Tag: Science

n a multi-part series with the popular astrophysicist Neil deGrasse Tyson, Bill explores a variety of topics, including the nature of an expanding, accelerating universe (and how it might end), the difference between “dark energy” and “dark matter,” the concept of God in cosmology and why science matters. [..]

Starting in March, Tyson will host a new, updated version of the hit PBS television series Cosmos, which made the late Carl Sagan a household name. This time the new series, Cosmos: A Spacetime Odyssey, comes courtesy of the National Geographic Channel and Fox TV.

Magnesium, with a Z = 12, is an extremely common element in the crust of the earth, but it is never found in nature in the elemental state.  It is the second member, after beryllium, in the alkaline earth series of elements.  It is above calcium in that same group, and has significant biological roles.

As is the general trend for elements on the left hand of periodic table, magnesium is less reactive than calcium, just as beryllium is less reactive than magnesium.  This is due to the fact that elements in the first and second columns have their electrons more tightly bound the higher in the column they appear because of less shielding from other electron shells.

Before we begin tonight, please join me in paying my respects to my mum, who would have been 91 years old today.  The season beginning with Thanksgiving and lasting through New Year’s Day was her favorite of the year, and she showed lots of love to everyone during this time.  But she showed lots of love all year ’round.

The definition of an emulsion is two dissimilar liquids that are dispersed into a more of less long lasting mixture that has properties different than either of the two liquids.  I say dissimilar because in most cases one of the liquids is hydrophopic (literally, “water fearing”, often an oil or hydrocarbon) and the other one hydrophilic (literally, “water loving”, often water itself).

The old adage that oil and water do not mix is only partially true.  It is possible to make them mix, and it is often done intentionally.  Sometimes it happens upon accident, and we organic chemists know that when the synthetic product that we seek to isolate forms an emulsion with the solvent and/or other materials in the separatory funnel that is easy to become piqued by that.

Scotch whisky is quite different than most other distilled grain spirits.  First of all, it has its own spelling.  Except for Scotch, the spelling is “whiskey”.  In the case of Scotch, it is “whisky”.  I do not know if that is a Gaelic thing, but it is true.  Likewise, the plural of “whisky” is “whiskies”, whilst the plural of “whiskey” is “whiskeys”.  Actually, these distinctions are at best approximate, as some American brands of things that are not Scotch call themselves “whisky”.  But Scotch is almost always spelt “whisky”.

Actually, I am not sure if “Scotch” should even be the name for it.  Some of them call themselves “Scots’ Whisky”.  That might be a better way of saying it.

Now for the Geeky stuff.  Follow with me for several hundreds of years?

I was painting a wooden basket yesterday with boilt linseed oil and thus came the inspiration for tonight’s topic.  Drying oils are very important in the coatings industry, not as much as in the past but still important.

Back in the day before high quality water based paints had been developed, oil based paints were just about the only good choice except for some specialized applications.  Before we go into detail, we should define some key terms regarding to paint.

The vehicle is the part of the paint that forms a tough, adherent film.  In oil based paints the vehicle is generally linseed oil.  In latex paints the vehicle is some type of synthetic resin.

The second component (not always in paint, but usually) is the solvent, also called the diluent.  In oil paint the solvent is now usually petroleum distillates, but before oil was discovered the solvent was almost always turpentine.  In latex paints the solvent is water.

The pigment is composed of inorganic powders, usually white or colorless.  The pigment can add to the toughness of the film.  For commercial house paints the pigment does not provide color (except for white) and usually organic dyes are added to the pigment for colors, although some other materials are also used.  For art paints, many times the pigment is also the color in many cases.  Pigments are similar for oil and water based paints.

There are also additives in small quantities in most paints to modify drying rate, viscosity, surface tension, and other properties.  Water based paint often contains ethylene glycol as an antifreeze.

Today was a splendid day in the Bluegrass.  The temperature was in the low 70s, only a very light breeze, and not a cloud in the sky.  The Woman had gone to birthday party for a relative, but when she got home I took over the pumpkin pie that we had baked together last night and we each had a piece.  The crust, described here, was perfect.

I left a generous portion of the pie, and she gave me a big hunk of the pumpkin roll that we also made last night.  I knew that she was going to be busy later in the day, so I went nutting.  My target today was hickory nuts, getting ready for holiday baking.  There is a tree that is a reliable cropper just about half a mile from my house, in the yard of some very nice people who always tell me to get as many nuts as I care to pick up, and so I did.  Within an hour I had enough clean nuts for all of the holiday cooking, and then some.

