题目

Technology is making life easier for some dairy farmers. They use robotic systems to milk their cows. Cows are trained to follow a series of paths that lead to milking stations. Only one cow at a time can enter a station. Once inside，the cow is rewarded with food. As the cow eats，a robotic arm cleans and connects the animal to the milking machine. A few minutes later，milking is complete. The gate is opened，the cow is released and the next cow enters. The robotic systems are designed to operate 24 hours a day. The cows get to decide when they want to be milked. Cows are milked an a 下表为元素周期表的部分元素的相关信息，利用下表回答相关问题。 (1)写出13号元素的名称          ，16号元素的原子最外层电子数是        ， 17号元素的原子在化学变化中容易         (填“得到”或“失去”)电子。 (2)以上元素中与He化学性质相似的元素有          (写一种)。 (3)1、8、1l号元素组成碱的俗名是          。 (4)研究表明：第二周期从3～9号元素的原子电子层数相同，核电荷数逐渐增大，核对核外电子的引力逐渐增大，故原子半径逐渐减小。从而分析第三周期从11～17号元素原子半径变化规律是                                                  。