At stp which list of elements contains

This particular resource used the following sources:. Skip to main content. Search for:. Substances that Exist as Gases. Key Points A gas is one of the three classical states of matter the others being liquid and solid. Under standard temperature and pressure STP, or 1 atm and K , a substance which exists as a gas is called a pure gas.

If the boiling point of a substance is below K, then the substance to be in gas form at STP. The fusion of hydrogen atoms in stars to produce helium produces huge amounts of energy; the energy in sunlight is captured by plants in photosynthesis, and drives most of the chemistry of living organisms. The most common isotope of helium, helium-4, consists of two protons and two neutrons in the nucleus, surrounded by two electrons.

Helium is found along with some radioactive minerals that decay by alpha particle emission, however the concentration of helium in these minerals is very low. The main source of helium is from natural gas, where it is separated out from the other components by fractional distillation.

Helium liquefies at 4. Some materials become superconductors when immersed in liquid helium; in these materials, there is no resistance to the flow of electricity. Superconducting magnets are used for an important medical imaging technology called Magnetic Resonance Imaging MRI , which allows images of tissues and organs to be obtained.

A related technology is used by chemists to obtain information that can be used to deduce the structures of molecules; this technique is called Nuclear Magnetic Resonance NMR ; the two technologies are basically the same, but the term "nuclear" is avoided in the medical application because of its unpleasant associations even though there is no nuclear radiation involved.

Helium is also used in blimps, where the combination of being lighter than air and nonflammable makes it much safer than hydrogen as demonstrated in the explosion of the Hindenburg. It is also used in deep-sea diving, since helium is less soluble in the bloodstream than nitrogen, and reduces the risk of the diver suffering nitrogen narcosis, high pressure nervous syndrome HPNS , or the bends.

Breathing helium gas causes the voice to become higher pitched because helium is less dense than air, changing the frequency of the sound waves generated in the larynx.

Neon is a colorless, odorless, unreactive gas which liquefies at Neon was discovered in by Sir William Ramsay see entry on Argon below and his assistant Morris Travers while working with a sample of krypton. The name comes from the Greek word for "new," neos. It is found in the Earth's crust at a concentration of 70 ppt, making it the 80th most abundant element; it is found in the atmosphere at a concentration of 18 ppm by volume.

Neon which is used commercially is extracted from liquid air by fractional distillation. Neon is used primarily in neon lights ; stimulating neon with electricity causes it to emit an intense red light. Other noble gases are used in "neon lights" as well, to produce different colors. Neon is also used in some underwater breathing mixtures; liquid neon is used in low-temperature cooling. Argon is a colorless, odorless, unreactive gas which liquefies at It is found in the Earth's crust at a concentration of 1.

Argon which is used commercially is extracted from liquid air by fractional distillation. Argon had been observed before by Henry Cavendish in , but it had not been identified as an element. Bromine symbol Br and atomic number 35 is a reddish-brown liquid, with a melting point of Mercury symbol Hg and atomic number 80 is a toxic shiny silvery metal, with a melting point of When the temperature is slightly warmer, there are a few other elements found as liquids at normal pressure:.

These four elements all melt at temperatures slightly higher than room temperature. Francium symbol Fr and atomic number 87 , a radioactive and reactive metal, melts around K. Francium is the most electropositive of all the elements. Although it's melting point is known, there is so little of this element in existence that it's unlikely you'll ever see a picture of this element in the liquid form. Cesium symbol Cs and atomic number 55 , a soft metal that violently reacts with water, melts at The low melting point and softness of francium and cesium are a consequence of the size of their atoms.

In fact, cesium atoms are larger than those of any other element. Gallium symbol Ga and atomic number 31 , a grayish metal, melts at Gallium can be melted by body temperature, as in a gloved hand. This element displays low toxicity, so it's available online and may be used safely for science experiments.

In addition to melting it in your hand, it can be substituted for mercury in the "beating heart" experiment and can be used to make spoons that vanish when used to stir hot liquids. Rubidium symbol Rb and atomic number 37 is a soft, silvery-white reactive metal, with a melting point of Rubidium spontaneously ignites to form rubidium oxide. Like cesium, rubidium reacts violently with water. The elements copernicium and flerovium are man-made radioactive elements. Not enough atoms of either element have been made for scientists to know their melting points for certain, but predictions show both of these elements form liquids below room temperature.

Both elements boil well above room temperature. That state of matter of an element may be predicted based on its phase diagram. While temperature is an easily controlled factor, manipulating pressure is another way to cause a phase change.