Atomic Charge and Electron Configuration

Ever wonder why some atoms attract or repel each other? It all comes down to atomic charge. An atom's charge is determined by the balance between its protons and electrons. When the numbers are equal, the atom is neutral. If an atom gains electrons, it becomes negatively charged (an anion). If it loses electrons, it becomes positively charged (a cation).

Electrons exist in specific energy levels called shells around the nucleus. Think of these shells like floors in an apartment building—the ground floor (closest to the nucleus) has the lowest energy. Each shell contains subshells (labeled s, p, d, f, g, h) which hold different numbers of electrons. The space within each subshell where electrons are most likely found is called an orbital, and each orbital holds a maximum of two electrons.

You can calculate how many electrons fit in each shell using the formula 2n² (where n is the shell number). For example, the first shell can hold 2 electrons, while the second shell holds 8 electrons. For subshells, the formula 2$2l+1$ tells you the capacity (where l is the subshell number).

Quick Tip: Remember that electrons always fill the lowest energy orbitals first (the Aufbau principle). However, some higher-numbered shells (like 4s) can fill before lower ones (like 3d) because they actually have lower energy!

When writing electron configurations, you'll list each subshell in order of increasing energy, showing how electrons are distributed throughout the atom. This organization explains nearly everything about how an element behaves chemically.