This question already has an answer here:
How come atoms can have such a wide range of appearance, as well as atomic & chemical properties?
At one point you have something invisible & gaseous at room temperature, add a few protons/neutrons/electrons, and you have something solid & shiny. Seems like a huge difference for a small change.
Even within the same element you can have a wide spectrum of properties - carbon for example has a few quite different allotropes (e.g. diamond vs graphite vs Q-carbon).
I'm not so much interested on how these differences arise (e.g. valence electrons), but rather why they are so varied. (Which is why I don't think this is a duplicate of either Do current models of particle physics explain the chemical properties of elements/compounds? or What enables protons to give new properties to an atom every time one is added?)