Evolution of Atomic Theory [Part I]

Plum pudding

And English dessert consisting of moist cake with embedded raisins

Plum-pudding model

The model that suggested that atoms resembled the plum pudding.

Its positively charged matter was the moist cake and the negatively charged matter was raisins.

Sir Joseph John Thompson

An English physicist who suggested the Plum-pudding model.

Cathode Ray Tube

A sealed glass tube that was used by J. J. Thomson to suggest the Plum-pudding model

Hermetically

(Adverb) in a way that is completely airtight

Sealed glass tube

A container that has been hermetically sealed to create an airtight seal

air

Cathode Ray Tube had almost no ___ in it

Two metal electrodes

Very vital components of the Cathode Ray Tube used by J. J. Thomson

Cathode ray

The visible beam that appeared between the two electrodes;

when a high voltage was applied across the electrodes within the Cathode Ray Tube

positive, negative

Cathode Ray was deflected toward the ________ charge and away from the ________ charge

applied magnetic field

In J. J. Thompson’s similar experiment rays were deflected by an ______________________

Measurements of the extent of deflection and the magnetic field strength

Two things that allowed Thomson to calculate the charge to mass ratio of the cathode ray particles.

1897

Year when Cathode Ray Tube was invented

Karl Ferdinand Braun

Inventor of the Cathode Ray Tube

High voltage

(1)

Cathode(-)

(2)

Anode(+)

(3)

Cathode ray

(4)

Charged plates

(5)

Battery

(6)

Magnets

(7)

Scale on outside of glass

(8)

cathode

Cathode ray beam comes from the _______

anode

Cathode beam gets accelerated the _____

Fluorescent scale

A type of scale that glows brightly when light shines on it (especially the UV light)

electron

Cathode ray particle is what we now call an ________

one thousand-times

Electron’s mass is more than __________________ less than that of an atom

1891

Year when the term “electron” was coined

George Stoney

The Irish physicist who coined the term “electron”

Robert Andrew Millikan

American physicist who accurately measured the charge of a single electron

Oil drop experiment

The experiment that was used to measure the elementary charge of an electron

X-rays

The type of light rays that Millikan utilized to electrically charge the microscopic oil droplets.

Friction

________ by the rays made the microscopic oil droplets electrically charged

X-rays to electrically charge the microscopic droplets

(i)

Pinhole

(ii)

Oil sprayed in fine droplets

(iii)

Oil atomizer

(iv)

Telescopic eyepiece

(v)

Charged oil droplet under observation

(vi)

Electrically charged brass plate

(vii)

gravity, slowed, reversed, electric field

Microscopic oil droplets initially fell due to _______, but their downward progress could be ______ or even ________ by an ______________ lower in the apparatus.

1.602×10^-19 C

Charge of a single electron

1kg/1.759×10^11 C

Charge to mass ratio of electrons calculated by J. J. Thomson

(Electron’s elementary charge)*(charge to mass ratio of electrons)

Equation for the mass of electron

9.109×10^-31 kg

Mass of a single electron

1903

Year when the Saturn-like atom model was postulated

Hantaro Nagaoka

The Japanese physicist who postulated the Saturn-like atom model

Ernest Rutherford

A Kiwi physicist who performed a series of experiments using a beam of high speed positively charged alpha particles.

The radioactive decay of radium

Produced the α particles

2

No. of protons in the α particle