CFE Physical Science Honors Practice Test 2025 – Comprehensive Exam Prep

Elements in the same group of the periodic table share similar chemical properties and have the same number of valence electrons. This similarity arises because the valence electrons determine how atoms interact with one another during chemical reactions. For instance, elements in Group 1, such as lithium, sodium, and potassium, all have one valence electron, which makes them highly reactive and leads them to form similar types of chemical bonds, typically forming cations with a charge of +1.

Additionally, the similar number of valence electrons across a group means that the elements will typically behave in a similar fashion in terms of bonding and reactivity. For example, Group 17 elements, the halogens, all have seven valence electrons and are known for readily gaining one electron to achieve a stable electronic configuration, which is characteristic of their chemical behavior. This pattern is consistent across all groups in the periodic table, helping to predict the chemical interactions of different elements based on their group placement.