Final answer:
The modern day periodic table is organized according to the atomic number of elements, with elements placed in periods and groups that reflect their properties and similarities.
Step-by-step explanation:
The modern day periodic table is organized by the atomic number of elements. This definitive characteristic is crucial because it reflects the number of protons in the nucleus of an atom, which determines the element's identity. In Mendeleev's original table, elements were organized by increasing atomic mass, but this system was later refined to focus on atomic numbers once it was understood that the properties of elements are periodic functions of their atomic numbers.
The table is structured into horizontal rows called periods and vertical columns known as groups, with each group containing elements that share similar chemical properties.The table helps to neatly categorize the elements into seven periods and 18 groups, each presented by boxes that include the element's atomic number, symbol, average atomic mass, and sometimes the name.
The periodic law, which is a modern concept of the table, states that the properties of elements are periodic functions of their atomic numbers. Essentially, elements are arranged by increasing atomic numbers in such a manner that the ones with similar properties fall into the same group or column, which greatly helps scientists and students alike in understanding chemical behaviors and relationships.