Metals have luster, are malleable and ductile, conduct heat and electricity and may combine with other metals; nonmetals, in contrast, have little or no shine, are neither malleable nor ductile, do not conduct heat or electricity and exist as molecules in their most basic forms. Metals and nonmetals occasionally share overlapping characteristics, particularly elements located proximately on the periodic table of elements. However, most embody these characteristics, which are used to classify and categorize elements into the categories of metals and nonmetals.
Metals are generally abundant elements that have a distinct luster or shine and occur primarily as solids at room temperature. They have various degrees of flexibility: some are soft, while others are much harder. Metals are generally good conductors of heat and electricity and exist as elongated planes of atoms. Metals often attract like elements, which allows them to combine with other metals to form alloys with metallic characteristics. Metals also have the ability to form positive atoms, whereas nonmetals do not. Nonmetals, in contrast, lack metallic luster and primarily exist in gaseous forms at room temperature. They do not conduct heat and electricity and may combine with other nonmetals to form covalent bonds. Nonmetals, like metals, can combine to form different substances: the linking of two or more nonmetals creates negative ions.