Periodic Table Series - Part I

The next few entries (18 to be exact) will be focused on the different groups in the periodic table, which is divided into groups and periods. Periods are horizontal rows, while groups are vertical columns, which often include elements with similar or at least related chemical properties. These similarities result from a variety of factors.

First, elements in the same group share the same electron configurations in the outermost "shell" or electronic sphere (the place where electrons are likely to be found) of the atoms. This means that the elements have the same number and "type" of the electrons that are most likely to participate in chemical reactions.

The first group (starting on the left and moving right) of the periodic table, Group 1, includes Hydrogen and the alkali metals, which are:

• Lithium, Li

• Sodium, Na

• Potassium, K

• Rubidium, Rb

• Cesium, Cs

• Francium, Fr

Since the elements have clearly not been put into a very concise and well organized table (which has clearly not been named the "periodic table") and it is obviously not at all a simple matter to come by one of these nonexistent tables, you might want to memorize every single element in the periodic table... just for kicks.

So to aid you in this very important endeavor, I have come up with a few mnemonics. In their entirety, these learning devices will form a poem.

Herein Lies New Knowledge--Requisite Chemical Facts...

For some other useful mnemonics, check out the following link!

Cyanide's toxicity

Ever wonder why cyanide is so toxic? It looks pretty similar to a lot of other small anions... it has similar properties to a lot of other small anions... but it's also much more toxic than a lot of them. So what's so special about it?

All living, breathing humans (and other living, breathing prokaryotes) have an electron transport system/chain (ETS/C) in the mitochondiral membrane within their (our) cells. The main roll of this electron transport system is to--as the name implies--shuttle electrons around and in the process, make ATP. In other words, the electron transport system harnesses energy for the cells in our bodies. Without it, we can't really survive. It is part of the Kreb's cycle, which is a series of biochemical processes that break down food and convert it to energy. 

The last step carried out by the ETS involves the transfer of hydrogen from an enzyme called cytochrome oxidase to oxygen, thereby producing water. Cyanide interacts with cytochrome oxidase in such a way to prevent it from functioning normally in this last step of the ETS. As a result, aerobic metabolism slows way down but glycolysis, which produces pyruvate, continues chugging away. So pyruvate builds up in the cells and gets converted to lactic acid, thereby lowering the delicately balanced pH of the cell. Simultaneously, ATP production grinds to a halt. Without energy, our bodies stop working, i.e., we die. 

Chemiluminescence Demos at West Lake Middle School

Artificially Sweet

Did you ever wonder what was actually in those artificial sweetener packets you might add to your coffee? The popular names on the market are Equal, Sweet N' Low and Splenda, although there are now many commercially available varieties.

Essentially, most of them contain some modified form of sugar that is not metabolized in the same way as standard table sugar (sucrose), thereby adding no caloric value to your diet.

Below are the chemical structures of the compounds present in the three artificial sweeteners mentioned above. Equal contains a mixture of aspartame, maltodextrin and dextrose.
Sweet N' Low is composed of saccharin, potassium bitartrate and dextrose.

Finally, Splenda simply contains a chlorinated derivative of sucrose called sucralose, in which three "OH" groups (hydroxyl groups) have been replaced by chlorine.

Oil 101

(Image courtesy of Creative Commons)

Ever wonder where oil comes from? Or how it got there? Or how we get it out of there?

Oil is a "fossil fuel," which basically means it formed from fossils, i.e., the remains of plants/animals that died a very long time ago, most of which ended up at the ocean floor. "But how," you might wonder, "did the animal/plant carcasses get turned into oil just by being dead?"

Over time, layers of sediment formed on top of the animal carcasses and eventually a very hard surface (rock) developed on top of them. Trapped between layers of hard sediment, without any oxygen (an environment in which some microorganisms thrive), the plant and animal material was eaten, metabolized and "broken down" into basic, carbon-rich material, which mixed with the surrounding sediments to form shale. But more plants and animals died, and more rock settled on top of the already present rock, causing significant pressure and heat to build up within the layers of hardness. This caused the oil to boil out in the forms of what we call "crude oil" and "natural gas," which accumulated in other, more suitable locations, such as porous rocks, where it was trapped (by less porous rocks surrounding the more porous rocks).

