What are the major differences between metals and non-metals?

Describe the theory associated with the radius of an atom as it

A. gains an electron

B. loses an electron

Would you expect the first ionization enthalpies for two isotopes of the same element to be the same or different? Justify your answer.

Use the periodic table to answer the following questions.

A. Identify an element with five electrons in the outer subshell.

B. Identify an element that would tend to lose two electrons.

C. Identify an element that would tend to gain two electrons.

D. Identify the group having metal, non-metal, liquid as well as gas at the room temperature.

The increasing order of reactivity among group 1 elements is Li < Na < K < Rb <Cs whereas that among group 17 elements is F > CI > Br > I. Explain.