Gases
Gases are a state of matter that exists in the space between particles. They have no fixed shape or volume, and can be compressed to fit into any container. Unlike solids and liquids, gases do not possess an inherent structure; instead, they move freely throughout their environment and take up whatever shape or volume is available to them.
In science, gases play an important role as a key component of many chemical reactions. For example, oxygen gas (O 2) is essential for respiration in living organisms, while carbon dioxide (CO2) plays an important part in photosynthesis processes by plants and other autotrophs. In addition, nitrogen gas (N 2), which makes up about 78% of the Earth's atmosphere, serves both as a source of energy for some bacteria species and helps regulate climate change due to its heat-trapping properties when released into the atmosphere from various sources, such as burning fossil fuels like coal or natural gas.
The behavior of gases can also be studied using mathematical models known as equations of state, such as the ideal gas law equation PV = n RT, where P represents pressure exerted on the walls of its container by a given amount of n moles of molecules with a temperature T at a constant volume V. These equations provide insight into how changes in pressure or temperature will affect certain physical properties related to gaseous substances, such as density or viscosity, allowing us to better understand how different types behave under varying conditions over time.