Although forming the oil and getting it trapped within these rocks was clearly the hard part (oh just hundreds of millions of years or so of Earth doing its thing), getting the oil out is not so easy either. First, we need to know exactly where the oil is. Of course, there are many places all over the Earth where large amounts of oil are trapped. In order to find them, geologists typically send shock waves into the Earth through layers of rock and the reflected waves are analyzed to determine the presence or absence of oil. The reflected waves travel at different speeds, which are characteristic of the particular material through which they traveled.

Once the oil is located, oil drillers (e.g., Chevron) begin developing their plans--after having gained legal right to the land, of course--for drilling. Enter oil rig. Essentially, drill a big hole in the Earth, pump out the oil. A little bit of chemistry interwoven with this messy process, which I'll discuss in due time.

Jay Keasling in Newsweek

UC Berkeley Professor Jay Keasling was recently featured in Newsweek for his pioneering work on the development of a new route for the production of artemisinin, an effective antimalarial drug. Artemisinin had previously been extracted from wormwood plants, but the extraction process was time-intensive and not very efficient.

Keasling spliced wormwood genes into yeast DNA in such a way that the resulting cell would convert sugar into artemisinin. This new production method is much cheaper and more efficient than the previous method.

Even more importantly, the method will allow large scale production of artemisinin, which will be made available (and at a much lower cost) to the people who need it but could previously not afford it.

Cold Nuclear Fusion - Fact or Fiction?

Surely you have heard of the supposed "cold fusion," first reported in 1989 at a press conference (super sketch!) by Drs. Stanley Pons and Martin Fleischmann at the University of Utah. But did you ever wonder what it was? Or whether it actually works?

Nuclear fusion refers to the process by which multiple nuclei of similarly charged atoms unite to form a heavier atom and typically A LOT OF ENERGY--with the exception of atoms heavier than iron, which actually absorb energy on fusion. Due to the typically high energy output, nuclear fusion could potentially provide a useful source of energy for our growing--and increasingly demanding--global population. One significant problem is that the process typically occurs only at ridiculously high temperatures, such as those found in the Sun or in a hydrogen bomb. Not surprisingly, scientists have long been interested in designing cheap, safe and effective methods for controlled fusion to produce usable energy.

Pons and Fleischman described a system containing deuterated water (D2O), two palladium electrodes, and a current running through the electrodes. They claimed that the current caused the palladium electrodes to absorb deuterium atoms, which were then forced so closely together that they underwent nuclear fusion to produce neutrons and energy in the form of heat: "...fusion occurs, out of that comes one or two new elements of less mass, and the difference is the energy that comes out. And that then would boil water, essentially. And when you boil water, you can make steam. And when you make steam, you can drive a turbine. And if you can drive a turbine, you can create electricity..." (watch the press conference).

The two scientists concluded that cold fusion had occurred based on the results of a calorimetric experiment that showed a 4:1 ratio of heat put into the experiment versus heat released. They also analyzed the gas released by the reaction by mass spectrometry and observed the presence of tritium. Finally, they claimed to have captured the ejected neutrons from the reaction vessel with water, and the water was found to emit gamma rays of a characteristic wavelength.

Skeptical scientists immediately tried to reproduce a similar cold fusion and they found largely inconsistent results. Many suggested that the heat Pons and Fleischman observed was produced either by the current or by reactions in the water.

Even to this day, many scientists continue to pursue cold fusion as a viable energy alternative. Until someone disproves the process, it will remain elusive--maybe fact, maybe fiction. But the lesson remains: reputable, peer-reviewed scientific journals are a much more reliable medium than a press conference through which to share scientific results.