Chemistry 10-20-09 Structure of the Atom
CHEMISTRY: Hey guys, here’s the lecture from Tuesday on the discovery of electrons and the nucleus. Lots of stuff to learn, but make sure you just don’t learn facts. Check out the videos in the VodPod collection below. You can find the cathode ray tube experiment, Rutherford’s gold foil experiment, and others. Be able to explain not only what they did in their experiments, but how Thompson and Rutherford used the experimental results to discover the electron, nucleus and protons. Hey, you’ll see a little of what they felt like tomorrow. Don’t forget your “atoms.” 
October 21st, 2009 at 9:33 AM
What was used to see the beam when electricity was shot through the cathode ray tube? I know it was a screen of some sort, but what was it made of?
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Annalee S HC4 Reply:
October 21st, 2009 at 3:45 PM
I don’t know about a screen but the tube was coated in a layer of phosphorous.
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October 21st, 2009 at 4:17 PM
In Rutherford’s experiment, were the cathodes positive or negative?
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Buckley Dowdle HC4 Reply:
October 21st, 2009 at 6:07 PM
Cathodes are negative, and anodes are positive. He had an anode at one end and a cathode at the other. The beam was attracted to the positive charge (the anode).
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October 21st, 2009 at 6:58 PM
For the sock lab that we did today can we write on the back of the sheet of paper?
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Ms. Skinner Reply:
October 21st, 2009 at 9:50 PM
Sarah – sure.
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October 21st, 2009 at 11:32 PM
Do the number of electrons equal the number of protons?
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megan filka c1 Reply:
October 22nd, 2009 at 9:24 PM
yes lindsey they do.and take the mass number and subtract the atomic number to get the neutrons.
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Nick A. C7 Reply:
October 22nd, 2009 at 10:38 PM
Also Lindsey, your number of protons is the same number as the atomic number of your element.
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October 22nd, 2009 at 9:27 AM
lindsey- im pretty sure they do.
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October 22nd, 2009 at 9:29 AM
in the gold foil experiment did it take just 1 time to get the experiment right or did it take Retherford multiple times?
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Emily Lunati C1 Reply:
October 22nd, 2009 at 9:58 AM
I don’t think there was a right answer for his experiment, but Rutherford did repeat the experiment multiple times since the positvely charged particles did bounce right back to him, despite his prediction based on his knowledge.
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October 22nd, 2009 at 4:18 PM
lindsey- i think they do too
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October 22nd, 2009 at 5:00 PM
How the scientist figure out the mass of atoms?
i can’t belive they figure out the mass of atoms in their century
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October 22nd, 2009 at 5:14 PM
whats vthe average atomic mass for lithium?
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JeremyCarson Chem2 Reply:
October 22nd, 2009 at 6:06 PM
I think it is 6.9 Not sure
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October 22nd, 2009 at 5:14 PM
whats the average atomic mass number for lithium?
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Chris Norris c-6 Reply:
October 23rd, 2009 at 8:29 AM
Kaitlyn, rounded up, the average atomic mass for lithium is 7.
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October 22nd, 2009 at 5:20 PM
In the cathode how did they get all of the air out?
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Cody Kerby C1 Reply:
October 22nd, 2009 at 5:35 PM
they used a vacuum in the bottom of the tube and sucked all the air until there was none left
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October 22nd, 2009 at 5:59 PM
the average atomic mass for lithium is 7.
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October 22nd, 2009 at 6:13 PM
is atomic mass the mass of the protons plus the mass of the neutrons?
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AVERY PAXTON C1 Reply:
October 22nd, 2009 at 7:38 PM
No Claire the mass number is the number of protons plus the number of neutrons.
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October 22nd, 2009 at 6:31 PM
who were the five scientist that help discover the atom?
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#56 Ryne L. C6 Reply:
October 22nd, 2009 at 7:21 PM
i think it is:
Democritus
John Dalton
Ernest Rutherford
JJ Thompson
Robert Millikan
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October 22nd, 2009 at 6:33 PM
yess the atomic mass is the mass of protons and neutrons.
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October 22nd, 2009 at 6:44 PM
When is the chemistry test?
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Ashley Stallings C-6 Reply:
October 23rd, 2009 at 9:39 AM
The homework sheet says Thursday October 29th.
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October 22nd, 2009 at 7:01 PM
Ms.Skinner, I was wondering what was James Chadwicks experiment when he found Neutrons in the necleus of an atom?
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October 22nd, 2009 at 7:09 PM
what is one of the solutions?
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October 22nd, 2009 at 7:23 PM
How can protons be so much bigger than electrons even though they are neutral? It seems like they wouldn’t be neutral if one is so much bigger than the other?
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caitlin H. c6 Reply:
October 22nd, 2009 at 10:59 PM
thats a good question.
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October 22nd, 2009 at 8:02 PM
Is the atomic number the number of protons?
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Alec M. C7 Reply:
October 23rd, 2009 at 9:34 AM
Yes and if you subtract the mass number and atomic number you get the number of neutrons.
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October 22nd, 2009 at 8:12 PM
The atomic number is the number of protons and electrons
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October 22nd, 2009 at 8:38 PM
in the cathode ray experiment.. what is the line that glows and goes up and down? i mean what does that line show?
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October 22nd, 2009 at 9:11 PM
I’m not positive but I think that it shows that there is an electron in the tube.
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October 22nd, 2009 at 9:32 PM
not just one electron a whole lot of them. and since it moves up and down it means that the electrons are negatively charged because it is attracted to the positive end of the magnet but the negative end of magnet pushes the beam away (because like forces repel)
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Ms. Skinner Reply:
October 23rd, 2009 at 11:52 AM
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October 22nd, 2009 at 9:39 PM
How do you find the number of neutrons in an atom?
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October 22nd, 2009 at 10:24 PM
yes kamren, it is# of protons and electron. neutrons can increase to make in isotope though
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October 22nd, 2009 at 10:57 PM
what did they use to shoot the charges at the gold wire thing?
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October 22nd, 2009 at 11:57 PM
Caitlin they shot alpha particles
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October 23rd, 2009 at 9:40 AM
Someone please remind me, who was the first one to discover the atom?
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October 23rd, 2009 at 9:41 AM
when is the isotope project due?
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Ms. Skinner Reply:
October 23rd, 2009 at 11:33 AM
Emily – great question because I’ve changed the due date! It’s now due on Tuesday, Nov. 3.
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October 23rd, 2009 at 9:43 AM
tori,
John Dalton was the first to discover the atom…
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October 23rd, 2009 at 12:18 PM
Did Lise Meitner get credit for her expirement before or after her death?
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October 23rd, 2009 at 2:29 PM
is the mass number protons plus neutrons?
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October 23rd, 2009 at 4:15 PM
Did Ms.Skinner ever tell anyone about the project we’re gonna have to do?
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Ms. Skinner Reply:
October 23rd, 2009 at 8:08 PM
Hmmmm…. Did you find it on Edline or here on the website under “Chemistry Projects”?
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October 23rd, 2009 at 5:17 PM
Is the mass number the number of protons plus neutrons?
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Brett PolischeckC1 Reply:
October 23rd, 2009 at 6:58 PM
Yes, mass number is protons plus neutrons
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