In most cases light can be described as an electromagnetic wave. Geometrical optics is an approximation in which the waves can be represented as straight-line rays. This approximation is valid if the light waves do not meet obstacles comparable in size to the wavelength of radiation.
Bunsen burner is a standard source of heat in the laboratory. German chemist Roberts Bunsen (1811-1899) improved the burner's design, which had been invented by Faraday, to aid his endeavors in spectroscopy. The Bunsen burner has a vertical metal tube through which a fine jet of fuel gas is directed. Air is drawn in through airholes near the base of the tube and the mixture is ignited and burns at the tube’s upper opening. The flow of this air is controlled by an adjustable collar on the side of the metal tube. When the whole is closed a yellow safety flame is displayed. Where as when the whole is open it displays a power dull blue flame with a faint blue outer flame with a vibrant blue core used u for combustion and hearting. The flame can reach temperatures of 1 500 °C.
Cadmium was discovered by Friedrich Strohmeyer (Germany) in 1817. The origin of the name comes from the Latin word cadmia meaning calamine (zinc carbonate, ZnCO3), or from the Greek word kadmeia with the same meaning. It is soft, malleable, blue-white metal. Tarnishes in air, soluble in acids, insoluble in alkalis. Boiling cadmium gives off a weird, yellow-colored vapour that is poisonous. Cadmium can cause a variety of health problems, including kidney failure and high blood pressure. Cadmium is obtained as a by product of zinc refining. The mayor use of cadmium is in electroplating of steel to protect it from corrosion. Also used to make nickel-cadmium batteries. The ability of cadmium to adsorb neutrons has made it of great importance in the design of nuclear reactors. Its compounds are found in paint pigments and a wide variety of intense colours.
Caesium was discovered by Robert Bunsen and Gustav Kirchhoff (Germany) in 1860. The origin of the name comes from the Latin word caesius meaning sky blue or heavenly blue. It is very soft, light grey, ductile metal. Reacts readily with oxygen. Reacts explosively with water. Caesium is found in pollucite [(Cs4Al4Si9O26)·H2O] and as trace in lepidolite. Used as a ’getter’ to remove air traces in vacuum and cathode-ray tubes. Also used in producing photoelectric devices and atomic clocks. Since it ionises readily, it is used as an ion rocket motor propellant.
Holography is a technique for creating a three-dimensional image of an object by recording the interference pattern between a light beam diffracted from the object and a reference beam. The image can be reconstructed from this pattern by a suitable optical system.
When some substance is hygroscopic, it means that that substance can absorb moisture from air.
Irradiation is exposition of food to the action of gamma rays, in order to preserve it longer. It is especially used for fruit.
Red-hot gases give line spectrum, i.e. is they emit electromagnetic rays of defined wavelengths. That kind of emission line of spectrum is characteristic of each chemical element.
Lower flammable limit (LEL) or the lower explosive limit is the minimum concentration of vapour or gas in air above which propagation of flame does not occur on contact with a source of ignition. The mixture is said to be too lean.
Neon was discovered by Sir William Ramsay and Morris W. Travers (England) in 1898. The origin of the name comes from the Greek word neon meaning new. It is colourless, odourless inert gas. Non-reactive even with fluorine. Fourth most abundant element in the universe. Neon is obtained by liquefaction of air and separated from the other gases by fractional distillation. Primarily for lighting.
Generalic, Eni. "X-zrake." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
Glossary
Periodic Table