noble gas
Chemistry
Physics
Examples of noble gas in the following topics:
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The Noble Gases (Group 18)
- It has been possible to prepare only a few hundred noble gas compounds.
- The noble gas atoms, as do the atoms in most other groups on the periodic table, increase steadily in atomic radius from one period to the next due to an increasing number of electrons.
- Scientists have discovered that, since the heavier noble gas atoms are held together less strongly by electromagnetic forces than are the lighter noble gases, such as helium, the outer electrons of these heavier atoms can be removed more easily.
- The noble gases glow in distinctive colors when used inside gas-discharge lamps, such as neon lights.
- The excimers used for lasers may be noble gas dimers such as Ar2, Kr2, or Xe2, or, more commonly, the noble gas is combined with a halogen in excimers such as ArF, KrF, XeF, or XeCl.
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Formulas of Ionic Compounds
- Ionic formulas must satisfy the noble gas configurations for the constituent ions and the product compound must be electrically neutral.
- The charge on the cations and anions is determined by the number of electrons required to achieve stable noble gas electronic configurations.
- In order to achieve noble gas configurations, the magnesium atom needs to lose its two valence electrons, while the bromine atom, which has 7 valence electrons, requires one additional electron to fill its outer shell.
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Atomic Radius
- Radii generally decrease from left to right along each period (row) of the table, from the alkali metals to the noble gases; radii increase down each group (column).
- The radius increases sharply between the noble gas at the end of each period and the alkali metal at the beginning of the next period.
- In a noble gas, the outermost shell is completely filled.
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Indoor Pollution: Radon
- Radon gas, the result of radium's radioactive decay, can severely compromise indoor air quality.
- Radon is a dense, colorless, odorless noble gas that occurs naturally in the soil as the product of the radioactive decay of radium; it is a decay product of uranium and thorium, which occur naturally in the Earth's crust.
- It can be found in well water, natural gas sources, and building materials.
- Radon is a gas, but these decay products are solids that can attach to dust and enter the lungs.
- Radon levels can be tested through a number of available assays, and contamination can be addressed by sealing basements and cellars to prevent the exchange of gas with the surrounding soil or by increasing ventilation.
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Ionic Bonding and Electron Transfer
- This exchange results in a more stable, noble gas electronic configuration for both atoms involved.
- Both types result in the stable electronic states associated with the noble gases.
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Substances that Exist as Gases
- A pure gas may be made up of individual atoms (e.g. a noble gas or atomic gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide).
- The group VIII elements (helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe) and radon (Rn)) exist as monatomic gases at standard temperature and pressure (STP) and are called the noble gases.
- These gases, when grouped together with the monatomic noble gases are called "elemental gases. "
- Explore the structure of a gas at the molecular level.
- The process of a solid converting to a liquid is known as "melting"; liquid to a gas is "vaporization"; and gas back to a solid is "deposition."
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Electron Affinity
- Electron capture for almost all non-noble gas atoms involves the release of energy and therefore is an exothermic process.
- The electron affinities of the noble gases have not been conclusively measured, so they may or may not have slightly negative values.
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Internal Energy of an Ideal Gas
- A monatomic gas is one in which atoms are not bound to each other.
- Noble gases (He, Ne, etc.) are typical examples.
- where N is the number of atoms in the gas.
- Helium, like other noble gases, is a monatomic gas, which often can be described by the ideal gas law.
- It is the gas of choice to fill airships such as the Goodyear blimp.
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Writing Lewis Symbols for Atoms
- Proceeding to the column labeled 'III', we find that those elements (B, Al, Ga, In, ...) have three valence electrons in their outermost or valence level.
- These are all gaseous under normal conditions of temperature and pressure, and are called 'noble gases.'
- The significance in understanding the nature of the stability of noble gases is that it guides us in predicting how other elements will react in order to achieve the same electronic configuration as the noble gases by having a full valence level.
- Helium is one of the noble gases and contains a full valence shell.
- Unlike the other noble gases in Group 8, Helium only contains two valence electrons.
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Sulfur Compounds
- Sulfur forms stable compounds with most elements except the noble gases.
- Sulfur forms stable compounds with all elements except the noble gases.
- Hydrogen sulfide gas and the hydrosulfide anion are extremely toxic to mammals, because they inhibit the oxygen-carrying capacity of hemoglobin and certain cytochromes in a manner similar to cyanide and azide.
- Sulfur hexafluoride is a dense gas used as a nonreactive and nontoxic propellant.
- Unlike carbon monoxide, carbon monosulfide is only stable as a dilute gas, as in the interstellar medium.