Question

the \size\ of the atom; generally increases from top to bottom within a group and decreases from right to left within a period. the amount of energy needed to remove an electron from an atom; generally increases from left to right within a period and decreases

Explanation:

The description given about the property that generally increases from top - to - bottom within a group and decreases from right - to - left within a period matches the trend of atomic radius. Electronegativity generally increases from left to right across a period and from bottom to top within a group. Ionization energy generally increases from left to right across a period and decreases from top to bottom within a group.

Answer:

Atomic Radius