Quantization of Charge

Worked out. Given water's molecular mass is 18.0 g, so 18.0 g of water contains Avogadro's number ($6.02\times10^{23}$) of molecules, hence 1 g contains $6.02\times10^{23}/18\approx3.34\times10^{22}$ molecules. Each $H_2O$ molecule has 10 electrons (2 from its two hydrogen atoms plus 8 from its one oxygen atom), so the number of electrons (equal to the number of protons, since water is neutral) in 1 g of water is $3.34\times10^{22}\times10\approx3.34\times10^{23}$. Multiplying by the elementary charge, total positive charge $=3.34\times10^{23}\times1.6\times10^{-19}\text{C}\approx5.35\times10^4$ C, exactly balanced by an equal magnitude of negative charge so the water sample as a whole stays electrically neutral -- illustrating just how enormous the amount of charge locked up (but perfectly …

Worked out. Modern particle physics holds that protons and neutrons are themselves built from more fundamental particles called quarks, of six distinct types (flavours), each carrying a FRACTIONAL charge of either $-\frac{1}{3}e$ or $+\frac{2}{3}e$; a proton or a neutron is a bound combination of exactly three quarks. Crucially, this does not break the quantization of charge observed on free particles -- quarks are always confined in bound states and no free (isolated) quark has ever been observed -- it only means the truly fundamental step size of charge is $e/3$ rather than $e$, a refinement invisible at the everyday, free-particle level. The box also notes that in very sensitive modern devices, such as the single-electron transistor, the discrete, one-electron-at-a-time nature of charge CAN …