CHEMISTRY GLOSSARY

ice    →   led

Ice is a solid form of water. Water expands when it freezes due to hydrogen bonds thus making ice less density than water so it floats on it.

ideal gas    →   idealni plin

Ideal gas is a gas in which there is complete absence of cohesive forces between the component molecules; the behaviour of such a gas can be predicted accurately by the ideal gas equation through all ranges of temperature and pressure. The concept is theoretical, since no actual gas meets the ideal requirement.

insulator    →   izolator

Insulator is a material in which the highest occupied energy band (valence band) is completely filled with electrons, while the next higher band (conduction band) is empty. Solids with an energy gap of 5 eV or more are generally considered as insulators at room temperature. Their conductivity is less than 10^-6 S/m and increases with temperature.

deoxyribonucleic acid    →   dezoksiribonukleinska kiselina

Deoxyribonucleic acid (DNA) is a nucleic acid with 2-deoxy-D-ribose as the sugar in its nucleotides. DNA contains encoded genetic information, specifically templates for the synthesis of all of an organism’s proteins and enzymes.

DNA was first identified in the 1869 by Swiss chemist Friedrich Miescher (1844-1895). In 1953, American biologist James Dewey Watson (1928-) and English physicist Francis Harry Compton Crick (1916–2004) had discovered that DNA occurs in the cell as a double helix, with two long strands of the molecule wound around each other, and further that the chemical structure of the molecule dictates that adenine (A) always aligns or pairs with thymine (T), and cytosine (C) always pairs with guanine (G). It is this base pairing that allows DNA in a cell to copy itself, and transfer its information to a new cell. The diameter of the helix is 2.0 nm and there is a residue on each chain every 0.34 nm in the z direction. The angle between each residue on the same strand is 36°, so that the structure repeats after 10 residues (3.4 nm) on each strand.

diagenesis    →   dijageneza

Diagenesis is the process that turns sediments into sedimentary rocks. The lithification (literally turning into stone) of the sediments is usually accomplished by a cementing agent. How the weight of the overlying material increases the grains closer together, reducing pore space and eliminating some of the contained water. This water may carry mineral components in solution, and these constituents precipitate as new minerals in the pore spaces. This causes cementation, which will then start to bind the individual particles together. Further compaction and burial may cause recrystallization of the minerals to make the rock even harder.

isomer    →   izomer

Isomers are compounds that have identical molecular formulae but differ in the nature or sequence of bonding of their atoms (structural isomerism) or in the arrangement of their atoms in space (stereoisomerism).

Lewis acid    →   Lewisova kiselina

Lewis acid is an agent capable of accepting a pair of electrons to form a coordinate bond.

Lewis base    →   Lewisova baza

Lewis base is an agent capable of donating a pair of electrons to form a coordinate bond.

dipole molecule    →   dipolna molekula

Dipole molecules are created when mutual electronic pair at covalent bond is asymmetrical. If different atoms are bonded by a covalent bond, which can have different electron affinity, then the the atom with greater electron affinity will attract the electron pairs more strongly. In this way an asymmetrical distribution of negative charge appears in a molecule, so one part of the molecule becomes relatively negatively (the one closer to the electron pair) and the other becomes relatively positively charged.

dipole moment    →   dipolni moment

Electric dipole moment (μ) is a product of the positive charge and the distance between the charges. Dipole moments are often stated in debyes; The SI unit is the coulomb metre. In a diatomic molecule, such as HCl, the dipole moment is a measure of the polar nature of the bond; i.e. the extent to which the average electron charges are displaced towards one atom (in the case of HCl, the electrons are attracted towards the more electronegative chlorine atom). In a polyatomic molecule, the dipole moment is the vector sum of the dipole moments of the individual bonds. In a symmetrical molecule, such as tetrafluoromethane (CF₄) there is no overall dipole moment, although the individual C-F bonds are polar.