1Any of the elements fluorine, chlorine, bromine, iodine, and astatine, occupying group VIIA (17) of the periodic table. They are reactive non-metallic elements which form strongly acidic compounds with hydrogen from which simple salts can be made.
- For many syntheses, this means using such compounds as hydrocarbons and alcohols, plus inorganic acids, metals, halogens, or other compounds.
- The oxidation number of the halogens other than fluorine is - 1, unless they are bonded to oxygen or a more electronegative halogen.
- Four important chemical family names of elements still widely used are the alkali metals, the alkaline earths, the halogens, and the noble gases.
1.1 [as modifier] Denoting lamps and radiant heat sources using a filament surrounded by the vapour of iodine or another halogen: a halogen bulb
More example sentences
- The light source was a halogen lamp and light intensity was varied with neutral density filters.
- The light source was a microscope halogen lamp, which unilaterally illuminated the protruding stump, via a light guide at a site 2-4 cm from the lower cut end.
- In this treatment, the patient is secured to a dentist chair with leather straps and an extremely hot halogen lamp is left inches from their face for hours at a time.
- Example sentences
- A live television camera and halogenic headlights allow positive identification of the target prior to detonation.
- Association of halogenic minerals here is very poor: it consists of gypsum, calcite and sepiolite.
- Volcanogenous rocks are found among halogenic formations so commonly that they, together with anhydrite, gypsum and limestone, may be considered as component part of these formations.
Mid 19th century: from Greek hals, halo- 'salt' + -gen.
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