Across the period the size of an atom decreases and effective nuclear charge​

Atomic radius decreases across a period and increases down a group. Across a period, effective nuclear charge increases as electron shielding remains constant. Down a group, the number of energy levels (n) increases, so there is a greater distance between the nucleus and the outermost orbital.

Explanation:

the number of protons in the nucleus of a given element. has slight luster and conducts electricity at high temperatures like metal.but like a nonmetal,boron is brittle and does not conduct electricity well at low temperatures. in graphite, carbon is a soft,brittle solid.it is reflective,ductile,or malleable.

since electrons are negative the answer is neagtaive