Academic Chemistry
Name: _______________________________
DVD – Smaller Than the Smallest
Block/Day: ___________________________
27 Points
Date: ________________________________
Dalton fell backwards through the door that led to his _________________ ____________ Theory.
He was actually looking for the answer as to why water absorbed more of one gas than another.
He decided that when water absorbed a gas, particles of the gas must fit into ____________ or
___________ between the particles of the water. Why does water absorb more than one gas
and less than another? Dalton thought one type of gas particles was ____________, so relatively
few would squeeze between the water particles. With another kind of gas, heavier particles
would sink in greater _______________ between the pores in the water.
Dalton’s theory implied that matter was made of _______________ ______________, with spaces
in between.
Dalton concluded that

Elements of matter consist of characteristic particles.

The particles or atoms of an element are _____________________ to each other.

Atoms are indivisible.

There are as many kinds of ______________ as there are elements.

The atoms of one element cannot be converted into the atoms of another element.
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
Atoms in chemical reactions are not created nor destroyed they are just
__________________________.
Dalton suggested a way of explaining Proust’s _______ ______
______________________
___________________. If each atom is a particular type of element, then these elements
combine in fixed numbers to form what Dalton called compound atoms.
Dalton extended this thinking into his ________ ____
__________________
_______________________, which described how different compound atoms could be formed by
two basic elements. The simplest possible formula is one atom of each kind. Next simplest is
one of one kind and ___________ of another.
After Dalton, the pace of discovery quickened. Faraday used _________________ to decompose
water into hydrogen and oxygen. He decided that electricity was the force of affinity that held
compounds together. Faraday had found the ___________ that held Dalton’s atoms together.
In another experiment, Faraday started with a ___________________ apparatus, to which he
connected a glass tube. When he partially evacuated the air from the tube he saw pink
streamers of light flowing between the terminals.
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Over the years they were able to improve their ability to reduce the pressure in the discharge
tube. Patterns of light changed as the pressure was reduced, until at a near vacuum the tube
had an eerie __________________ _____________.
William Crooks designed more complex vacuum tubes and showed that whatever cause the
glow streamed from the ______________ or negative terminal. By interrupting this stream he
showed it travelled in straight lines. The stream also caused an increase in temperature of
objects in its path. And it also exerted a mechanical force or push. Crooks guessed these
cathode rays were a stream of ____________________________.
J.J. Thompson designed a specialized cathode ray tube. Cathode rays travel between charged
diaphragms to focus the rays in a straight line to strike a fluorescent screen. Charged plates on
either side of the tube deflected the particles toward the _______________ plate. Thompson
concluded that cathode rays consisted of negatively charged particles. Magnetic plates also
bent the cathode rays.
By balancing the deflections of the __________________ and ______________ fields he was able
to calculate the charge to mass ratio. This ratio was 1.76 x 1011 Coulombs/kilogram. This ratio
was independent of the metals in the terminals and also independent of the traces of gases in
the near vacuum. It appeared these cathode rays were _______________________ particles and
were christened electrons. Is it possible that the atom is composed of something still smaller?
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R.A. Millikan established that all electrons are identical by determining their minimum
_____________. Millikan used oil droplets falling through a pinhole. He determined the droplets
rate of fall due to gravity. He then applied a known electrical charge above and below the falling
droplets. This changed the ___________ ___ ___________ of the droplets because they
carried a charge. He then changed the charge on the oil drop by passing X-rays through the
droplets, liberating electrons. When a free electron attached to a droplet the charge changed
and the rate of fall _______________. He found the smallest discrete rate of change and decided
that represented the charge on one electron.
J.J. Thompson provided the raisin bun model to explain why the atoms were neutral. He placed
the negative electrons (raisins) in ___________ dough. Although his model had thousands of
raisins, experiments showed that atoms at most had about 100 electrons.
Back in the kitchen, ________________________was preparing a more satisfying model.
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