Thursday, November 17, 2011

Chemistry Thursday: The atom!

The periodic table. You see it everywhere, but what the heck does it all mean? Take a look at it for a moment. It's arranged by atomic number, which is the number of protons in an atom's nucleus. Let's meet the atom!

When we look at the periodic table of elements, we're looking at the organization of atoms - carbon, oxygen, helium, uranium and so on. There are three parts of an atom. The proton, the neutron, and the electron.

The proton is found in the nucleus of the atom and is positively charged. Every element has a different number of protons. If it has 1 proton, it's hydrogen. Two protons and you've got helium. Six protons gives us carbon and 16 gives us sulphur. Change the number of protons, you change the element. We have the same number of protons as we do electrons, which leads to a neutrally charged atom.

The neutron is found in the nucleus of the atom and is neutrally charged. Change the number of neutrons, and you have an isotope! Normal, everyday carbon-12 has 6 protons and 6 neutrons - carbon-14 has 6 protons and 8 neutrons, giving us a radioactive isotope. (That's why they use it in carbon dating! It decays at a predictable rate, so we can measure the decay and figure out the age of something!) Carbon will always have 6 protons - that's what makes it carbon - but the number of neutrons can change slightly (in carbon it might be 8, it's never going to be 42!). When you hear about elements like uranium-238 or uranium-235, we're talking about isotopes, which are elements that have the same number of protons but different neutrons.

The electron is found swirling around the nucleus. It's really tiny compared to the proton and neutron, and it carries a negative charge. In a neutral state, an atom will have the same number of electrons as it does proton. There's a ton of interesting stuff out there on locating the electrons on an atom - uncertainty principles and all of that, but for now we're going to go with the basic idea that electrons are found outside the nucleus of an atom on things called orbitals.

Orbitals are represented in this picture by those blue lines, the electrons by the red dots!

When you read the periodic table, look at each element to decode its meaning! This is sodium from the first group or column on the periodic table. It is number 11, which means it has 11 protons and 11 electrons (because they are the same number). It weighs 23.0 grams per mole (which is 6.02 x 10(23) atoms in 23 grams of sodium) and it has that plus sign in the corner. This means that there is one electron swirling around on its outer orbital. (This will become relevant in time.)

If you like the periodic table as much as I do, download this periodic table and play periodic table Scrabble! I can't spell my name (Susan - Sulphur-uranium-sulphur-there's no A on its own!) but I can spell my best friend's husband's name - Cameron (Carbon-Americum-Erbium-Oxygen-Nitrogen) and genius (Germanium-Nitrogen-Iodine-Uranium-Sulphur). My last name is easy to create - it's just Ni2! This is a great way to learn where the elements are on the table and their abbreviations!

Join me later this week for a little more chemistry fun!


EsseBee said...

I've always wondered what I missed by not doing chemistry at high school, and now I know! I had actually thought I might try to learn a bit about it, but it's so confusing to my poor old brain, I'll continue to give it a miss. I do hope others appreciate your efforts more than I do. ^-^

Nancy Liedel said...

I am TRYING with chemistry. The problem is that anything that does not relate to cosmetic formulation is boring to me. Read adult ADHD, of course I've mentioned that before and my whako notes give it away every time.

I really want to learn more and spend a great deal of time at, It's free, I'm not spamming. I just think his mission is fantastic. Offer college level math, science and some history (high school and grade school stuff too) to everyone who has an internet connection, so they can learn. Just like what you do, Susan. Anyone who does that is amazing in my book. So, you and he are amazing.

Colleges, like MIT offer classes online too, but I don't always get those. My genius level sister went to Wesley College an did a semester at MIT and SHE didn't always get it. :) Not just me.

chowsr said...

Ah brings back memories. We used to have the Periodic Table Olympics where we'd have to memorize as many elements as we could in 30 min.
@ Nancy here's the TED talk for Khan Academy, which is where I first learned about it and I agree it's amazing what this man puts together for free.

I checked out the MIT stuff and I didn't think it was too bad, but I did my undergrad in chemistry.


Jane Barber said...
This comment has been removed by the author.
Susan Barclay-Nichols said...

Hi Jane! This is about the atom, not ions. When you see sodium on the periodic table, it's an atom. The plus in the corner of the entry on the periodic table means it has an extra electron. If we wrote this down, it would be Na.

When you see Na+, it is an ion and it means it has lost an electron, so it's positively charged.

Patterns Tried and True said...

Best blog I read in a while! Keep up the good work!
I was wondering, if you give me permission to borrow your 'mascot" for one blog I wrote?

Susan Barclay-Nichols said...

Hi Patterns Tried & True. One of the kids in my group designed and drew the mascot, so I don't feel comfortable sharing unless it's associated with my blog. But thanks for asking.