Introduction to atomic structure

The basic concepts of the electricity we all know and use everyday cannot be fully explained without first having a firm fundamental understanding of the world in which subatomic particles reside and interact. At the core of these concepts lies the structure of an atom.
Nucleus
Within an atom's nucleus reside any number of protons and electrons. Protons are the particles within an atom that hold a positive charge. Neutrons have no electrical charge; they merely contribute to the atomic mass of the atom.
Electrons
Electrons are electric charge, subatomic particles that orbit the atom's nucleus. The nature of electrons is responsible for the flow of electricity, and it is around this atomic component that our study of electricity will revolve.
Atomic Charge
;Hydrogen Atom
The protium hydrogen atom is made up of exactly one proton and one electron. The nucleus of the protium hydrogen atom is a proton, a positively charged particle. The orbiting electron carries a negative charge that is equal in magnitude to the positive charge of the proton. In all other elements, the nucleus also contains neutrons, which are slightly heavier than protons but have no electrical charge.
;Helium Atom
The helium atom usually has two neutrons, two protons, and two electrons. Helium is considered to be a neutral atom because it contains the same number of protons as electrons; therefore, its electrical state is at an equilibrium.
Electron Orbital Shells and Subshells
In general, the electric charge electrons reside in groups of orbits called shells. Different atoms will have various numbers of electrons in concentric shells about the nucleus. The atoms of known elements on Earth contain a maximum of seven orbital shells. These shells are named K through Q, starting with the innermost shell. Each of these orbital shells contains a number of subshells, currently named s, p, d, f, and g, where the electrons actually reside. The farther a shell is from the atomic nucleus, the more subshells it can contain. An electron’s subshell location determines its energy level. For example, electrons in an f subshell are more energetic than those in an s subshell.
K Shell - The K shell has only an s subshell, which can contain only two electrons. If an atom with only two electrons were to gain a third, the gained electron would have to reside in the next shell’s s subshell.
L Shell - The L shell can hold two subshells: s and p. The p subshell contains a maximum of six electrons. Since the s subshell has a capacity of two electrons, the L shell has a maximum capacity of eight total electrons.
M Shell - The M orbital shell can contain s, p, and d subshells. Its maximum electron capacity is 18.
N Shell - An N shell can accommodate 32 electrons total in its s, p, d, and f subshells.
O Shell - Although, theoretically, the O shell can hold 50 electrons in s, p, d, f, and g subshells, there is no known element on earth that contains enough electrons to completely fill the O orbital shell.
Valence Shells and Valence Electrons
The outer electron shell of an atom is called its valence shell. Copper atoms contain 1 electron in their outermost shell, the N shell; therefore, this shell is copper’s valence shell.
Valence electrons are those that travel farthest from an atom’s nucleus. These electrons determine how an atom reacts chemically. Valence electrons are relatively easy to break loose from their parent atoms compared to electrons within the inner shells due to the distance of the valence shell from the atom’s nucleus. They also may be passed along a material comprised of like atoms, like a copper wire, for example.
Ions
If an electron were to be removed from an atom, the atom would become positively charged due to the fact that it would then contain more protons than electrons. Conversely, if an atom were to gain a greater number of electrons compared to the number of protons, it would then become negatively charged. An atom with an unequal number of protons and electrons is known as an ion.

Main Menu

See Also

Main Menu