Explaining The Periodic Table, Protons & Electrons - Chemistry 101
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- Опубликовано: 15 июн 2023
- This video explains how the structure of the atom is directly responsible for the shape of the Periodic Table, and allows scientists to read the personality of each kind of atom due to its position. Protons, electrons, and neutrons explain everything about how an atom works and the making of the periodic table itself.
00:15 Scientists J J Thompson (1897), E Rutherford (1907) and J Chadwich (1932) discovery
00:25 Smaller particles: Positively charged protons and electrically neutral neutrons in the center called nucleus
00:51 The Nucleus
01:23 The atom is mainly empty space
01:46 Henry Moseley (1913) discovered that Atomic Number = Number of Protons
02:32 Number of protons = Number of electrons (in a neutral atom)
03:10 Isotopes
03:25 Atomic Mass Unit AMU
04:30 Neutorns have a big effect on the atomic weight but do not matter much in making chemical bonds
04:50 Electron Shells
05:15 Electrons are like guests in a hotel
06:20 Quantum Jump
06:38 Valence Electrons
07:00 Hydrogen
07:35 Helium
08:15 The Periodic Table
08:22 Lithium
08:52 Beryllium
09:00 Boron
09:17 Carbon
09:23 Nitrogen
09:30 Oxygen
09:35 Fluorine
09:39 Neon
09:55 Third shell
10:00 Sodium
10:30 Magnesium
10:40 Alkaline Earth Metals - the same number of valence electrons
11:53 Period 3
13:20 They can explain almost all of chemistry
13:38 Periodic Table Trends
14:00 Next video URL:
Video transcript:
“
To explain how atoms behave, we need to look inside them.
About a hundred years ago scientists discovered that atoms aren’t like tiny solid marbles as they thought, but made of three much, much smaller particles - positively charged protons and electrically neutral neutrons in their centre, called the nucleus, and negatively charged electrons orbiting on the outside in shells. See our video about how scientists discovered protons, electrons and neutrons at the link in the descrIption:
• Chemistry Science: Pro...
THE NUCLEUS
The nucleus is much smaller than shown here in the diagram. If an atom were the size of a football stadium, then its nucleus would be the size of a pea. This means the atom is mostly empty space. And so are YOU.
Even though the nucleus is tiny, it makes up over 99.9% of the atom’s mass. That’s because protons and neutrons are 2 thousand times heavier than electrons. So they don’t matter much.
In 1913, Henry Moseley discovered that an element’s Atomic Number was always the same as the number of protons in its nucleus. What a coincidence! This is now the modern definition of Atomic Number.
This atom has 5 protons so its Atomic Number is 5. This is the number above the element’s symbol on the PT. Which element is it? …. Boron.
In an electrically neutral atom, the number of positive Protons must equal the number of negative electrons so that their charges cancel. So a boron also has 5 electrons. The job of neutrons is to overcome the proton-proton repulsions, and to keep the nucleus together. Most boron atoms use 6 neutrons to stabilize their nuclei, but some can get away with 5. The number of neutrons can vary between atoms of the same kind, so scientists give these a special name- isotopes. So boron has two! isotopes.
Protons and neutrons both have a mass of about 1 atomic mass unit, or amu, or just u, or even the Dalton. They all mean the same thing, which is a bit annoying. Call me old fashioned, but I prefer amu. Scientists use this tiny mass unit for atoms as grams or pounds are too big. Electrons weigh hardly anything. So the atom’s mass is just the sum of its protons and neutrons. Both boron's have 5 protons, so its 6-neutron isotope would weigh 11, and its 5-neutron isotope 10 amu. It’s Atomic Weight shown on the PT is 10.8 and is the average of its two isotopes. It’s is closer to 11 because it’s the more abundant one.
Neutrons have a big effect on Atomic Weight, but don’t matter much in making chemical bonds, which we’re interested in here. So we’ll just look at protons and electrons from now on. Bye, bye neutrons. And Atomic Weights.
ELECTRON SHELLS
The first electron shell can accommodate 2 electrons before it’s full, while the 2nd shell can accommodate up to 8. This is why boron has only 2 electrons in its 1st shell, and the remaining 3 electrons in the 2nd shell.
