CHEMISTRY GLOSSARY

absolute volume    →   apsolutni volumen

Absolute volume is the total volume of the particles in a granular material, including both permeable and impermeable voids but excluding spaces between particles.

accelerator    →   akcelerator

Accelerator is a device (machine) used for acceleration of charged particles (protons, deuterons, α-particles). Particles are accelerated under the influence of an electric field and with the help of a magnetic field are kept inside a certain space. When the particles reach enough acceleration (that is sufficient energy), they are directed on a target we wish to bomb. Best known types cyclotron, synchrotron, betatron.

Accelerator is a substance that increases the rate of chemical reaction, i.e. a catalyst.

activity    →   aktivitet

Activity (a) is a thermodynamic function used in place of concentration in equilibrium constants for reactions involving nonideal gases and solutions. For the species i activity is defined as

where a_i is the activity of the species i, c_i is its molar concentration, and f_i is a dimensionless quantity called the activity coefficient.

aerosol    →   aerosol

Aerosols are colloidal dispersions of liquid or solid particles in a gas, as in a mist or smoke. The commonly used aerosol sprays contain an inert propellant liquefied under pressure. The pressure of the gas causes the mixture to be released as a fine spray (aerosol) or foam (aerogel) when a valve is opened.

alpha rays    →   alfa-zrake

Alpha rays are a stream of alpha particles. Alpha rays rapidly dissipate their energy as they pass through materials. They were discovered by the British physicist Ernest Rutherford (1871-1937), a New Zealander by birth, in 1903.

antiparticle    →   antičestica

Antiparticle is a particle having the same mass as a given elementary particle and a charge equal in magnitude but opposite in sign.

Avogadro, Amadeo    →   Avogadro, Amadeo

Amadeo Avogadro (1776-1856) is an Italian chemist and physicist that proposed a correct molecular explanation for Gay-Lussac’s law of combining volumes. His work provided a simple way to determine atomic weights and molecular weights of gases. He is published a theory about the movement of particles in gases that became known as Avogadro’s Law.

astatine    →   astat

Astatine was discovered by Emilio Gino Segrè, Dale R. Corson and K. R. MacKenzie (USA) in 1940. The origin of the name comes from the Greek word astatos meaning unstable. It is unstable, radioactive member of the halogen group. Astatine does not occur in nature. Similar to iodine. Produced by bombarding bismuth with alpha particles. Since its isotopes have such short half-lives there are no commercially significant compounds of astatine.

atom    →   atom

Atom is an atom is the smallest particle of an element that retains the chemical properties of the element. Rutherford-Bohr’s model represents the atom as a positively charged core of a size around 10^-14 m composed of protons (positive particles) and neutrons (neutral particles) around which negatively charged electrons circle. The number of protons and electrons are equal, so the atom is an electrically a neutral particle. Diameter of the atom is about 10^-10 m.

bag filter    →   vrećasti filtar

Bag filter is a unit within a mechanical system that bellows in a bag form when air flows through, cleaning the air by collecting particles of foreign matter. This system of filtering is rated the most efficient- in a range of 92 % to 95 %. Vacuum cleaner have a cloth filter bag.

Bag filter system is an economical method of liquid filtration consisting of the pressure vessel, restrainer basket and micron rated filter bag. Liquid flow is from the inside to the outside of the bag - dirt is trapped inside the bag.