ACSI 2022 HL Notes Atomic Structure (Teacher)

IBDP Chemistry HL/ Atomic Structure Page 1 Anglo − Chinese School (Independent) Year 5 (2022) IBDP Chemistry HL (IBDP syllabus Topic 2) 2.1 The nuclear atom - Essential Idea: the mass of an atom is concentrated in its minute positively charged nucleus. 2.2 Electron configuration - Essential Idea: the electron configuration of an atom can be deduced from its atomic number. (IBDP syllabus Topic 12) 12. 1 Electrons in atoms - Essential Idea: the quantized nature of energy transitions is related to the energy states of electrons in atoms and molecules TOPIC 2 ATOMIC STRUCTURE TEACHER COPY – WITH SUGGESTED SOLUTIONS

IBDP Chemistry HL/Atomic Structure Page 2 2.1 The nuclear atom Essential idea: The mass of an atom is concentrated in its minute, positively charged nucleus.  Nature of Science: • Evidence and improvements in instrumentation—alpha particles were used in the development of the nuclear model of the atom that was first proposed by Rutherford. (1.8) • Paradigm shifts—the subatomic particle theory of matter represents a paradigm shift in science that occurred in the late 1800s. (2.3) Understandings: • Atoms contain a positively charged dense nucleus composed of protons and neutrons (nucleons). • Negatively charged electrons occupy the space outside the nucleus. • The mass spectrometer is used to determine the relative atomic mass of an element from its isotopic composition. Applications and skills: • Use of the nuclear symbol notation XΑ Ζ to deduce the number of protons, neutrons and electrons in atoms and ions. • Calculations involving non-integer relative atomic masses and abundance of isotopes from given data, including mass spectra. 2.2 Electronic configuration Essential idea: The electronic configuration of an atom can be deduced from its atomic number.  Nature of Science: • Developments in scientific research follow improvements in apparatus —the use of electricity and magnetism in Thomson’s cathode rays.(1.8) • Theories being superseded—quantum mechanics is among the most current models of the atom. (1.9) • Use theories to explain natural phenomena—line spectra explained by the Bohr model of the atom. (2.2) Understandings: • Emission spectra are produced when photons are emitted from atoms as excited electrons return to a lower energy level. • The line emission spectrum of hydrogen provides evidence for the existence of electrons in discrete energy levels, which converge at higher energies. • The main energy level or shell is given an integer number, n, and can hold a maximum number of electrons, 2n 2. • A more detailed model of the atom describes the division of the main energy level into s, p, d and f sub-levels of successively higher energies. • Sub-levels contain