Brimstone, barking dogs and glow sticks all share this lemon-yellow element

Next in our exploration of the periodic table is the element, sulfur, denoted by the symbol S and the atomic number 16. This lovely element, the tenth most common on Earth by mass, is a non-metal. Its most familiar allotrope is cyclooctasulfur, which is made of rings (thus the "cyclo" part of the name) comprised of eight sulfur atoms ("octasulfur"). It is a soft and bright lemon-yellow solid at room temperature. It can be found as yellow crystals.

Biologists and biochemists are familiar with sulfur because it is an essential element for life. All proteins contain sulfur, as do the B vitamins, biotin and thiamine.

"Native" sulfur, known in biblical times as "brimstone", is often found as elemental crystals near volcanoes and hotsprings, and is also produced through the metabolic activities of anaerobic bacteria. Jupiter's moon, Io, has a distinctive yellow hue that is attributed to various forms of molten, solid and gaseous sulfur belched out by its many volcanoes.

In this video, we watch our favourite chemists blow stuff up, as usual. Except in this case, this particular explosion has a special name: the barking dog experiment:

The barking dog experiment is the reaction between nitrous oxide gas (N2O) and carbon disulphide (CS2). In this reaction, the carbon disulphide reacts with the oxygen in the nitrous oxide to form the gases, carbon dioxide (CO2) and sulfur dioxide (SO2), and some pure sulfur, which is deposited as a yellow powder on the glass tube.

The barking dog reaction also releases a large amount of energy, most of which is released as heat, but far more than normal is converted into light -- a blindingly brilliant light. Converting chemical energy into light energy without heating anything up is known as chemiluminescence, and this process is something that you experience when you play with glow sticks.

For all you spelling purists out there (and I do know there are lots of you out there since my Americanised spellings of words are loudly criticised whenever they sneak past my mental spell-checker), I have to share a brief history of the proper English spelling of this element's name.

Originally spelled as "sulphur" in the UK and in the Commonwealth of Nations (or as "suphur" at the University of Nottingham's Chemistry Department), those pesky Americans (being the rebels they are) instead spelled it as "sulfur". Canada and the Philippines, which have strong relationships with both the United States and Great Britain, use both spellings. However, seeing discord, the International Union of Pure and Applied Chemistry (IUPAC) came along and standardised the spelling in 1992. Seeing as how the Americans got the spelling correct, they wisely adopted "sulfur" as the internationally correct English spelling.

This video (below) does not depict pure sulfur, but it captures a series of cute little experiments with sulfur hexafluoride, a colourless and transparent gas that is six times heavier than "air". In this video, a group of television news personalities are entertained by this gas, providing a rare glimpse into how easy it is to entertain the media (this video, as with all YouTube videos, appears and disappears almost at will these days, so if you don't see it now, refresh this page and it should pop up or visit again later):

Incidentally, the guest in that clip is Steve Spangler, an Emmy award-winning television personality, businessman and teacher. He enjoys being a guest on a variety of television programmes where he teaches viewers a number of useful life skills such as how to blow up their food, shock their friends, create mountains of foam, play on a bed of nails, vanish in a cloud of smoke and how to turn 2,500 boxes of cornstarch and a garden hose into a swimming pool of fun.

You've already met these elements:

Phosphorus: P, atomic number 15
Silicon: Si, atomic number 14
Aluminium: Al, atomic number 13
Magnesium: Mg, atomic number 12
Sodium: Na, atomic number 11
Neon: Ne, atomic number 10
Fluorine: F, atomic number 9
Oxygen: O, atomic number 8
Nitrogen: N, atomic number 7
Carbon: C, atomic number 6
Boron: B, atomic number 5
Beryllium: Be, atomic number 4
Lithium: Li, atomic number 3
Helium: He, atomic number 2
Hydrogen: H, atomic number 1



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