下列说法正确的是( ) A 基态原子第五电子层只有2个电子,则该原子第四电子层的电子数肯定为8或18个 B 核外电子数为奇数的基态原子,其原子轨道中一定含有未电子 C R为第二周期元素,其原子具有的电子层数为最外层电子数的1/2,它可能形成的含氧酸根离子有 ① RO、② R 2 O、③ RO D Li、Be、B三种元素的第一电离能( I 1 )差别不大,而 I 2 差别很大,则三种原子中最难失去第二个电子的是Be
【单选题】SECTION 1 Directions: Each sentence below has one or two blanks, each blank indicating that something has been omitted. Beneath the sentence are five lettered or sets of words. Choose the word or set ...
【单选题】SECTION 1 Directions: Each sentence below has one or two blanks, each blank indicating that something has been omitted. Beneath the sentence are five lettered or sets of words. Choose the word or set ...
【单选题】SECTION 1 Directions: Each sentence below has one or two blanks, each blank indicating that something has been omitted. Beneath the sentence are five lettered or sets of words. Choose the word or set ...