What Are the Building Blocks of Matter?

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The fundamental building blocks of matter are particles called quarks and leptons. There are six different types of quarks and six different types of leptons. Scientists classify the various types of quarks and leptons into different generations. Each generation contains two quarks and two leptons. The lightest and most stable particles form the first generation, and each subsequent generation contains heavier and less stable particles.

Scientists call the first generation of quarks the “up” and “down” quarks. They call the second generation of quarks the “strange” and “charm” quarks, while the third generation of quarks are the “top” quark and the “bottom” quark. Physicists classify leptons similarly, naming the first generation the “electron” and the “electron neutrino.” The second generation of leptons are called the “mau” and “mau neutrino,” while the “muon” and “muon neutrino” comprise the third generation. The neutrino in each pair lacks significant mass and electric charge, while the corresponding mau, muon and electron do possess considerable mass and electric charge.

All of these fundamental particles combine to form atoms, which in turn form molecules, which combine to form the various substances with which humans are familiar. Physicists first predicted the existence of such particles in the early 1970s as they created something called the “Standard Model.” Thousands of experiments in subsequent decades have shown that the basic predictions of the model are correct.