Final answer:
Elements in the periodic table are arranged in order of increasing atomic number, and this arrangement depicts repeating patterns in chemical and physical properties. Groups contain elements with similar properties, and atomic size trends can be observed across periods and down groups.
Step-by-step explanation:
Elements in the periodic table are arranged in order of increasing atomic number, with no gaps. This is a fundamental principle known as the periodic law, which states that when elements are arranged this way, there is a periodic repetition of their chemical and physical properties.
The periodic table serves as a chart where elements are ordered into rows and columns. These rows are called periods, and within each period, the atomic number increases from left to right. The columns are known as groups, and elements in each group share similar chemical properties. For example, Group 1 contains the alkali metals, while Group 17 contains the halogens, and Group 18 contains the noble gases. The design of the periodic table reflects periodic trends such as changes in atomic size.