§10-2碱金属元素及其化合物 Alkali metals and their compounds Lithium Sodium Potassium Na K Rubidium Cesium Francium Rb Cs Fr§10-2碱金属元素及其化合物 Alkali metals and their compounds Lithium Sodium Potassium Li Na K Rubidium Cesium Francium Rb Cs Fr