ABSTRACT
As the name suggests, the periodic table shows patterns in properties that repeat at regular intervals. This repetition in properties is what connects elements that appear together in the same group. The periodic trends considered in this chapter are atomic radius (r), ionization energy (E i), electron affinity (E ea), and electronegativity (ꭓ). We can explain the pattern in these properties by using Coulomb's law, which defines the electrostatic force between two charged particles, and the electron configuration of the atom. The trends of size, ionization energy, and electron affinity are correlated. That is hydrogen, a small atom, has a high ionization energy and high electron affinity, while caesium, a large atom, has a low ionization energy and low electron affinity. Electronegativity is a composite property that is connected to atomic size, ionization energy, and electron affinity, and is defined, by Pauling, as the power of an atom to attract electrons to itself. Electronegativity can be measured by various methods with slightly different results, revealing the subtle but relevant fine distinctions in this property.