Last time we started our discussion about sodium, and tonight we shall continue it.  We have pretty much covered the quantum mechanical part and the properties and uses of elemental sodium, so tonight we shall focus on some of the compounds of that element.

Sodium compounds are extremely common and widespread, but not universally distributed.  This is important for reasons to be seen later.

The most common sodium compound is common salt, or sodium chloride, NaCl.  Everyone has personal experience with salt, both as a nutrient and as a melting aid for icy surfaces.

Sodium, element number 11, is one of the most common elements in the crust of the earth.  Except for school laboratory demonstrations, few people have ever seen elemental (metallic) sodium because it is so reactive and actually has very limited consumer uses (that would be about zero consumer uses).

We have hinted at the concept of periodicity previously, like last week when we saw how similar the chemical behavior of helium and neon are.  The similarities betwixt hydrogen and lithium are much less marked than those betwixt lithium and sodium, mostly due to the extreme low mass of hydrogen, making quantum effects more pronounced.  Thus, sodium is the second alkali metal after lithium even though hydrogen is in the same column in the periodic table.

In other words, the two first row elements, hydrogen and helium, are aberrant because of their low masses AND because they have only the K electron shell in the ground state AND as a corollary, only the 1s orbital that is filled with only two electrons.  Starting with the second row, the L shell begins to be filled and it contains, in addition to the 1s orbital, a 2s and three 2p orbitals.  Row three elements, sodium being the first of which, also contain in addition to those orbitals, a 3s and three 3p orbitals, making them more like the second row than the second is to the first row.

An odd pair of solar system objects will be meeting up in the night sky tonight: the full moon and distant Uranus. You’ve got two opportunities to watch this sweet celestial action go down during two live Slooh Space Camera shows, the first at 4 p.m. Pacific/7 p.m. Eastern and the second at 7 p.m. Pacific/10 p.m. Eastern on Sept. 29. [..]

This weekend’s full moon will be known as the Harvest Moon, since it occurs nearest to the autumn equinox. Uranus will be in opposition to Earth, meaning it will be as close and bright as it can be in the night sky, and will be nearly perfectly lined up with the moon. Amateur astronomers can get a good glimpse at Uranus by aiming just below the moon and searching for the only green star in their field of view.

The Slooh show will be hosted by Patrick Paolucci, who will be joined by Bob Berman, columnist for Astronomy magazine.

h/t Adam Mann at Wired Science

Last time we talked about fluorine, the very most reactive chemical element.  Now we add a single proton to the fluorine nucleus and come to Element 10, the LEAST reactive chemical element.  What a difference a charge can make!

Actually, neon is quite common in the cosmos but quite rare on earth.  It is fifth, after the elements that we have already discussed, because it is mostly a light even/even nucleus.  But that is not what makes it outstanding.

There are three stable isotopes of neon, ²⁰Ne, at almost 91% natural abundance on earth, ²¹Ne, at about a quarter on one per cent, and ²²Ne, the remainder.  This gets important later.

Element 9, fluorine, is the first of the halogens, from the Greek halos, “salt”, and gonos, “to bring forth”.  All of the members of this family tend to form salts with metals, but fluorine is unique amongst the halogens in that it forms compounds with EVERY element ever tried except for helium and neon.

Fluorine is by far the most reactive element, having everything just right for extreme chemical behavior.  It is a small atom that forms a small ion.  Its electrons are tightly bound in its ionic form, but oddly molecular fluorine has a remarkably weak bond for a halogen, only iodine having a weaker one.

The element has been known in the form of naturally occurring salts since the Middle Ages, when these minerals were used as fluxes in metal smelting.  The purpose of a flux is to make the ore and reducing agent mixture easier to melt, thus speeding the reaction since liquid state reactions occur much faster than solid state ones.  A secondary use of a flux is to protect the newly won metal from atmospheric oxygen by forming a protective layer that floats on the metal.

Last time we discussed oxygen as an element, including why we do not burst into flame in our 21% oxygen atmosphere.  Quantum mechanics can really be interesting.

This time we shall discuss some of the compounds of oxygen with other elements, and I emphasize SOME because oxygen forms hundreds of thousands if not millions of compounds.

Some of these compounds are essential industrial materials, some are essential for biological processes, and some of them can cause real problems when released into the atmosphere.  A few of them are quite toxic.  Let us look into them!