1.5 Atomic Structure and Electron Configuration

Represent the ground-state electron configuration of an atom of an element or its ions using the Aufbau principle. Atomic Structure and Properties UNIT 1

• The atom is composed of negatively charged electrons and a positively charged nucleus that is made of protons and neutrons.
• Coulomb’s law is used to calculate the force between two charged particles. EQN: Fcoulombic ∝ q1q2 r2
• In atoms and ions, the electrons can be thought of as being in “shells (energy levels)” and “subshells (sublevels),” as described by the ground-state electron configuration. Inner electrons are called core electrons, and outer electrons are called valence electrons. The electron configuration is explained by quantum mechanics, as delineated in the Aufbau principle and exemplified in the periodic table of the elements.
  • Exclusion: The assignment of quantum numbers to electrons in subshells of an atom will not be assessed on the AP Exam.
• The relative energy required to remove an electron from different subshells of an atom or ion or from the same subshell in different atoms or ions (ionization energy) can be estimated through a qualitative application of Coulomb’s law. This energy is related to the distance from the nucleus and the effective (shield) charge of the nucleus.