QUESTION: Where does Helium come from?
ANSWER:  Helium has many uses and is safe if used wisely. The helium chemical symbol is He. It is the second lightest elemental gas, after hydrogen, and the smallest of all the molecules. It is the lowest boiling point of any element (-452.1°F, -268.9°C, 4.2 K, 7.6 R) and it is seven times lighter than air. Helium conducts sound three times faster than air, and has five times air's thermal conductivity; it is colorless, tasteless, odorless, inert, and non- flammable. It is non-toxic unless directly inhaled.
Most of the world's helium comes from the Texas panhandle, Oklahoma, Kansas and the Rocky Mountains' eastern flank, other sources include the mid-east and Russia. These natural gas deposits contain more than 3,000 ppm of helium. There is helium all around us in the air, but it is not a good source for helium collectors. There are only about 5 parts of helium for every 100,000 parts of air! People have discovered much richer sources of helium underground. Some radioactive elements, such as uranium, release alpha particles when they decay. An alpha particle is just a helium atom with no electrons. Deep in the Earth where these radioactive decays take place, the alpha particles capture electrons and become helium. As the radioactive deposits age, large quantities of helium become trapped in underground caverns. To collect the helium, people drill down into the caverns and capture the helium as it escapes.
Helium is a lot lighter than air. The difference is not as much as it is between water and air (a liter of water weighs about 1,000 grams, while a liter of air weighs about 1 gram), but it is significant. Helium weighs 0.1785 grams per liter. Nitrogen weighs 1.2506 grams per liter, and since nitrogen makes up about 80 percent of the air we breathe, 1.25 grams is a good approximation for the weight of a liter of air. Therefore, if you were to fill a 1-liter soda bottle full of helium, the bottle would weigh about 1 gram less than the same bottle filled with air. That doesn't sound like much -- the bottle itself weighs more than a gram, so it won't float. In large volumes, the 1-gram-per-liter difference between air and helium can really add up. Helium balloons work by the same law of buoyancy. The helium balloon displaces an amount of air (just like the empty bottle displaces an amount of water). As long as the helium plus the balloon is lighter than the air it displaces, the balloon will float in the air.
Most people are familiar with helium balloons. We put helium in these balloons, because it is lighter than air and is non-flammable. However, most of the helium used today is in liquid form. All gases become liquids when the temperature becomes low enough, or when excessive pressure is used. Scientists use liquid helium for experiments that have to be kept very, very cold. Helium becomes a liquid at 270oC below zero! Helium does leak out. Helium is a very small atom and latex is pretty porous at the scale of a helium atom (if you ever go looking to buy balloons, you will see that there are "helium-grade" balloons, which try to be thicker and less porous). You should always buy helium grade balloons to fill with helium. Even these balloons will only hold helium for 10 to 14 hours. Generally stores will only guarantee them for 8 hours. They can claim they will float for 12 to 14 hours, however after 8 hours they are starting to lose the helium and won't be floating as well. The weight balance that keeps a balloon afloat does not leave a lot of room for leakage, so once  a little helium leaks out, the balloon falls.
Helium is used in scuba tanks to dilute oxygen. It is chemically inert, that is to say, it does not participate in chemical reactions. Helium is also less soluble in water than many other gases, such as nitrogen. Low solubility means it does not enter the blood stream, even under pressures commonly experienced by deep sea divers. Instead, it displaces the oxygen, which is why it is so dangerous to directly inhale helium. Under water, a scuba diver is subjected to added pressure. In shallow water the pressure difference is not so great, and one can simply use compressed air to breathe. However, at a depth of 300 feet, a diver experiences nearly 10 times normal atmospheric pressure. Under these conditions, breathing compressed air can be harmful. The increased pressure requires an inert gas to be used to dilute oxygen. Oxygen is essential for breathing, above and beneath the surface. However, one can get too much of it. Under high pressures, greater amounts of oxygen enter into the bloodstream. If the concentration becomes too high, oxygen poisoning can result, with symptoms that include confusion, impaired vision and nausea. So, under high pressures, oxygen must be diluted with some other gas.
Nitrogen is very abundant and relatively inert, but it cannot be used to dilute oxygen in scuba tanks. At the elevated pressures experienced by divers, larger amounts of nitrogen will dissolve in the blood causing nitrogen narcosis. Dissolved nitrogen also can cause a painful condition, called "the bends" if a diver makes too rapid an ascent. As the pressure decreases, the dissolved gas can form bubbles that can stop circulation in capillaries and damage the nervous system.