The Periodic Table

[DonRocks]

Having just power-watched "Breaking Bad," I asked myself, 'Is there anything in this world that you are truly ignorant about, that is more "basic and fundamental" to life, than The Periodic Table?'

I couldn't think of anything. So I'm going to teach it to myself, and post about it here as I learn it - I figure that if I don't understand it, then others may not either. It's pretty remarkable, actually - this giant chart had been posted up on the wall of probably dozens of classes that I've taken during my lifetime, and nobody ever really explained it to me (or, maybe they did, and I just forgot).

So, if you follow this thread, you'll eventually understand The Periodic Table, because I'm going to explain everything about it, as I learn it. I'll be using the approach that, "Nothing is too simple to put into writing," although I'm going to assume things such as, "people know the difference between atoms and molecules," that "people understand that atoms are comprised of protons, neutrons, and electrons" (without necessarily understanding exactly what they are, or where they reside), etc.

I have no doubt that an intelligent eighth-grader could explain this whole thing to anyone in ten minutes, but I'm going to do it step-by-step, little-by-little, so I don't overwhelm people with information. Writing things down will also help me to store them in my long-term memory, so presenting this little tutorial will benefit me as well.

If Ken Burns can do it with The Civil War, then hopefully I can do it with The Periodic Table. This might take a year (as it's a "spare-time project"), but it will hopefully get done, and if you don't understand everything about it when I'm finished, then that means I'm a failure as a communicator.

Kind of sad that if people remembered every single thing they were taught through middle school, they'd be more educated than 99.99% of the world.

A related thread: "Isotopes for Dummies" (most of the information in the first two posts there is of primal importance to eventually understanding The Periodic Table, but I don't want to get too far ahead of myself). Also in that thread, porcupine's link to "orbits and orbitals" is well-worth reading and committing to memory, but again, I don't want to get too far ahead of myself.

Feel free to correct me if you see mistakes (or just chime in to say hello!), but remember that I'm starting from an embarrassingly low-level of knowledge, and will eventually get around to correcting my own mistakes as I progress.

On other notes, my three most-recent meals have been: Pepita Cantina, Yona, and Kapnos Taverna.

[Al Dente]

A few days ago I was listening to a Radiolab podcast called "Elements". The stories about Lithium, Carbon, and Xenon were fascinating.

"Elements" on radiolab.org

We are stardust, we are golden, we are billion year-old carbon,
And we got to get ourselves back to the garden.

--Joni Mitchell

[Al Dente]

Some helpful music:

 

 

[Al Dente]

An Interactive Periodic Table on elements.wlonk.com.

 

[DonRocks]

Why Is It Called "The Periodic Table?"

Well, I *told* you I was going to start with the basics!

"Periodic" means "of or pertaining to a period."

A "Period" in the periodic table is a "row" - think of it as a sentence, read left-to-right (which has a period at the end of it).

There are 7 periods in the periodic table (including 2 "extra rows" at the bottom - if you look at the single- and double-asterisks in the chart above, you'll see that these extra rows can be "plugged into" periods #6 and #7, just like pieces in a jigsaw puzzle, but are presented as such for readability.

A vital concept:

Every element in the same period has the same number of electron shells, which raises the question, "What's an electron shell?" However, an even-more basic question is, "What are the columns?" For example, why are all the elements in the leftmost column, except for Hydrogen, displayed in red?

Your takeaway from this: The periodic table consists of 7 periods.

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I'll get to this later, but there's also an "Extended Periodic Table," first suggested in 1969, and containing an 8th period. This "8th period" contains elements with a higher number than #118, and these elements are currently only theoretical, i.e., they've never been discovered or synthesized, but there's no known mathematical or physical reason why they can't be.

(Please keep in mind, I'm learning as I go, so I have no "future knowledge" of what I'll be writing next.)

[DonRocks]

"Now We Know What a 'Period' Is, but What Are the Colums?"

Just as a row is called a "period," a column is called a "group" (you can see this very clearly at the upper-left corner of the picture). But why is it called a group?

Because everything in the same columns can be "grouped" together, as they have something important in common. 

Remember from above: "Every element in the same period has the same number of electron shells," so that's what the elements in each row have in common.

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Let's take a moment to define "electron shell."

An electron shell is one, single group of electrons in the same "orbit" around the nucleus. This is easily visualized by the analogy of our own solar system: Picture the sun as the nucleus, and each planet (and its orbit) as an electron shell. Assuming you no longer consider Pluto to be a planet, there are exactly 8 "electron shells" in our solar system, revolving around its "nucleus," the Sun. 

The "solar system" analogy breaks down when you consider that there's only one planet in each orbit, whereas electron shells can have numerous electrons (as you can see from the drawing below).

Picture also the shell of an oyster - something surrounding what's in the middle. A given element's atom can have 1-7 electron shells surrounding its nucleus (and this is why there are 7 periods).

Here is a drawing of element #108, which has 7 electron shells (and a total of 108 electrons). Notice that in its outermost electron shell, it has 2 electrons <--- this is an important sentence.

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Within each group (or column) - every element has the same "core charge" in its outermost electron shell, but what is a "core charge?" It isn't simply the "number of electrons."

Since "core charge" isn't the same as "the number of electrons," the term will be unraveled in the next post: For now, there are two simple things to remember - you should recognize every term used in these two items (with the exception of "core charge"):

1) There are 7 periods, with each period consisting of elements having the same number of electron shells.

2) There are 18 groups, with each group consisting of elements having the same core charge in their outermost electron shells.

To ponder for next time: Element #108 (Hassium) is in period #7 and group #8. Why is this element in group #8 when it has only 2 electrons in its outermost electron shell?

Also - and this is a term that you must memorize - "atomic number" means, simply, the number of the element in the periodic table. So element #108 has an Atomic Number of 108 - it's as simple as that, but it's a term you must know.