Gas

gasesgaseousgaseous stategas distributiongas-phasegaseous phasegfumesgas phaseAtomic gas
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).wikipedia
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Solid

solidsssolid state
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma).

State of matter

states of matterstatephysical state
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
Four states of matter are observable in everyday life: solid, liquid, gas, and plasma.

Liquid

liquidsliquid phaseliquid state
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
As such, it is one of the four fundamental states of matter (the others being solid, gas, and plasma), and is the only state with a definite volume but no fixed shape.

Atom

atomsatomic structureatomic
A pure gas may be made up of individual atoms (e.g. a noble 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).
Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms.

Carbon dioxide

CO 2 CO2carbon dioxide (CO 2 )
A pure gas may be made up of individual atoms (e.g. a noble 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).
Carbon dioxide (chemical formula ) is a colorless gas with a density about 60% higher than that of dry air.

Oxygen

OO 2 molecular oxygen
A pure gas may be made up of individual atoms (e.g. a noble 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 only chemical elements that are stable diatomic homonuclear molecules at STP are hydrogen (H 2 ), nitrogen (N 2 ), oxygen (O 2 ), and two halogens: fluorine (F 2 ) and chlorine (Cl 2 ).
At standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula.

Atmosphere of Earth

airEarth's atmosphereatmosphere
A gas mixture, such as air, contains a variety of pure gases.
The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity.

Plasma (physics)

plasmaplasma physicsplasmas
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
The plasma state can be contrasted with the other states: solid, liquid, and gas.

List of states of matter

For a comprehensive listing of these exotic states of matter see list of states of matter.
The classical states of matter are usually summarised as: solid, liquid, gas, and plasma.

Mixture

mixturesmixingadmixture
A gas mixture, such as air, contains a variety of pure gases.

Hydrogen

HH 2 hydrogen gas
The only chemical elements that are stable diatomic homonuclear molecules at STP are hydrogen (H 2 ), nitrogen (N 2 ), oxygen (O 2 ), and two halogens: fluorine (F 2 ) and chlorine (Cl 2 ).
At standard temperature and pressure, hydrogen is a colorless, odorless, tasteless, non-toxic, nonmetallic, highly combustible diatomic gas with the molecular formula H 2.

Nitrogen

NN 2 dinitrogen
The only chemical elements that are stable diatomic homonuclear molecules at STP are hydrogen (H 2 ), nitrogen (N 2 ), oxygen (O 2 ), and two halogens: fluorine (F 2 ) and chlorine (Cl 2 ).
At standard temperature and pressure, two atoms of the element bind to form dinitrogen, a colourless and odorless diatomic gas with the formula N 2.

Helium

Hehelium IIsuperfluid helium
When grouped together with the monatomic noble gases – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – these gases are called "elemental gases".
It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table.

Diatomic molecule

diatomicdiatomic moleculesdi-
The only chemical elements that are stable diatomic homonuclear molecules at STP are hydrogen (H 2 ), nitrogen (N 2 ), oxygen (O 2 ), and two halogens: fluorine (F 2 ) and chlorine (Cl 2 ).
The only chemical elements that form stable homonuclear diatomic molecules at standard temperature and pressure (STP) (or typical laboratory conditions of 1 bar and 25 °C) are the gases hydrogen (H 2 ), nitrogen (N 2 ), oxygen (O 2 ), fluorine (F 2 ), and chlorine (Cl 2 ).

Monatomic gas

monatomicMonoatomicmonoatomic gas
When grouped together with the monatomic noble gases – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – these gases are called "elemental gases".
It is usually applied to gases: a monatomic gas is one in which atoms are not bound to each other.

Neon

Neneon gas 21 Ne
A pure gas may be made up of individual atoms (e.g. a noble 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). When grouped together with the monatomic noble gases – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – these gases are called "elemental gases".
Thomson eventually concluded that some of the atoms in the neon gas were of higher mass than the rest.

Noble gas

noble gasesrare gas18
A pure gas may be made up of individual atoms (e.g. a noble 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). When grouped together with the monatomic noble gases – helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn) – these gases are called "elemental gases".
With this discovery, they realized an entire class of gases was missing from the periodic table.

Jan Baptist van Helmont

Jan Baptista van HelmontVan HelmontJan van Helmont
The word gas was first used by the early 17th-century Flemish chemist Jan Baptist van Helmont.
Van Helmont is remembered today largely for his ideas on spontaneous generation, his 5-year tree experiment, and his introduction of the word "gas" (from the Greek word chaos) into the vocabulary of science.

Chemical element

elementelementschemical elements
A pure gas may be made up of individual atoms (e.g. a noble 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 only chemical elements that are stable diatomic homonuclear molecules at STP are hydrogen (H 2 ), nitrogen (N 2 ), oxygen (O 2 ), and two halogens: fluorine (F 2 ) and chlorine (Cl 2 ).
Another commonly used basic distinction among the elements is their state of matter (phase), whether solid, liquid, or gas, at a selected standard temperature and pressure (STP).

Pressure measurement

manometerpressure gaugegauge pressure
His experiment used a J-tube manometer which looks like a test tube in the shape of the letter J. Boyle trapped an inert gas in the closed end of the test tube with a column of mercury, thereby making the number of particles and the temperature constant.
Pressure measurement is the analysis of an applied force by a fluid (liquid or gas) on a surface.

Pneumatic chemistry

gazomètrepneumatic chemists
For example, Robert Boyle studied pneumatic chemistry for a small portion of his career.
Important goals of this work were an understanding of the physical properties of gases and how they relate to chemical reactions and, ultimately, the composition of matter.

Viscosity

viscouskinematic viscositydynamic viscosity
Compared to the other states of matter, gases have low density and viscosity.
Gases, water, and many common liquids can be considered Newtonian in ordinary conditions and contexts.

Ideal gas

idealideal gasesideal-gas
Use of this distribution implies ideal gases near thermodynamic equilibrium for the system of particles being considered.
An ideal gas is a theoretical gas composed of many randomly moving point particles whose only interactions are perfectly elastic collisions.

Pressure

water pressurenegative pressurefluid pressure
Because most gases are difficult to observe directly, they are described through the use of four physical properties or macroscopic characteristics: pressure, volume, number of particles (chemists group them by moles) and temperature.
In a static gas, the gas as a whole does not appear to move.

Kinetic theory of gases

kinetic theorythermal motionkinetic
This particle or microscopic view of a gas is described by the kinetic-molecular theory.
The kinetic theory of gases describes a gas as a large number of submicroscopic particles (atoms or molecules), all of which are in constant, rapid, random motion.