Electrons are like guests in a hotel. Here’s a normal hotel. And here’s the Quantum Hotel that better shows how electrons fit around an atom. The 1st floor can take 2 guests before it’s full, the 2nd floor also 8, the 3rd floor 8, and the 4th and 5th 18 each. When a floor is full a new arrival is sent to the next floor up. This guest on the 4th floor has more energy than the guests below, which she would find out if she jumped. When she lands, the energy she had turns into sound energy. Electrons in higher levels also have more energy, and when they jump down, light energy is emitted instead. This is called a quantum jump.
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Thanks for your encouragement, Tarit!
this doesn't happen often but i have to give you anbig hug. i actually understand this stuff from your video. your the best
Wow! Hug accepted. Thanks.
Sorry for the late reply. Thanks for your rare hug ... much appreciated.
Wow! I'm sharing this with my college learning center as a resource! Perfect explanation.
What great feedback! Thanks.
P.S. Just to let you know that the video is back up publicly now ... it was down for a while sorting out a copyright issue. It's sorted now.
Your teaching style is excellent.
The way you presented the various atomic concepts is the best I've seen.
Thank you, Rossini!
Perfect video for my young genius; my six year old son really gets off on this stuff 😊
Thanks. I am back in town so hope to keep uploading more.
Fabulous, keep up the good work.
I love your videos! You really break chemistry and these fundamental concepts down in a magical way!
I’m wondering if you could explain what “charge” is? For some reason I just don’t quite understand what it is…
Good question (and sorry for the delay). Charge is like mass in that it is a fundamental property of matter, which is another way of saying that we can't break it down into anything simpler. Things are either positive or negative or neutral (usually because the number of + and - cancel out). The fundamental charge carriers are protons (+) and electrons (-) and being so small it's hard to isolate them. But we can observe the EFFECTS of charge and impute its existence through some simple observations (1) opposite charges attract (2) like charges repel (3) the electric forces increase as the separation distance decreases and (4) electric forces increase with the amount of charge (or number of protons or electrons). I hope this helps.
Thank you so much for such a clear and concise explanation that was so helpful. Loved the animations!
Thanks for your support, Kunashni!
I learned way more than I had known before
Thank you ever so much
v pleased to hear that!
That's great to hear!
This is brilliant, thank you very much!
Great to hear, Thanks.
I'm beginning to "get it" after failing general Chem in H.S. but went on to medical school and never understood College general chem semesters, and organic chemistry was incomprehensible. Your video has been sensational and coherent, for which I thank you.
Thank you, Greg. Chemistry should be taught more straight-forwardly. The concepts are often much simpler than they are usually conveyed.
Best video
Sorry for the late reply. Thank you!!!
There is something that I can never come to grips with. Each element is differentiated by the number of protons, but all protons are the same. Why does the addition of protons, ie the same building blocks, make for different elements?
Hi Ray. Increasing the number of protons increases the overall charge on the atom's nucleus, so it pulls on its electrons more tightly. This consistently changes how it behaves and therefore what element it is. For a given Period (Row) all metals have relatively few protons thus allowing the electrons to be mobile, and thus conduct electricity specific to their own atomic number.
Also the number of electrons is the same in a neutral atom, and that affects chemical behaviour, too, especially the number of outer electrons. This is despite all electrons being the same.
Thank you for your response. Sometimes the simplest explanations are the best. Much appreciated. I stumbled across your channel and am so happy I did.
how calculate how much energy in units of electrinvolts [eV] each shell (1 to 7) and each subshell (s, p, d, f) has?
You can only do this for the hydrogen atom, using E = -E0/n2, where E0 = 13.6 eV (1 eV = 1.602×10-19 Joules). All subshells are degenerate, that is have the same energy level values.
Other atoms are complicated by having many protons, and electrons that shield the outer electrons, lowering their energy values The Schrodinger equation cannot be solved for them.
Thank you
... Why can't the energy of each element be calculated by using its atomic mass in E=mc^2 ?