Absolute zero. Zero kelvin (â273.15 Â°C) is defined as absolute zero. Absolute zero is the lower limit of the thermodynamic temperature scale, a state at which the enthalpy and entropy of a cooled ideal gas reaches its minimum value, taken as 0. Absolute zero is the point at which the fundamental particles of nature have minimal vibrational motion, retaining only quantum mechanical, zero-point energy-induced particle motion. The theoretical temperature is determined by extrapolating the ideal gas law; by international agreement, absolute zero is taken as ...
The nuclear spins for individual protons and neutrons parallels the treatment of electron spin, with spin 1/2 and an associated magnetic moment. The magnetic moment is much smaller than that of the electron. For the combination neutrons and protons into nuclei, the situation is more complicated.
An atom consists of a central nucleus surrounded by an electron cloud. The nucleus is a tightly packed ball made up of protons and neutrons. The mass of the proton and the neutron are nearly the same. The mass of the electron is about 1/2000 of that. The proton has a charge of +1. The neutron has a charge of 0. The electron has a charge of -1. The number of protons in the nucleus is called the atomic number. It tells us what the element is. Hydrogen has one proton, helium has two, lithium three, etc. The number of neutrons gives you the isotope of the given element.