Today we will finally be learning about molecules! We will be learning about how atoms fit together to make molecules. We will be building molecules with tooth picks and gum drops. In this class you will get a visual understanding of what molecules are and how they work. You will experience the multidimensional of molecules.
If you are not here today read the below paper I wrote up for you. Also look up and do a little research on molecules. As a final part look up the angle of bonds. Atoms do not just bunch together randomly, they fit together in particular orders. New atoms join molecules as far away from other atoms as they can get.
Molecules:
Everything in the universe is made up of either atoms or empty space. But, atoms alone would be pretty boring, and not very useful. The cool thing is that atoms combine to make molecules! And molecules make up just about everything. The rocks and trees, cats and bird, and even you are made up of molecules.
Now, atoms do not just combine any old way. They follow rules as to how they combine. And some do not combine at all, unless they are forced!
That is really what chemistry is all about, learning how and why atoms combine the way that they do.
Atoms have valence electrons (don’t worry about what that means, just go with the flow for now) that combine with the electrons from other atoms, and that is how molecules are formed. Almost always, atoms are “happiest” if they have eight electrons in their outermost shell (eight valence electrons). Or, the atoms are also satisfied if they have no valence electrons. So, atoms like to combine with other atoms so that they wind up with those eight electrons.
For example. Oxygen has six valence electrons. Hydrogen has one valence electron. So, one oxygen tends to combine with two hydrogens. That way, the oxygen gets two more electrons (to make eight!), and the hydrogens each give up their only electron, so they have none. Confusing? Yes, it is. It took scientist a long time to figure that out.
To try another example. Sodium (Na) has one electron in its outermost shell (one valence electron), while Chlorine (CL) has seven. So, one sodium combines with one chlorine to make NaCl (ordinary table salt). The chlorine now has eight electrons, and sodium has none, and they are stable. Sodium is a shiny metal. If you put it in your hand, it would eat right through your skin to the bone! Chlorine is a very, very deadly gas. But, when you put them together, they make table salt. And guess what? We need salt to live (of course, too much is bad, but we have to have it to survive).
We can look at the periodic table to help us figure out how many valence electrons each element has. Those in the first column have one valence electron. Those in the seventh column have seven valence electrons (see that Chlorine is in that column).
Notice that the elements with four or less valence electrons want to give them up, while those with more than four want to get them. And then they are both happy.
A molecule is two or more atoms joined together. The molecule can share characteristics of the element or have totally new characteristics. Oxygen is a life sustaining element. We breath in O2, and essential component in our bodies, and we breathe out CO2, a deadly molecule. Our lungs transfer the oxygen into our red blood cells which transfer it throughout our body. Our lungs release the CO2 as waste. Breathing in CO2 at too high of a concentration will cause coma and eventually death. O2 and CO2 are very similar molecules that have drastically different results in the human body.
Other than the fact that your entire body is made of molecules why are they important? Well, their atomic composition tells us a lot about how molecules work in our body, and their uses. Ethanol and methanol are two very similar molecules. The chemical formula for ethanol is CH3CH2OH and the chemical formula for methanol is CH3OH. Ethanol is grain alcohol, a form of alcohol that is commonly enjoyed by the over 21 crowd. Methanol is wood alcohol, which is deadly for humans. (In the human body it breaks down into formic acid which can cause blindness, coma and eventually death.)
The difference between ethanol and methanol isn’t just the name, it is the extra CH2, group. The simple addition of one carbon and two hydrogens allows the human body to digest ethanol. It changes a poison into something edible.
As you can see from this, molecules can be very, very complicated. Proteins and carbohydrates can have thousands and thousands of atoms.
But, we will stick with the simpler molecules in this class. That is ok, because the simpler molecules are really just as interesting! When atoms combine, they can really change properties a great deal. Table salt is one example, with a toxic gas and a toxic metal combining to make something that is crucial for good popcorn!
Your bones, for example, are mostly made up of calcium. But it is not just pure calcium. In must be Calcium oxide, or calcium carbonate or one of many other combinations.
You may have noticed that the names of compounds follow a pattern. In general, especially for the molecules we will study, the names start with the electron donor (the atom or element that gives up its electrons, and is over on the left side of the periodic table) Then, the electron “grabber” is named. So, we have Sodium Chloride. Or Calcium Oxide. How about water? Why is that not called Hydrogen oxide??? Just because it is so common. But, you would certainly be correct in calling it that!
And, notice that the second part of the name is changed just a little bit. Chlorine becomes chloride, meaning it is an ion (another new word!). An ion is just an atom without the normal number of electrons, so that one is easy! The sodium in sodium chloride is also an ion.
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