CHEMISTRY GLOSSARY

valence    →   valencija

Valence is the charge on an ion based on the number of electrons transferred or shared within a specific structure. For example, in H₂O, oxygen has a valence of 2, carbon in CH₄ has a valence of four.

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voltametry    →   voltametrija

Voltametry is a common name for a large group of instrumental techniques which are based on measuring the electric current formed by a continuous potential shifting on the electrodes.

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hexagonal crystal system    →   heksagonski kristalni sustav

Hexagonal crystal system is based on four crystallographic axes. The system of crystallographic axes of the hexagonal crystal system consists of three equivalent horizontal (equatorial) axes of which the positive ends make an angle of 120°. These axes are sometimes denoted as a, b and d axes. The fourth axis is (c) is perpendicular to and shorter or longer than the other three.

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histidine    →   histidin

Histidine is an electrically charged amino acids with basic side chains. It is an essential amino acid, which means that humans cannot synthesize it, so it must be ingested. Histidine is perhaps the most common and versatile catalytic residue in proteins. The imidazole sidechain of histidine has a pKa of approximately 6.0. This means that, at physiologically relevant pH values, relatively small shifts in pH will change its average charge. The unprotonated imidazole is nucleophilic and can serve as a general base, while the protonated form can serve as a general acid. In addition, it is often a ligand for transition metal ions such as iron and zinc.

• Abbreviations: His, H
• IUPAC name: 2-amino-3-(1H-imidazol-5-yl)propanoic acid
• Molecular formula: C₆H₉N₃O₂
• Molecular weight: 155.15 g/mol

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white light    →   bijela svjetlost

White light is a mixture of lights of all colours. If white light is passed through a glass prism or an optical lattice, it is separated into several colours (the visible light spectrum).

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indicator    →   indikator

Indicator is a substance used to show the presence of a chemical substance or ion by its colour. Acid-base indicators are compounds, such as phenolphtaleine and methyl orange, which change colour reversibly, depending on whether the solution is acidic or basic. Oxidation-reduction indicators are substances that show a reversible colour change between oxidised and reduced forms.

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international system of units    →   međunarodni sustav jedinica

International System of Units (SI) is the unit system adopted by the General Conference on Weights and Measures in 1960 and recommended for use in all scientific and technical fields. It consists of seven base units (meter, kilogram, second, ampere, kelvin, mole, candela), plus derived units and prefixes.

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kelvin    →   kelvin

Kelvin (K) is the SI base unit of thermodynamic temperature.

The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water. The unit was named after the British scientist Sir. W. Thompson, Lord Kelvin (1824-1907).

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kilogram    →   kilogram

Kilogram (kg) is the SI base unit of mass; it is equal to the mass of the international prototype of the kilogram.

The prototype of the standard is a cylinder of platinum-iridium alloy (90:10), 39 mm in diameter and 39 mm high. Prototype of the kilogram kept by the Bureau International des Poids et Mesures (International Bureau of Weights and Measures) at Sèevres, near Paris.

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lanthanum    →   lantan

Lanthanum was discovered by Carl Gustaf Mosander (Sweden) in 1839. The origin of the name comes from the Greek word lanthanein meaning to lie hidden. It is soft, silvery-white, malleable, ductile metal. Readily tarnishes in air. Reaction with water releases hydrogen gas. Metal ignites and burns readily. Reacts with oxidants. Lanthanum is found with rare earths in monazite and bastnasite. Monazite sand typical contains 25 % lanthanum. It is used in the electrodes of high-intensity, carbon-arc lights. Because it gives glass refractive properties, it is used in expensive camera lenses.

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