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 from top to bottom within a group. the measure of an atoms attraction to electrons; generally increases from left to right within a period and decreases from top to bottom within a group.

Explanation:

1. Atomic radius refers to the "size" of the atom, increasing from top - to - bottom in a group and decreasing from right - to - left in a period.
2. Ionization energy is the energy needed to remove an electron from an atom, increasing from left - to - right in a period and decreasing from top - to - bottom in a group.
3. Electronegativity is the measure of an atom's attraction to electrons, increasing from left - to - right in a period and decreasing from top - to - bottom in a group.

Answer:

For the first description "The 'size' of the atom...": Atomic Radius
For the second description "The amount of energy needed to remove an electron from an atom...": Ionization Energy
For the third description "The measure of an atom's attraction to electrons...": Electronegativity