A basic betterworld2016.orgistrybetterworld2016.orgTextmaporganized about the textbookbetterworld2016.orgistry: Principles, Patterns, and Applicationsby Bruce A. Averill


Learning Objectives

To know the periodic trends and reactivity of the group 17 elements: the halogens.

You are watching: What is group 7a on the periodic table

Because the halogens are highly reactive, no one is uncovered in nature as the free element. Hydrochloric acid, i beg your pardon is a ingredient of aqua regia (a mixture of HCl and HNO3 that dissolves gold), and the mineral fluorspar (CaF2) were well known to albetterworld2016.orgists, who supplied them in their search for gold. In spite of their existence in acquainted substances, none of the halogens was even recognized as an facet until the 19th century.

Because the halogens are highly reactive, nobody is found in nature as the free element.

Chlorine to be the very first halogen come be obtained in pure form. In 1774, Carl Wilhelm Scheele (the codiscoverer of oxygen) produced chlorine by reacting hydrochloric acid v manganese dioxide. Scheele to be convinced, however, the the pale environment-friendly gas he collected over water to be a link of oxygen and also hydrochloric acid. In 1811, Scheele’s “compound” was determined as a new element, named from the Greek chloros, definition “yellowish green” (the very same stem as in chlorophyll, the environment-friendly pigment in plants). That very same year, a French industrial betterworld2016.orgist, young name Courtois, accidentally included too lot sulfuric acid to the residue obtained from burned seaweed. A deep violet vapor to be released, which had a biting aroma comparable to the of Scheele’s “compound.” The violet substance was identified as a brand-new element, called iodine native the Greek iodes, an interpretation “violet.” Bromine was found soon after by a young French betterworld2016.orgist, Antoine Jérôme Balard, who isolated a deep red liquid with a solid chlorine-like odor from brine native the salt marshes close to Montpellier in southern France. Due to the fact that many of its properties were intermediate between those the chlorine and also iodine, Balard originally thought he had isolated a compound of the 2 (perhaps ICl). He soon realized, however, that he had uncovered a new element, i beg your pardon he named bromine native the Greek bromos, definition “stench.” Currently, organic chlorine compounds, such as PVC (polyvinylchloride), consume around 70% the the Cl2 developed annually; organobromine link are provided in lot smaller quantities, primarily as fire retardants.

A crystal of the mineral fluorite (CaF2). The purple shade of part fluorite crystals is due to small inclusions of very oxidizing impurities, which create detectable quantities of ozone once the crystals room crushed.

See more: How Big Is A Dasani Water Bottle S, 12 Fl Oz, 8 Pack, Dasani Purified Water Bottles, 12 Fl Oz, 8 Pack

Because that the distinctive properties of its compounds, fluorine was thought to exist long prior to it was actually isolated. The mineral fluorspar (now called fluorite ) had actually been used because the 16th century together a “flux,” a low-melting-point substance that could dissolve other minerals and also ores. In 1670, a German glass cutter found that heater fluorspar with strong acid created a solution that might etch glass. The equipment was later recognized to save on computer the acid of a brand-new element, which was called fluorine in 1812. Elemental fluorine confirmed to be very daunting to isolate, however, because both HF and also F2 room extraordinarily reactive and also toxic. After being poisoned three times when trying to isolation the element, the French betterworld2016.orgist Henri Moissan thrived in 1886 in electrolyzing a sample the KF in anhydrous HF to produce a pale environment-friendly gas (Figure \(\PageIndex1\)). For this achievement, among others, Moissan narrowly beat Mendeleev for the Nobel compensation in betterworld2016.orgistry in 1906. Huge amounts of fluorine are currently consumed in the manufacturing of cryolite (Na3AlF6), a key intermediate in the production of aluminum metal. Fluorine is also found in teeth as fluoroapatite , which is created by reacting hydroxyapatite in this enamel v fluoride ions in toothpastes, rinses, and also drinking water.

22.14.jpgwhat is group 7a on the periodic table