The Mostly Inorganic Carbon Quiz

Answer: A Latin word meaning "coal"

The word "carbon" comes from the Latin "carbo", which means "coal". In some languages, derived from Latin, "carbon" can mean both "coal" and the element. Because carbon is commonly found in nature in its elemental form, it was one of less than a dozen elements known since ancient times.

Answer: Atomic number

The atomic number of an element is the number of protons in the nuclei of its atoms. The mnemonic "Harry He Likes Beautiful Big Cars, Not Over Fast..." can be used to help remember the order of the elements in increasing atomic number. "Cars" is the sixth word in the mnemonic, reminding us that carbon is element atomic number 6.

Answer: Carbon-14

The number in the isotope name is the mass number, which is the number of protons plus neutrons in the nuclei of its atoms. The number of protons stays the same, but the number of neutrons varies, which makes isotopes. Carbon-11 is radioactive, but does not exist in nature, having a half-life of just 20 minutes! Both carbon-12 and carbon-13 are stable. Most natural carbon is carbon-12, only 1.1% is carbon-13, and carbon-14 is about one part per trillion! It is significant because the amount of carbon-14 can help date archaeological samples.

Answer: Silicon, germanium, tin, lead

The carbon group is also known variously as Group IV, Groups IVA and IVB, or in modern IUPAC parlance, as Group 14. All the members of this group - carbon, silicon, germanium, tin, and lead - have exactly 4 electrons in their outer shells, but the number of inner shells makes a big difference in their properties.

Answer: Quartz

Diamond and graphite are both crystalline forms of carbon - the different crystal structures give them their different properties. Amorphous carbon has no continuous crystalline structure - soot is mostly amorphous carbon. There are also a number of recently discovered or created carbon allotropes like buckyballs and carbon nanotubes.

Answer: Conducting electricity

Graphite is such a good conductor of electricity that it is used to make the electrodes for electric arc furnaces. Like diamond, it has a high melting point. It isn't malleable - as demonstrated by the brittleness of pencil "leads". Graphite certainly isn't transparent, but is a grey solid with a metallic lustre. The remarkable differences between diamond and graphite are due to their very different structures.

Answer: Carbon can form four covalent bonds

Carbon is said to be tetravalent because it has four electrons in its outer shell, and it can easily form four covalent bonds. However, they don't have to be to four other atoms, because carbon readily forms double and triple bonds with itself.

Answer: Silicon carbide

Carborundum is nearly as hard as diamond - it is listed at 9 on the Mohs scale where diamond is a 10. It is mostly produced synthetically in an electric batch furnace, although very small amounts are found in nature as the mineral moissanite, mostly in meteorites.

Answer: Calcium carbide

When calcium carbide reacts with water, it fizzes, producing acetylene gas, which is then burnt, producing a bright light. A curved mirror then produces a broad beam, favoured by cavers. However, these lamps could not be safely used by coal miners because of the flammable gases often present in coal mines, which led to the invention of the Davy safety lamp.

Answer: CN-

Cyanide is a notorious and deadly poison, binding with iron in important cellular enzymes, and making cells unable to use oxygen to get energy. Hydrogen cyanide gas was used in the Nazi death chambers in World War II, and cyanide was used in a number of famous murders, suicides and lately terrorist actions. You should be warned that cyanide is found in exhaust fumes, cigarette smoke and in the fumes produced when certain plastics are burned.

Answer: Prussian blue

It is thought that Prussian blue was first created by the Berlin paint maker Diesbach in Berlin, around the year 1706. It rapidly became popular with artists as far away as Japan, since earlier blue pigments were either prone to fade or very expensive.

It is still used in many paints and is the traditional "blue" in blueprints. Because the cyanide is already tightly attached to the iron, ferrocyanide is not especially poisonous, and is actually used as an antidote to heavy metal poisoning from thallium or caesium-137.

Answer: Herbicide

Carbon tetrachloride was once used as a pesticide to kill insects in stored grain, but never as a herbicide. It is a good solvent for organic chemicals. This ability to dissolve stains led to extensive use in the dry-cleaning industry. It is not flammable, so was once used in fire extinguishers. It was also used to make the freon refrigerants which are now banned. Carbon tetrachloride is bad for you, and bad for the environment, so its manufacture has much declined.

Answer: Carbon disulphide

Most samples of carbon disulphide are contaminated with impurities, like carbonyl sulphide, and hydrogen sulphide, which explains that rotten egg odour. Much of the carbon disulphide manufactured today is used in the production of cellulose fabrics like viscose and rayon.

Answer: Carbon dioxide

Those are all real oxides of carbon. Carbon monoxide is a very toxic gas commonly formed by incomplete combustion - people die from carbon monoxide poisoning caused by things like leaving cars running in enclosed garages quite regularly. Carbon suboxide is O=C=C=C=O and was discovered by Brodie as long ago as 1873.

It is quite stable and described as an "evil-smelling gas". Carbon trioxide (CO3) is unstable, and formed in odd places like inside a negative corona discharge. There are in fact quite a long list of oxides of carbon, most of them not especially stable - if you're curious check the Wikipedia entry for oxides of carbon.

Answer: Hydrogen

Organic chemistry is usually defined as the study of the compounds of carbon with hydrogen and other elements. There has to be carbon and hydrogen, other elements are optional. Occasionally, chlorine or fluorine substitute for the hydrogen. It was once thought that these chemicals could only be made by living things, hence the term "organic".

The big upset occurred in 1828, when Friedrich Wöhler made the organic chemical urea, found in urine, from inorganic chemicals. The modern usage of "organic" as "naturally produced" is quite different to the meaning of "organic" in the scientific context, and can certainly confuse students!