CHEMISTRY GLOSSARY

triclinic lattice    →   triklinska rešetka

Triclinic lattice has one lattice point at the each corner of the unit cell. It has unit cell vectors a≠b≠c and interaxial angles α≠β≠γ≠90°.

bcc    →   bcc

bcc is abbreviation for body-centered cubic lattice.

chiral centre    →   kiralno središte

Chiral centre in organic chemistry is most often an asymmetrically substituted carbon atom (C^*).

angular velocity    →   kutna brzina

A point-like object that undergoes circular motion changes its angular position from initial Θ_i to final Θ_f, relative to a fixed axis, specified in a coordinate system with an origin that coincides the centre of the circular path of object. The change in its angular position is called angular displacement ΔΘ = Θ_f - Θ_i. Also, a rigid body that rotates about a specified rotation axis, changing its angular position from initial Θ_i to final Θ_f, undergoes an angular displacement ΔΘ.

The average angular velocity, ω_av, is the ratio of the angular displacement and the time interval Δt=t_f-t_i, in which that displacement occurs.

Θ_f and Θ_i are the initial and final angular position, respectively.

The instantaneous angular velocity ω is the limit of the average angular velocity, as Δt is made to approach zero.

ω_av and ω are positive for the counterclockwise rotation (in direction of increasing Θ) and negative for the clockwise rotation (in direction of decreasing Θ).

SI unit for angular velocity is s^-1.The measure for the angle Θ is radian. The relationship between radians and degrees is:

For example, the angular velocity of the minute hand of a clock is:

centrifugal force    →   centrifugalna sila

Centrifugal force is a force which moves a body away from the centre of motion.

centripetal force    →   centripetalna sila

Centripetal force is a force which makes body move through a curvature. Its orientation is always in path forwards the centre of rotation.

fcc    →   fcc

fcc is abbreviation for face-centered cubic lattice.

mass    →   masa

Mass (m) is the quantity of matter contained in a particle or body regardless of its location in the universe. Mass is constant, whereas weight is affected by the distance of a body from the centre of the Earth (or of other planet). The SI unit is kilogram.

According to the Einstein equation

all forms of energy possess a mass equivalent.

Newton’s gravitational law    →   Newtonov zakon gravitacije

Every object in the universe attracts every other object with a force (gravitational force F_G) directed along the line through centres of the two objects that is proportional to the product of their masses and inversely proportional to the square of the distance between them.

m₁ and m₂ are masses of the two objects and r is the distance between them. G is universal constant of gravitation, which equals 6.67•10^-26 N m² kg^-2. Strictly speaking, this law applies only to objects that can be considered pointlike object. Otherwise, the force has to be found by integrating the forces between various mass elements.

It is more properly to express Newton’s gravitational law by vector equation:

in which r₁ and r₂ are position vectors of masses m₁ and m₂.

Gravitational forces act on distance. Newton’s gravitational law is derived from Kepler’s law for planetary motion, using a physical assumption considering Sun as the centre and the source of gravitational force.

Additionally, every object moves in the direction of the force acting on it, with acceleration that is inversely proportional to the mass of object. For bodies on the surface of Earth, the distance r in gravitational law formula is practically equal to the Earth radius, R_E. If the mass of the body on Earth surface is m and the mass of earth is M_E, the gravitational force acting on that body can be expressed as:

where g is gravitational acceleration which is, although dependent on geographical latitude, usually considered as constant equal to 9.81 m s^-2.

adrenaline    →   adrenalin

Adrenaline was the first naturally produced hormone to be isolated in its pure state. It is known as epinephrine, but its chemical name is 1-[3,4-dihydroxyphenol]-2-methylaminoethanol. Adrenaline is a hormone, produced by the medulla of the adrenal glands, that increases heart activity, improves the power and prolongs the action of muscles, and increases the rate and depth of breathing to prepare the body for "fright, flight, or fight". At the same time it inhibits digestion and excretion.