Why does a high temperature have to be used to weld pieces of metal together

because of the metling point of metals, it is difficult to just simply put metal together and have them to stay together without any type of glue or epoxy based creams.

wielding is used to melt the surface or even change the compound completely so they are able to combine with other metals.

same thing with atoms, you need a lot of heat, and speed to simply make salt or even copper because of the elements not really being favorable of each other.

what are the óptions. pléase list them

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.