Periodic Law
Definition and meaning of Periodic Law in chemistry.
The periodic law states that the physical and chemical properties of the elements are periodic functions of their atomic numbers. This means that when elements are arranged in order of increasing atomic number, elements with similar properties appear at regular intervals.
In more detail
The modern periodic law is the fundamental basis for the organization of the periodic table of elements. It arises from the fact that chemical properties are determined by the electron configuration of an atom, specifically the number of valence electrons located in the outermost shell. Because the pattern of filling electron shells repeats as atomic number increases, the properties of the elements also exhibit repeating trends, such as atomic radius, ionization energy, and electronegativity. This principle transformed chemistry from a collection of isolated facts into a predictive and systematized scientific discipline.
Key facts
| Field | General Chemistry |
|---|---|
| Ordering property | Atomic number |
| Underlying cause | Electron configuration |
According to the periodic law, lithium, sodium, and potassium all appear in the same group because they each have one valence electron, resulting in similar high reactivity with water.
Frequently asked questions
Who first proposed the periodic law?
Dmitri Mendeleev first proposed the periodic law based on atomic weight, which was later corrected by Henry Moseley to be based on atomic number.