sodium and helium
a chemical bond
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.
Two or more elements combined chemically is a compound and the smallest unit is a molecule.
Nickel is one of the less chemically active metals. It does not easily combine with other elements.
When atoms of two different elements chemically combine, they produce a compound. Such compounds include sodium chlorine, hydrogen fluorine, and barium sulfide. Note that if the elements are same, the result is a polyatomic element, not a compound.
These elements will not combine chemically.
compound is when two or more elements combine chemically
Elements chemically combine to make molecules.
Their chemical composition
No. helium is chemically inert and does not combine with other elements.