1. Atmosphere is the column of air which is extending several hundred kilometers above the surface the Earth's surface. The density of this air decreases as you proceed up from the surface. The air in the atmosphere consists of 78 % nitrogen, 21 % oxygen, and 0.9 % argon. The remaining 0.1 % of the atmosphere consists of ozone, water vapor, carbon dioxide, methane, helium, and neon. The atmosphere is divided into different regions. The lowest two layers are the troposphere (the layer closest to the earth) and the stratosphere respectively. These two layers contain more than 99 % of the atmospheric molecules.
2. Standard atmosphere (atm) is an obsolete pressure and stress unit which should be discontinued. It is unit of pressure equal to the air pressure measured at mean sea level.
1 atm = 101 325 Pa
Technical atmosphere (at) is an obsolete MKpS pressure and sttress derived unit.
1 at = 98 066.5 Pa
1 atm = 1.033 227 453 at
Barometer is an instrument that measures atmospheric pressure. A mercury barometer is a closed tube filled with mercury inverted in a mercury reservoir. The height of the mercury column indicates atmospheric pressure (with 1 atm = 760 mm of mercury). An aneroid barometer consists of an evacuated container with a flexible wall. When atmospheric pressure changes, the wall flexes and moves a pointer which indicates the changing pressure on a scale.
Chemical balance is a degree of reversible reaction in a closed system, when the forward and backward reaction happen at same rates and their effects annul each other, while the concentration of reactants and products stays the same.
Combustion is a phenomenon when a substance is combined with oxygen in the presence of a flame accompanied by the production of heat and light. Combustion requires a supply of both fuel and oxygen (air) and can take place in the open atmosphere such as an open fire, or in a closed system, such as a car engine.
Computational chemistry is a branch of chemistry concerned with the prediction or simulation of chemical properties, structures, or processes using numerical techniques.
Beta-glucans are are naturally occurring polysaccharides that contain only glucose as structural components, and are linked with β-glycosidic bonds. They is the most known powerful immune stimulant. The most active forms of β-glucans are those comprising D-glucose units with β(1→3) links and with short side-chains of D-glucose attached at the β(1→6) position. These are referred to as beta-1,3/1,6 glucan. They are a major component of soluble dietary fiber, which can be found in cereal grains (oats, barley, wheat), yeast, and certain mushrooms (shiitake, maitake).
Body-centered cubic lattice (bcc or cubic-I), like all lattices, has lattice points at the eight corners of the unit cell plus an additional points at the center of the cell. It has unit cell vectors a = b = c and interaxial angles α=β=γ=90°.
The simplest crystal structures are those in which there is only a single atom at each lattice point. In the bcc structures the spheres fill 68 % of the volume. The number of atoms in a unit cell is two (8 × 1/8 + 1 = 2). There are 23 metals that have the bcc lattice.
Borane is any of the group of compounds of boron and hydrogen (B2H6, B4H10, B5H9, B5H11...), many of which can be prepared by action of acid on magnesium boride (Mg3B2). Boranes are a remarkable group of compounds in that their structures cannot be described using the conventional two-electron covalent bond model.
Bunsen burner is a standard source of heat in the laboratory. German chemist Roberts Bunsen (1811-1899) improved the burner's design, which had been invented by Faraday, to aid his endeavors in spectroscopy. The Bunsen burner has a vertical metal tube through which a fine jet of fuel gas is directed. Air is drawn in through airholes near the base of the tube and the mixture is ignited and burns at the tube’s upper opening. The flow of this air is controlled by an adjustable collar on the side of the metal tube. When the whole is closed a yellow safety flame is displayed. Where as when the whole is open it displays a power dull blue flame with a faint blue outer flame with a vibrant blue core used u for combustion and hearting. The flame can reach temperatures of 1 500 °C.
Generalic, Eni. "Hexagonal close-packed structure." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
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