Generally speaking:

First, metals have special metallic luster, most of which are gray, while nonmetallic colors are diverse and complex;

First, metal has a special metallic luster, which is mostly gray, rather than a variety of metals with complex colors;

Secondly, except for mercury, which is liquid at room temperature, other metals are generally solid, and they are heavy and refractory, while many nonmetals are gas or liquid at room temperature;

Second, except for mercury, which is liquid at room temperature, other metals are generally solid, and they are all heavy and difficult to melt, instead of this metal having a lot of gas or liquid at room temperature;

Third, most metals are good at conduction and heat transfer, and nonmetals are often not good at conduction and heat transfer. So many electrical appliances, pots and kettles are made of metal.

Third, most metals are good at conducting heat transfer, and nonmetals are often not good at conducting heat transfer. Therefore, many electrical appliances, pots and pans are made of metal.

Fourth, most metals can be sliced or drawn into filaments, such as tin foil and copper wire, while solid nonmetals are usually brittle.

Fourth, most metals can be laminated or stretched into filaments, such as silver and copper, while solid nonmetals are usually very brittle.

Of course, the above is just "generally speaking", and there is no clear boundary. In fact, many nonmetals are very similar to metals, but some metals have nonmetallic properties. For example, graphite is carbon, not metal, but it has a gray metallic luster like metal and is good at heat and electricity conduction. As for antimony, although it is a metal, it is brittle, not easy to heat and conduct electricity, and has some properties of nonmetal.

Of course, the above is only "in general" and there is no complete boundary. In fact, there are many nonmetals like metals, and some metals have nonmetallic properties. For example, the chemical composition of graphite, carbon, is not a metal, but it has a gray metallic luster and good thermal conductivity like metal, while antimony, although it is a metal, is brittle and difficult to conduct heat, and has some characteristics of nonmetal.

But the fundamental difference between metal and nonmetal is that the resistance of metal increases with the increase of temperature, that is, metal has a positive temperature coefficient of resistance, while the resistance of nonmetal decreases with the increase of temperature, that is, it has a negative temperature coefficient.

But the fundamental difference between metal and nonmetal is that the resistance of metal increases with the increase of temperature, that is, metal has a positive temperature coefficient of resistance, while the resistance of nonmetal decreases with the increase of temperature, that is, it has a negative temperature coefficient.