* In the Periodic Table: Metals generally appear on the left side and nonmetals on the right. However, this isn't a strict order. There's a "staircase" line separating them, with metalloids (elements with properties of both) bordering the line.
* Formation: The earliest elements formed in the universe were primarily hydrogen and helium (nonmetals). Over time, heavier elements, including metals, were created through nuclear fusion in stars. So, in a cosmological sense, nonmetals came first.
* Chemical Reactions: It's impossible to say one always comes "first" in chemical reactions. Metals and nonmetals can combine to form compounds in many ways, and the order of their interaction depends on the specific reaction.
In short, there's no definitive answer. It depends on what aspect you're considering.
