X和Y是原子序数大于4的短周期元素,Xm+和Yn-两种离子的核外电子排布相同,下列说法中,正确的是( )
A:X的原子半径比Y小
B:X和Y的核电荷数之差为m-n
C:电负性:X>Y
D:第一电离能:X<Y
Could you record today's NBA basketball game for me? I can watch later.