Periodic trends

When comparing the properties of the chemical elements, recurring ('periodic') trends are apparent. This led to the creation of the periodic table as a useful way to display the elements and rationalize their behavior. When laid out in tabular form, many trends in properties can be observed to increase or decrease as one progresses along a row or column.

These period trends can be explained by theories of atomic structure. The elements are laid out in order of increasing atomic number, which represents increasing positive charge in the atomic nucleus. Negative electrons are arranged in orbitals around the nucleus; recurring properties are due to recurring configurations of these electrons.

These periodic trends are distributed among 3 different properties, namely physical properties, chemical properties and on the basis of chemical reactivity. In chemical properties, it is classified on the basis of two; i.e. periodicity of valence or oxidation states, anomalous properties of second period elements. In this article the periodic trends with respect to their physical properties are briefly discussed.