갈륨 (Ga)

발견 과정

발견: 1875 · Paul-Émile Lecoq de Boisbaudran

갈륨이 발견되기 전, 멘델레예프는 당시 알려진63개 원소 주기율을 발견하고 그 연관성을 주기율표로 정리하다가 빈칸에 들어갈 원자량과 성질을 예측하였다. 그는 이 원소가 주기율표에서 알루미늄 아래에 있다고 하여 이 원소를 에카-알루미늄(eka-aluminum)이라 불렀다. 6년 뒤인1875년에 에카-알루미늄이 발견되었는데, 이 원소가 갈륨이다. 갈륨은 프랑스 화학자 부아보드랑이 처음으로 분리 및 발견했다.

용도와 활용

Organogallium compounds are of similar reactivity to organoindium compounds, less reactive than organoaluminium compounds, but more reactive than organothallium compounds. Alkylgalliums are monomeric. Lewis acidity decreases in the order Al > Ga > In and as a result organogallium compounds do not form bridged dimers as organoaluminium compounds do. Organogallium compounds are also less reactive than organoaluminium compounds. They do form stable peroxides. These alkylgalliums are liquids at room temperature, having low melting points, and are quite mobile and flammable. Triphenylgallium is monomeric in solution, but its crystals form chain structures due to weak intermolecluar Ga···C interactions. Gallium trichloride is a common starting reagent for the formation of organogallium compounds, such as in carbogallation reactions. Gallium trichloride reacts with lithium cyclopentadienide in

동위원소

Gallium has 30 known isotopes, ranging in mass number from 60 to 89. Only two isotopes are stable and occur naturally, gallium-69 and gallium-71. Gallium-69 is more abundant: it makes up about 60.1% of natural gallium, while gallium-71 makes up the remaining 39.9%. All the other isotopes are radioactive, with gallium-67 being the longest-lived (half-life 3.2617 days). Isotopes lighter than gallium-69 usually decay through beta plus decay (positron emission) or electron capture to isotopes of zinc, while isotopes heavier than gallium-71 decay through beta minus decay (electron emission), possibly with delayed neutron emission, to isotopes of germanium. Gallium-70 can decay both ways, to zinc-70 or to germanium-70. Gallium-67 and gallium-68 (half-life 67.84 min) are both used for imaging in nuclear medicine (see gallium scan).