Answer:
large atomic size and low ionization energy.
Step-by-step explanation:
Metallic behavior correlates with large atomic size and low ionization energy. Thus, metallic behavior increases down a group and decreases from left to right across a period. Elements in Groups 1A(1) and 2A(2) are strong reducing agents; nonmetals in Groups 6A(16) and 7A(17) are strong oxidizing agents.