Thursday, February 23, 2012

Chemistry Thursday: What is a molecule?

What does it mean if something is a molecule? "A molecule is an electrically neutral group of two or more atoms held together by covalent chemical bonds." (Wikipedia). In other words, a molecule is when you have two or more atoms bound together in some way. One atom does not make a molecule - hydrogen on its own is just an atom, but combine it with another hydrogen and an oxygen atom and you've got at water molecule!

A molecule may consist of atoms of the same element. Take a look at ozone - it consists of three oxygen atoms bonded together. It's O3 - an ozone molecule. So a molecule can contain two or more of the same element.

We can have small molecules - take something like sodium chloride - or large molecules - like DNA.

A quick aside...I've heard a lot of talk lately about how our skin absorbs oils or how oils penetrate our skin - this isn't really an issue. (Click here for a post on our skin!) Fatty acids are considered fairly decent sized molecules - as you can see from this oleic acid molecule - and they don't tend to penetrate our skin. (That's why jojoba oil is considered unique in that it likes to penetrate our skin through the hair follicles!)

I say "they don't tend..." because there could be some current research I haven't seen that shows that some of the smaller fatty acids can penetrate our skin or there could be some information on penetration enhancers that I haven't read. I can't be completely certain and completely up to the minute on my science here! 


Anonymous said...

I love Chemistry Thursday! Thank you Susan!

LabMuffin said...

This is great, you explained it really well! :)

p said...

I'm confused (and intrigued!) by your point about oils not actually penetrating our skin! If oils don't penetrate our skin, where do they go? Some oils feel like they hang around on the surface of the skin (coconut comes to mind), but what about those lightweight, seemingly "fast-absorbing" oils like sunflower oil? If none of the oils is actually penetrating the skin, what accounts for the difference in skin feel?

Oooh, and another question, now that I'm thinking about it - if our oils all sit on the surface of the skin, why are some oils occlusive and others not?

The post you linked to on the chemistry of our skin is fantastic! I've read it a couple times before, but I feel I have an aha! moment every time I revisit it. Your blog is such a wonderful resource!