What is the representative particle of potassium?

Answer 1

A representative particle is thought of as the smallest unit into which a substance may be divided without changing its composition. Some examples might be helpful. For a given chemical element, it's an atom. An atom of carbon is the smallest unit of carbon one can find.

For covalently bonded compounds & diatomic molecules, the representative particle is a molecule. For example, an atom of hydrogen and an atom chlorine covalently bond to make a molecule of hydrochloric acid (HCl), and that's the smallest unit of this compound that there is. Because a molecule is a group of 2 or more atoms covalently bonded together, the smallest particles of ionic compounds are the respective ions. For example the smallest particle of the ionic compound sodium chloride (NaCl, or table salt) is a sodium ion (Na+) and a chlorine ion (Cl-).

There is a "scaled up" application in physics and engineering, and it might apply to something like a grain of wheat being the representative particle of that grain crop. A kernel of corn might be the representative particle for that grain crop. A grain of salt might be the representative particle for granular salt as a market commodity. These are important because of considerations regarding density and "close packing" and "voids" in bulk quantities of each commodity. There are more examples of the application of the term if one looks.

A given size granule of an aggregate might be the representative particle for analysis in something like moisture penetration in sand, small pebbles, or chunks of rock.

On the other end of the scale, there are representative particles for certain applications in the physics lab where something like the characteristics of a particle beam may be under consideration. A certain particle of given mass and energy might be the representative particle for, say, the study of particle beam divergence.

Most applications for the student will be in chemistry, and that's where the atom, molecule or, possibly, the ion, will be shown to be the representative particles of an element, a compound, or an electrolytic solution respectively.