可唔可以解釋下effective nuclear charge係咩?first ionisation energy係咩?
同埋點解個trend有分別
兩樣野都out syl架wor
effective nuclear charge(有效核電荷)即係扣減左inner electron shell既blocking後outermost electron真正feel到既nuclear charge(proton既positive charge)
因為inner electron shell會令nucleus同outermost electron之間既吸引力減弱(shielding effect屏蔽效應)
呢樣野通常用黎解釋periodic table由左至右一行(e.g. Na -> Ar)個atomic radius會decrease既trend
first ionisation energy(第一電離焓)係指要令一粒atom remove佢一粒outermost shell electron時所需既能量
即係 A -> A+ + e- 既enthalpy change
而由於唔同既atom有唔同electronic arrangement
有d元素會比較易甩電子 例如Na 2,8,1
咁就需要少量能量就ionize到1e-
個first ionisation energy會低d
而有d元素佢本身outermost shell係full filled (or half filled for transition elements)
咁就會好穩定 -> 難甩電子
個first ionisation energy會偏高
例如Ar 2,8,8