Is carbon a metallic element?
No, it is non-metallic.
If a non-metallic element (eg. oxygen) and a metallic element (Magnesium) combine, an ionic compound is formed. (eg. Magnesium Oxide) If a non-metallic element (eg. Carbon) and a non-metallic element (Oxygen) combine, a co-valent compound is formed. (eg. Carbon Dioxide) So basically, its just about what kind of elements you're referring to. But usually, a compound would be formed.
What is an element whose atoms can form a covalent bonds with another atom of the same element called?
yes, brass is a alloy and zinc is a element. metallic elements are usually weaker than alloys because the atoms of a metal CAN slide through each other while this allows bending of a metallic element quite easy (e.g. aluminum foil (Al) can be bent easily) and since most alloys contain carbon atoms, the carbon atom will make it harder for the alloy's metallic atoms to slide through each other and hence giving it's strength…
The color of carbon depends on the form it takes. Most of the time carbon is black, but when it forms graphite it is gray with a bit of a metallic luster. In the form of diamonds carbon is often transparent. The element carbon can be transparent as in a diamond and dark gray as graphite, and it can also be a gas.
CO is Carbon Oxide or carbon and oxygen. They are bonded in a compound. Co is Cobalt. Cobalt is a hard ferromagnetic silver-white bivalent or trivalent metallic element. An element is a pure substance that doesn't contain anything but itself. For example H (Hydrogen) is an element but H2O (Water) is not (it is a compound).