La
元素符号:La
中文名称:镧
英文名称:Lanthanum
原子序数:57
原子量:138.9
外围电子排布:5d1 6s2
核外电子排布:2,8,18,18,9,2
常见化合价:+3
密度:6.7
溶点:918
沸点:3464
所属周期:6
所属族数:IIIB
原子半径:2.74
离子半径:1.18(+3)
共价半径:1.69
同位素及放射性:La-138(放 εβ) *La-139
发现人:Carl Mosander
发现时间:1839
发现地点:瑞典
名称由来:Greek: lanthanein (to be hidden).
元素描述:Soft, silvery-white, malleable, ductile metal.
元素来源:Found with rare earths in monazite and bastnasite. Monazite sand typicall contains 25% lanthanum.
元素用途:It is used in the electodes of high-intensity, carbon-arc lights. Also used in the production of high-grade europium metal. Because it gives glass refractive properties, it is used in expensive camera lenses.
