Helium, He, is a nonmetallic gas and the second element in the periodic table. Rather than being placed adjacent to hydrogen, H, however, helium is placed on the far right of the table because
A) hydrogen and helium repel one another.
B) the sizes of their atoms are vastly different.
C) they come from different sources.
D) helium is most similar to other group 18 elements.
Question 2
Strontium, Sr (number 38), is especially dangerous to humans because it tends to accumulate in calcium-dependent bone marrow tissues (calcium, Ca, number 20).
This fact relates to the organization of the periodic table in that strontium and calcium are both
A) metals.
B) in group 2 of the periodic table.
C) made of relatively large atoms.
D) soluble in water.