CHEMISTRY GLOSSARY

critical mass    →   kritična masa

Critical mass is the minimum mass of a fissionable material (²³⁵U or ²³⁹Pu) that will initiate an uncontrolled chain reaction as in an atomic bomb. The critical mass of pure ²³⁹Pu is about 4.5 kg, and of ²³⁵U about 15 kg.

masking reagent    →   maskirajući reagens

Masking reagent reacts with sample components which can increase the analysis results.

mass number    →   maseni broj

Mass number (A) is a characteristic property of a specific isotope of an element, equal to the sum of the number of protons and neutrons in the nucleus.

mass ratio    →   maseni omjer

Mass ratio is equal to the proportion of the mass of one (m_A) and the mass of other component (m_B).

law of conservation of mass    →   zakon o očuvanju mase

Law of conservation of mass states that no detectable gain or loss in mass occurs in chemical reactions. The state of a substance may change in a chemical reaction, for example, from a solid to a gas, but its total mass will not change. Note that the energy released (exothermic) or adsorbed (endothermic) in a chemical reaction is a result of energy transfer between atoms and their environment.

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.

mass concentration    →   masena koncentracija

Mass concentration (γ) is equal to mass (m_A) of soluted substance and volume (V) of the solution proportion. SI unit for mass concentration is kg m^-3, but in laboratory practice g dm^-3, which has the same number value, is often used.

mass fraction    →   maseni udio

Mass fraction (w_A) is the ratio of the mass of substance A to the total mass of a mixture.

mass spectrometry    →   masena spectrometrija

Mass spectrometry is an analytical technique in which ions are separated according to the mass/charge (m/e) ratio and detected by a suitable detector.

In a mass spectrometer a sample is ionised and the positive ions produced are accelerated into a high-vacuum region containing electric and magnetic fields. These fields deflect and focus the ions onto a detector. A mass spectrum is thus obtained, consisting of a series of peaks of variable intensity to which m/e values can be assigned. Different molecules can be identified by their characteristic pattern of lines.

relative atomic mass    →   relativna atomska masa

Relative atomic mass (A_r) is the ratio of the average mass per atom of the naturally occurring form of an element to 1/12 of the mass of nuclide ¹²C. The term atomic weight is synonymous with the relative atomic mass.