The modern periodic table is organized by
alphabetical order of chemical symbols
Increasing number of neutrons
Increasing atomic mass
Increasing atomic number
The correct answer and explanation is:
The correct answer is Increasing atomic number.
The modern periodic table is organized by the atomic number, which is the number of protons in an atom’s nucleus. This order reflects the fundamental property of elements, as the atomic number determines an element’s identity and its position in the table. As you move from left to right across a period (a row of the periodic table), the atomic number increases by one for each successive element.
This arrangement has significant advantages over organizing elements by atomic mass, which was the method used in the earlier versions of the periodic table. The problem with using atomic mass is that it can lead to anomalies in the placement of elements. For example, iodine has a higher atomic mass than tellurium, but iodine is placed before tellurium in the modern periodic table because it has a lower atomic number.
Organizing the table by atomic number also leads to the periodic law, which states that elements with similar properties recur at regular intervals when arranged in this way. Elements in the same column (or group) of the table share similar chemical properties because they have the same number of electrons in their outermost shell, which governs their chemical behavior. For example, elements in Group 1, like lithium, sodium, and potassium, all have one electron in their outer shell, which makes them highly reactive and similar in behavior.
This structure helps predict the properties of elements, even those that have not yet been discovered. It forms the basis for understanding chemical reactions and bonding, making it one of the most important tools in chemistry.