Search results
Results from the WOW.Com Content Network
A chemical substance is a unique form of matter with constant chemical composition and characteristic properties. [12] [13] Chemical substances may take the form of a single element or chemical compounds. If two or more chemical substances can be combined without reacting, they may form a chemical mixture. [14]
The structure of Earth can be defined in two ways: by mechanical properties such as rheology, or chemically. Mechanically, it can be divided into lithosphere, asthenosphere, mesospheric mantle, outer core, and the inner core. Chemically, Earth can be divided into the crust, upper mantle, lower mantle, outer core, and inner core. [6]
Superconductor: Material produced from a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain substances when cooled below a characteristic critical temperature. Superconductivity is the ground state of many elemental metals. Superconductors come in multiple varieties:
Earth's surface is the boundary between the atmosphere, and the solid Earth and oceans. Defined in this way, it has an area of about 510 million km 2 (197 million sq mi). [12] Earth can be divided into two hemispheres: by latitude into the polar Northern and Southern hemispheres; or by longitude into the continental Eastern and Western hemispheres.
However, the majority of familiar solid substances on Earth are made partly or completely of crystals or ionic compounds, which are not made of molecules. These include all of the minerals that make up the substance of the Earth, sand, clay, pebbles, rocks, boulders, bedrock , the molten interior , and the core of the Earth .
The term phase is sometimes used as a synonym for state of matter, but it is possible for a single compound to form different phases that are in the same state of matter. For example, ice is the solid state of water, but there are multiple phases of ice with different crystal structures, which are formed at different pressures and temperatures.
Carbon-based photosynthesis life caused a rise in oxygen on Earth. This increase of oxygen helped plate tectonics form the first continents. [10] It is frequently assumed in astrobiology that if life exists elsewhere in the Universe, it will also be carbon-based. [11] [12] Critics, like Carl Sagan in 1973, refer to this assumption as carbon ...
Water is an inorganic compound with the chemical formula H 2 O.It is a transparent, tasteless, odorless, [c] and nearly colorless chemical substance.It is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent [20]).