Oxygen
Chemical element with the symbol O and atomic number 8.
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Chemical compound
Chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds.
Chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds.
For example, a water molecule has formula H2O indicating two hydrogen atoms bonded to one oxygen atom.
Gas
One of the four fundamental states of matter .
One of the four fundamental states of matter .
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).
Carbohydrate
A carbohydrate is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula Cm(H2O)n (where m may or may not be different from n).
Abundance of the chemical elements
Measure of the occurrence of the chemical elements relative to all other elements in a given environment.
Measure of the occurrence of the chemical elements relative to all other elements in a given environment.
For example, the abundance of oxygen in pure water can be measured in two ways: the mass fraction is about 89%, because that is the fraction of water's mass which is oxygen.
Diatomic molecule
Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements.
Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements.
If a diatomic molecule consists of two atoms of the same element, such as hydrogen (H2) or oxygen (O2), then it is said to be homonuclear.
Atmosphere of Earth
Layer of gases retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere.
Layer of gases retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere.
By mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases.
Ozone
Inorganic molecule with the chemical formula .
Inorganic molecule with the chemical formula .
It is an allotrope of oxygen that is much less stable than the diatomic allotrope, breaking down in the lower atmosphere to (dioxygen).
Water
Inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent ).
Inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a solvent ).
Its chemical formula, H2O, indicates that each of its molecules contains one oxygen and two hydrogen atoms, connected by covalent bonds.
Fat
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term may also be used more broadly as a synonym of lipid—any substance of biological relevance, composed of carbon, hydrogen, or oxygen, that is insoluble in water but soluble in non-polar solvents.
Joseph Priestley
English chemist, natural philosopher, separatist theologian, grammarian, multi-subject educator, and liberal political theorist who published over 150 works.
English chemist, natural philosopher, separatist theologian, grammarian, multi-subject educator, and liberal political theorist who published over 150 works.
Priestley is credited with his independent discovery of oxygen by the thermal decomposition of mercuric oxide, having isolated it in 1774.