Can somebody catch me up on subatomic particles?

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When I studied physics and chemistry in school I was taught that atoms are composed of protons, nuetrons, and electrons, and that their interactions can explain chemistry and chemical interactions. Now I understand that this is either wildly oversimplified or wildly out of date. Would somebody be able to catch me up, simply, on what the smallest building blocks of out world are and how they interact to create matter?

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> that atoms are composed of protons, nuetrons, and electrons, and that their interactions can explain chemistry and chemical interactions.

This is basically true. Processes involving any other particles are usually not regarded as falling under the heading of “chemistry”, though the divisions between academic fields are generally a bit fuzzy and arbitrary.

> simply, on what the smallest building blocks of out world are and how they interact to create matter?

There will probably never be a complete answer to this question, because it’s hard to imagine how anyone could ever be confident that they have found all the smallest building blocks.

The smallest known building blocks of ordinary matter are electrons and quarks. Quarks come in several different varieties: they have a “generation” (up, down, charm, strange, top, or bottom) and a “colour” (red, green, or blue). A proton is made up of two up quarks and a down quark (one red, one green, and one blue). A neutron is made up of two down quarks and an up quark (one red, one green, and one blue). Each quark has a corresponding antiquark, so there are also antiprotons and antineutrons. Other combinations of quarks (including single quarks by themselves) are unstable: some of them pop in and out of existence as part of the interactions between particles, while others only show up under high-energy conditions (e.g. particle accelerators and stars).

There are also some heavier electron-like particles, called muons and tau particles, which are also unstable, and all three of these have corresponding antiparticles. Each of these has a corresponding neutrino. Neutrinos have a tiny mass and interact very weakly with other particles, so they are hard to detect.

Then you have photons, which “mediate” the electromagnetic force, eight types of gluons, which play the same role for the strong nuclear force, the Z particle and two types of W particle, which play the same role for the weak nuclear force, and the Higgs particle, which effectively gives mass to some of the other particles. Those three forces – electromagnetism and the strong and weak forces – are how the different particles interact with each other.

It’s considered very likely that there are still some undiscovered particles: the most likely candidates include a “graviton” to mediate gravity, and a “weakly interacting massive particle” that may make up dark matter.

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