Acetylene (Ethyne) – a colorless gas used as fuel in blow-lamps when cutting and welding metals, and also in the synthesis of acetaldehyde. It is extremely reactive – see http://www.youtube.com/watch?v=X1LwYJ8pDhc

Carbon dioxide – is used by plants in photosynthesis, and it is produced during respiration by plants and animals. It is made when we burn fossil fuels and it is also released from volcanoes.

Xenon fluoride –This molecule is square planar, because Xenon has two lone pairs of electrons above and below the plane of the molecule. It reacts readily with water, even pulling water from air, so it must be kept in anhydrous (dry) conditions.

Formaldehyde – is quite reactive and a common building block in making  more complex compounds. Aqueous solutions of formaldehyde are called formalin which also contains a small amount of methanol to stabilize the formaldehyde. Formalin is used  to preserve animal specimens for study.

Ethylene (Ethene) – is produced from crude oil or natural gas by a process called steam cracking. It is an important building block in making a range of compounds, since it can undergo many types of reactions.

Sulfur dioxide – has a variety of uses including chemical synthesis, bleaching, winemaking and preservation of food. It has a strong smell and is produced in volcanoes. The real bond angel is 119 degrees.

Water – Well, you all know what that is! The most abundant molecule on the Earth’s surface, essential to life, making up between 55% and 78% of the human body. The real bond angle is not 90 degrees but 104.45 degrees.

Hydrogen peroxide – is one of the strongest oxidizers around and one of its uses is paper bleaching.

Nitric oxide dimer – Nitrogen oxide forms a relatively stable dimer (two molecules joined together) on silver surfaces. It is shown in a trans configuration (the oxygens point away from each other), to fit in the game.

Chlorine trifluoride – is a very unpleasant chemical, toxic and intensely reactive. During the 2^nd World War, it was used to make incendiary bombs. The molecule is T-shaped because the chlorine atom has five electron-pairs in its outer shell and while three of these are in Cl-F bonds, two are non-bonding ("lone") pairs. These keep as far apart as possible, minimizing repulsion (pushing apart) between each of the negatively charged clouds, by having a trigonal bipyramidal arrangement.

Thiocyanic acid – is an unstable compound.

Isocyanic acid – is volatile and poisonous.

Hypochlorite – is unstable and a good oxidizing agent that can react with many other molecules.

Carbonate ion – is present in many important minerals such as calcium carbonate, which is the main molecule in  limestone. In carbonated water, carbon dioxide has been dissolved, which results in the formation of carbonic acid, which in turn is dissolved into bicarbonate and hydrogen ions, and further into carbonate ions and hydrogen ions, making the liquid acidic.

Oxalate –This ion is found in a bush called greasewood (Sarcobatus) and animals that eat it can die from poisoning. There have been reports of mass deaths in flocks of sheep.

Nitrosonium – a cation (positive ion) created by removing one electron from nitric oxide.

Nitronium – an unstable cation (positive ion) created by removing one electron from nitrogen dioxide. The resonance structure shown here is a strong electrophile (attracts electrons) because it follows the octet rule.

Nitric acid – is a molecule with both a positive and a negative charge. It is a strong acid that can cause severe skin burns. In aqueous solution you’ll find it dissociated into a hydronium ion and a nitrate ion.