# Why are higher generation of matter unstable?

My secondary school physics textbook has mentioned that protons and neutrons are made up of down and up quarks in different amounts. It has also mentioned that other quarks exist. It states that particles from these quarks are unstable. It also lists the charges of these quarks. It doesn't provide much more detail beyond this. My question is this:

Why is (for example) a particle made up of ccs (Wikipedia tells me this is called a Double charmed Omega baryon) any less stable than a proton which has the same charge?

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Good point. That's a $\Delta^{++}$ baryon and it's more massive than the allowed end state of a proton + pion, which it quickly decays into. The mass of a composite particle is not simply the sum of the mass of its constituents -- most of the mass actually comes from the mass-energy of the strong interaction between the quarks. –  dbrane May 24 '11 at 13:46