Elements in the same group of the periodic table share common properties due to having the same number of valence electrons, which are the electrons in the outermost shell of an atom. These valence electrons are responsible for the chemical behavior of elements. Some common properties of elements in the same group include:1. Similar chemical reactivity: Elements in the same group tend to react similarly with other elements because they have the same number of valence electrons available for bonding.2. Gradual change in physical properties: As you move down a group, the atomic size increases due to the addition of electron shells. This can lead to a gradual change in physical properties such as melting and boiling points, atomic radius, and ionization energy.3. Similar electron configurations: Elements in the same group have the same general electron configuration, which is responsible for their similar chemical properties.4. Trend in electronegativity: Electronegativity is the measure of an atom's ability to attract electrons in a chemical bond. In general, electronegativity decreases as you move down a group, making elements at the top of the group more electronegative than those at the bottom.5. Oxidation states: Elements in the same group tend to exhibit similar oxidation states in their compounds due to their similar valence electron configurations.6. Formation of similar compounds: Elements in the same group can form similar compounds with other elements because of their similar chemical reactivity and oxidation states.These common properties allow chemists to predict the behavior of elements and their compounds, making the periodic table a valuable tool in the study of chemistry.