A manipulative activity for exploring effective nuclear charge (Zeff)

High-school and undergraduate college students may often rely on memorization when learning periodic trends, leading to an ineffective understanding of introductory chemistry concepts like atomic radius, ionization energy, and electron affinity. Comprehension of effective nuclear charge (Zeff) is foundational to a complete understanding of periodic trends. Zeff remains an abstract concept for many students, indicating that a manipulative activity for teaching the phenomenon could be a useful way to explain the concept for greater student comprehension. Here we report a hands-on learning activity to target this knowledge gap using magnetic attraction as an analogy for electrostatic attraction within the atom. This approach enables students to explore the phenomenon of effective nuclear charge at a macroscopic level and apply their learning to periodic trends and related concepts. We anticipate that this activity will fill a long-standing hole in the active learning of chemical principles. Importantly, this activity is low-cost and can be assembled using readily accessible materials to allow implementation in most classrooms and virtual learning environments.