Calcium. I know because I studied chemistry.
Metals are particularly likely to combine chemically with the halogens you listed, but I will add that almost every element on the periodic table (with the exception of the noble gases) will combine with at least some of the halogens.
sodium and helium
Most of the nonmetals, particularly the halides.
cobalt is very hard, it is most likely for strength and durability
The elements in the family Group 0 - Inert Gases (exc. Radon) will not usually combine with other substances, as this group is highly unreactive. Inert Gases; Helium Neon Argon Krypton Xenon (Radon)
metallic
Metals are particularly likely to combine chemically with the halogens you listed, but I will add that almost every element on the periodic table (with the exception of the noble gases) will combine with at least some of the halogens.
sodium and helium
Fluorine and oxygen
Most of the nonmetals, particularly the halides.
cobalt is very hard, it is most likely for strength and durability
Sodium is one.
Mg (magnesium)
"Element-logy" likely refers to the study of elements, which belong to the periodic table of elements. Elements are substances that cannot be broken down into simpler components and are represented by a unique chemical symbol.
The elements in the family Group 0 - Inert Gases (exc. Radon) will not usually combine with other substances, as this group is highly unreactive. Inert Gases; Helium Neon Argon Krypton Xenon (Radon)
Nobel gasses.
Neon (Ne) and Helium (He)