Serial number name |
Element Name |
Symbol |
Element properties |
|
Element 2 |
He |
The relative atomic mass of helium is 4.003, the valence electron of helium is 1s2, the valence of helium is 0, this element is the most difficult to liquefy and is a rare gas. |
|
|
Element 10 |
Neon |
Ne |
The relative atomic mass of neon is 20.18, the valence electrons of neon are 2s2, 2p6, the valence of neon is 0, and the element is a rare gas. |
|
Element 1 |
Argon |
Ar |
The relative atomic mass of argon is 39.95, the valence electrons of argon are 3s2, 3p6, and the valence of argon is 0. This element is a rare gas and the most abundant rare gas in the air. |
|
Element 36 |
Kr |
Krypton |
The relative atomic mass of krypton is 83.8, the valence electrons of krypton are 4s2, 4p6, the valence of krypton is +2, and this element is a rare gas. |
|
Element 54 |
Xe |
Xenon |
The relative atomic mass of xenon is 131.3, the valence electrons of xenon are 5s2, 5p6, the valence of xenon is +4, +6, +8, and this element is a rare gas. |
|
Element 86 |
Rn |
Radon |
The relative atomic mass of radon is 222, the valence electrons of radon are 6s2, 6p6, the valence of radon is +2, and this element is a rare gas. |
Rare gases are also called inert gases or noble gases. They are group 0 elements on the periodic table. At normal temperature and pressure, they are colorless and odorless monatomic gases and are difficult to undergo chemical reactions. There are seven types of rare gases, namely helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn, radioactive), and ozone (Og, radioactive, artificial element).
(1). All rare gases are colorless, odorless, tasteless and slightly soluble in water, and their solubility increases with the increase of molecular weight
(2). All rare gas molecules are composed of single atoms, and their melting points and boiling points are very low. As the atomic weight growth, the melting and boiling points also increase. They can all be liquefied at low temperatures.
(3). The outermost electron structure of rare gas atoms is ns2np6 (helium is 1s2), which is the most stable structure. Therefore, under normal conditions, they do not react with other elements and have long been considered to be inert elements with extremely inactive chemical properties and cannot form compounds.
(1) Some production departments often use them as protective gases. For example, in the welding of precision parts or active metals such as magnesium and aluminum, as well as in the manufacturing of semiconductor transistors, argon is often used as a protective gas.
(2) Rare gases emit light when electricity is applied. The world’s first neon lamp was made of neon gas (the original meaning of neon in English is “neon lamp”). The red light emitted by neon lamps has strong transmission power in the air and can penetrate thick fog. Therefore, neon lamps are often used on beacons at airports, ports, and water and land transportation lines. Argon or helium is filled in the lamp tube, and it emits light blue or light red light when electricity is applied. Some lamp tubes are filled with a mixture of four or two gases, such as neon, argon, helium, and mercury vapor. Due to the different relative contents of various gases, a variety of colorful neon lamps are produced.
(3)A variety of mixed gas lasers can be made using rare gases. Helium-neon laser is one of them. The helium-neon mixed gas is sealed in a special quartz tube. Under the stimulation of an external high-frequency oscillator, inelastic collisions occur between the atoms of the mixed gas, energy transfer occurs between the excited atoms, and electron transitions are generated, which emit stimulated radiation waves corresponding to the transitions, near-infrared light.
(4). Medical treatment
Xenon lamps have high ultraviolet radiation and can be used in medical technology. Xenon gas dissolves in cell oil, causing cell anesthesia and swelling, thereby temporarily stopping the action of nerve endings and achieving anesthesia. As an anesthetic without side effects, people have tried a mixture of 80% xenon and 20% oxygen. Krypton and xenon isotopes are also used to measure cerebral blood flow, etc.
(5)Making artificial air
Helium and oxygen are mixed into artificial air, which divers can breathe. Because in the deep sea with greater pressure, if you breathe with ordinary air, more nitrogen will be dissolved in the blood. When the diver rises from the deep sea and gradually restores the normal pressure in the body, the nitrogen dissolved in the blood should be released to form bubbles, blocking the microvessels and causing “gas stasis”. The solubility of helium in the blood is much lower than that of nitrogen. If the above phenomenon does not occur, but the ordinary air is replaced by a mixed gas of helium and oxygen (artificial air).
(6) A variety of mixed gas lasers can be made, and the helium-neon laser is one of them.The helium-neon gas mixture is sealed in a special quartz tube. Under the encouragement of an external high-frequency oscillator, inelastic collisions occur between the atoms of the mixed gas, and energy transfer occurs between the stimulated atoms, resulting in electronic transitions and emitting stimulated radiation waves and near-infrared light corresponding to the transitions. Helium-neon lasers can be used as measurement tools and communication tools.
(7) Low temperature
The boiling point of liquid helium is -269℃, which is the most difficult to liquefy among all gases. Using liquid helium, ultra-low temperature close to absolute zero (-273.15℃) can be achieved. Liquid helium is an ordinary liquid with the properties of ordinary liquids. Liquid helium below 2.2 thousand is a superfluid with many abnormal properties. For example, it has super conductivity and very low viscosity. Its viscosity is 1% of the viscosity of hydrogen. Liquid helium can flow upward along the inner wall of the container and then slowly flow along the outer wall of the container. This phenomenon is of great significance to the research and verification of quantum theory.
