✔ 最佳答案
Ionization energy of an element (say X) is the energy required for 1 mole of gaseous atoms of the element to remove 1 mole of electrons to form 1 mole of gaseous singly-charged cations, i.e.
X(g) → X⁺(g) + e⁻ …… ΔH = ionization energy of X > 0
Obviously, no matter whether it is a metal or a non-metal, the greater the ionization of the element, the more difficult for it to lose an electron.
The statement "non-metals and metals react oppositely" means that non-metals tend to gain electrons in reaction but metals tend to lose electrons.