Gases may also flow, so they take up the entire shape of their container. They do not have a predetermined form. Because gas particles are significantly wider apart than liquid or solid particles, they may be pressed closer together. As a result, gases can be compressed or expanded.
Gases do not have a defined volume or form. Gases expand to fill the available area. They may also be crammed into a compact area. Compression does not create bonds or structures within the gas; it only increases the number of particles together.
Gases are usually described by the amount of pressure they can stand without collapsing. The higher the pressure, the less room there is between the particles and their forces become stronger. At some point these strong forces will overcome the ability of the gas to resist compression and it will collapse.
The specific volume of a gas is the volume that the gas would have if it were compressed to one particle per unit area. This is very difficult to measure experimentally, but it is usually estimated from knowledge of the other properties of the gas. For example, if we know the mass of the gas, its temperature, and its ideal gas law formula (which includes a constant called the Boltzmann constant), then we can calculate what fraction of its total volume is taken up by its particles and therefore estimate what its specific volume might be.
At standard temperature and pressure, the specific volumes of most gases are fairly close to 1/mpa where m is the mass in grams and p is the pressure in atmospheres.
Gases do not have a defined form or volume. The particles are constantly moving and spreading out. This is the reason why gas fills its container. When a gas is squeezed into a compact space, the particles become closer together. They may even overlap one another in some cases.
Gas molecules are always trying to regain their original shape. If they can't escape the container, they try to move into a less dense area - which causes them to spread out further.
This process of squeezing in and spreading out continues until all the molecules are back where they started from, and the container is full again.
As you can see, gas molecules change size when they're being compressed. They also tend to clump together. These effects mean that the volume of a gas can change while it's being compressed.
For example, if I were to compress nitrogen gas down to one half of its normal density, its volume would be reduced by about one-quarter. As another example, if I were to compress oxygen gas down to twice its normal density, its volume would be increased by about one-half.
It all depends on how much pressure is being applied to the gas. If it's only being subjected to low levels of pressure, such as those found at sea level, then it will remain relatively constant in size and number over time.
The particles in gases are substantially wider apart than in solids or liquids. Because the particles are always moving, a gas will fill any container that it is placed in. Because there is room between the particles, when the gas is compressed, they may be crushed into a smaller volume. However, there is no such thing as a solid particle moving around inside a gas container - all the movement is within the gas itself.
If some of this excess space were not taken up by other molecules, the gases would expand to fill their entire container. For example, if there were no other molecules for the particles of air to collide with, each particle of air would expand to fill its entire container - the sky! This is why airplanes need holes in their fuselages so the wind can move through them and not force the airplane down.
Gases are good conductors of heat because the electrons that make up atoms are mobile and can transfer energy through collisions with other particles. If two objects made of different materials are heated separately and then brought together, the electrons in the atoms of one of the objects will rush toward those of the other object to restore them to their original state. This electron flow is what allows metals to lose heat so easily and resist melting at high temperatures.
Because gases are good conductors of heat, they will also spread out across a container wall from a hot object faster than a thicker material like plastic.
Unlike solids and liquids, gas particles spread out equally to fill a container. When more gas particles enter a container, there is less area for them to spread out and they become compressed. This is why when you open a bottle of soda, it tends to be flat against the wall.
Gases are very useful in filling empty spaces. If there were no gases, then any empty space would be wasted energy. For example, there is not much use for an empty room unless it is intended to be a home for something else (i.e., furniture). The idea of gas compression helps us utilize resources wisely. Gas molecules are able to spread out while still covering enough ground that no area of the container is left empty.
At the molecular level, gases are made up of atoms that are made up of electrons orbiting a nucleus that is composed of protons and neutrons. The more electrons an atom has, the higher its atomic number will be. Helium has two electrons and is considered a noble gas because it does not react with other substances and is not affected by heat or light. Krypton has eight electrons and is also a noble gas. Argon has 18 electrons and is a monatomic gaseous element. Iodine has 35 electrons and is a polyatomic gaseous element. Xenon has 86 electrons and is a polyatomic gaseous element.