Why does ionization energy increase across a period

 effective nuclear charge increases as electron shielding remains constant. ... The increased distance weakens the nuclear attraction to the outer-most electron, and is easier to remove (requires less energy).

Explanation:

In general, ionization energy increases across a period and decreases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant. ... The increased distance weakens the nuclear attraction to the outer-most electron, and is easier to remove (requires less energy).

electrons

Explanation:

more electrons hold the valence electrons more tightly to the nucleus

valence electrons are the electrons on the outer most ring in the electron cloud

asking the goog might u get an answer

we can conclude that the melting point of table salt is above room temperature (it's actually 801 deg c). the melting point of mercury must be below room temperature (- 39 deg c).