an image on a photogenic plate IN THE ABSENCE OF LIGHT

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16
Q

What did Becquerel conclude about Uranium?

A

Uranium atoms must spontaneously emit radiation

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17
Q

What is radioactivity?

A

The spontaneous decay of the nucleus of an atom

18
Q

What did Ernest Rutherford discover?

A

The alpha particle (which is essentially the helium atom)

19
Q

What else did Ernest Rutherford name?

A

The beta particle and the gamma ray

20
Q

What is the gold foil experiment?

A

Fired alpha particles at a thin sheet of gold foil

21
Q

What was the outcome and conclusions of the gold foil experiment?

A

MOST alpha particles passed through meaning atoms are mostly empty space
SOME alpha particles were scattered meaning there is a concentrated positive charge at the centre of the atom

22
Q

What was wrong with the gold foil experiment?

A

The observations did not support Thomson’s model

23
Q

What did Rutherford name positive charges as?

A

Protons

24
Q

Who is James Chadwick?

A

He worked with Rutherford to measure the mass of different nuclei

25
Q

What did Chadwick notice about the mass of the nuclei?

A

The mass of the nuclei was greater than the mass of the protons
Also reasoned that the nucleus also contains uncharged particles called NEUTRONS

26
Q

What are isotopes?

A

Are atoms that have equal numbers of protons but different numbers of neutrons

27
Q

What are radioisotopes?

A

Unstable isotopes, their additional neutrons decay and release radiation

28
Q

What is the particle theory of light?

A

Light exists as a stream of light

Proposed by Greek philosophers in 300 BC

29
Q

Who created the wave theory of light?

A

Christiaan Huygens

30
Q

What is the wave theory of light?

A

Light exists as a wave

Supported by experiments on reflection, refraction and diffusion of light

31
Q

What theory fid Newton defend

A

The particle theory

Light is made up of tiny particles called corpuscles

32
Q

What did James Clerk Maxwell publish?

A

A Dynamical Theory of the Electromagnetic Field

33
Q

What is electromagnetism?

A

Light is on electromagnetic wave made of electric and magnetic fields, explaining how light could have an effect on charged particles

34
Q

Who first discovered the photoelectric effect?

A

Hertz

35
Q

What is the photoelectric effect?

A

a light shining on a metal surface (any surface) causes emissions of electrons from the metal/object

36
Q

What determines the energy of the electrons emitted from a substance?

A

Frequency

37
Q

What is the THRESHOLD FREQUENCY?

A

The minimum frequency required to emit an electron

38
Q

What are blackbodies?

A

Objects that can be heated to incandescence, perfect emitters and absorbers, do not reflect light

39
Q

Who worked with blackbodies?

A

Max Planck

40
Q

What does the Classical Theory (Rayleigh-Jeans Law) predict?

A

Increasing temperature will result in objects emitting infinitely high intensity UV light

41
Q

What did Planck conclude about energy?

A

Energy must be quantized (gained or lost in very small packets) NOT as a continuous wave

Chemistry (3 decks)

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