The elements in the modern periodic table are primarily arranged by atomic number, which is the number of protons found in the nucleus of an atom. This arrangement leads to a periodic pattern in the properties of the elements.
Each row of the periodic table is called a period, and as you move from left to right across a period, the atomic number increases. Elements in the same group (columns) have similar chemical properties and the same number of electrons in their outermost shell. This is why elements in the same group often exhibit similar reactions with other substances.
The layout of the periodic table also reflects the electron configuration of the elements. For example, the transition metals are found in the center of the table, while the alkaline metals and halogens are situated on the left and right sides, respectively. Overall, the modern periodic table not only organizes elements by atomic number but also systematically groups them by shared characteristics, allowing scientists and students alike to predict the behavior of elements based on their position.