Question

why do metals have high melting points? they dont the negatively charged electrons act as a glue to hold the positively charged ions together. all the electrons become delocalised

Explanation:

Metals have high melting points because of metallic bonding. In metallic bonding, electrons are delocalized. The negatively - charged electrons act as a "glue" (metallic bond) that holds the positively - charged metal ions together. A high amount of energy is required to break these strong metallic bonds, which results in high melting points. The statement "They don't" is incorrect as metals do have high melting points (in general, except for some like mercury which has a relatively low melting point but still due to metallic bonding nature). The statement "All the electrons become delocalised" is a part of the metallic bonding description but the more comprehensive reason related to melting point is the role of these delocalised electrons (acting as a glue) in holding the ions together.

Answer:

The correct explanation is "The negatively charged electrons act as a glue to hold the positively charged ions together."