Week Two: Periodic Tables and Atomic Structures

1. Element(s) of the Week

I picked two elements because they are the only liquids at room temperature on the chart: Mercury and Bromine. This intrigued me. One is a metal, one is not. They are relatively far apart on the periodic table. And why are only two elements liquid? I discovered there are other metals some also consider liquid at room temperature, even though on the periodic table they are not noted as such: caesium, francium, gallium and rubidium. The reason for this is that only mercury and bromine are liquids "at standard conditions for temperature and pressure."

Bromine: the word comes from the Greek and means "stench of he goats." It's symbol is Br and the atomic number is 35. It is reddish brown. The vapors are corrosive and toxic. It is used as a fire retardant and is used in swimming pools in the way chlorine is--as a "water purifier." Bromine is the only liquid non-metallic element, In nature it is found in compounds in sea water, the Dead Sea, and in natural brines and salt lake evaporates . Bromine in the atmosphere leads to depletion of the "good" ozone layer and so the chemical is being phased out of many products that used to take advantage of its properties.

Mercury: Mercury's symbol is Hg and it's atomic number is 80. It is toxic and is shiny and silvery. The symbol Hg comes from the Latinized Greek word hydrargyrum meaning "watery" or "liquid silver." The element is named for the Roman God Mercury, who was known for his speed. It is used, as you probably know, in thermometers and other scientific instruments. Mercury is rare, but when it is found, it is found in high concentrations. Mercury is mostly gotten by reduction from the mineral cinnabar, which resembles quartz and is found, among other places, in California's hot springs. I went to Orr Hot Springs where mercury used to be mined. Some people are concerned about mercury being in the water there. Now I understand why. Cinnabar used to be used in Mayan burial sites because of its known toxicity (to scare away grave robbers). Many ancient cultures used mercury as make up and in concoctions intended to give eternal life; neither of these uses worked out very well.

Cinnabar:


Lots of things are named after Mercury -- from planets to newspapers to cars -- and very few after Bromine (or perhaps none -- there are no cars called Bromine). I guess it is more desirable to be quick and shiny than it is to be brown and stinky. If you want to insult someone in a chemistry nerd sort of way you could say, "Whatever, Bromine!"

Bromine:



2. Ozone discussions

I asked four people about ozone. My husband, a college educated person who loved chemistry in school, tentatively told me the following (he wasn't trusting his memory, though he was mostly correct):

It is three oxygen molecules; it is negatively charged; it is a filter/barrier to radiation/energy from space; it is biologically toxic; it is a pollutant that comes from cars?; there is good and bad ozone; it is lighter than a lot of atmospheric gases; CFCs react with ozone and turn it into something else which creates no ozone in the atmosphere; if we stopped polluting the atmosphere it would come back; we should ban the chemicals that pollute the atmosphere and put a cap on the human population and limit consumption of natural resources.

I also asked three teenaged boys what they knew about ozone. They said, "You mean the head shop in Alameda? I hate that place!" And they went on to discuss the head shop's owner in a most disgraceful way. I said, no, that's not what I mean. Oh, they said. Then one of them said something about the stratosphere and the atmosphere. Then another found a hula hoop in the yard and proceeded to show everyone how talented of a hula hooper he was.

3. Review of links

I might sound like a wimp or a dummy, but I don't think I have the mind of a chemist...yet? The simple information in the links I understand, but then begin to glaze over. Here's what I get:

Protons and neutrons exist within the nucleus of an atom. Electrons swarm about in a cloud outside of the nucleus. The atom has no electrical charge because the protons (which are positive) and electrons (which are negative) cancel each other out (atoms share the same number of protons and electrons). The atomic number will tell you the number of protons (and therefore also the number of electrons, since atoms contain the same amount of protons and electrons), and the atomic mass will tell you the number of neutrons (take the atomic mass and subtract the number of protons and it gives you the number of neutrons). Atoms have a structure. The electons build themselves up in "fields" (my term, I think) around the nucleus. Two electrons can be in the first field, eight in the second, and I think eight in the third. The fields -- oh, yes, they are called oribitals-- are organized as shapes. The first orbital is spherical. The second oribital is spherical. Then they become kind of complicated -- p's and d's and such. I'm a little lost there.

Elements are matter that cannot be paired down any further. One atom of an element can pair with another atom of a different element to make a molecule that is a compound. These compounds can be separated chemically, but not physically -- like water. Sometimes elements combine to make a mixture -- the elements do not actually attach themselves to each other. Mixtures can be separated physically. I'm guessing that in order to form compounds you probably have to add heat. Except in the case of that horrible thing I have heard is happening with regularity in Japan where kids are mixing bleach and ammonia (I think) and creating a deadly gas. Bleach and ammonia I am guessing are rather unstable and will happily intermingle to form a deadly gas compound without adding heat.

The information in the links on bonds kind of made me, well did make me, shut down. I want to wait to hear this information explained to me in class hopefully so that I can approach it with a little prior knowledge. I'm sure I had this in high school, but the information made a mixture in my brain that was easily separated out, instead of a compound that stuck.