Chemistry Chapter 5 Study Guide

Periodic Concepts

• Periodicity refers to repeating patterns in properties of elements.
• The Periodic Law states properties of elements are periodic functions of their atomic numbers.
• The Periodic Table organizes elements according to their properties and atomic numbers.

Modern Periodic Table

• Elements are arranged by atomic number, grouping similar properties together.
• Incorporates newly discovered elements including Noble Gases, Lanthanides, and Actinides since Mendeleev's time.

Lanthanides and Actinides

• Lanthanides (Atomic #s 58-71): Shiny, reactive metals filling F orbitals, similar to alkaline earth metals.
• Actinides (Atomic #s 90-103): Mostly synthetic, radioactive metals, with only 90-92 occurring naturally.

Structure of the Periodic Table

• Periods run horizontally and their length is determined by the number of electrons in sub-levels.
• The s, p, d, and f blocks correspond to electron configurations, indicative of group placement:
  • s block: max 2 electrons
  • p block: max 6 electrons
  • d block: max 10 electrons
  • f block: max 14 electrons.

Element Groups

• Alkali Metals (Group 1): Highly reactive, soft silvery metals, stored under oil, rarely found in nature.
• Alkaline Earth Metals (Group 2): Harder and denser than Alkali Metals, less reactive, cannot be found freely in nature.
• Transition Elements (Groups 3-12): Shiny, conductive, ductile, and malleable, with less reactivity compared to Groups 1 and 2, some found as native elements.
• Main Group Elements (Groups 13-18): Occupy s and p blocks, varied properties; include metals, nonmetals, and metalloids.
• Halogens (Group 17): Most reactive non-metals, capable of forming salts with metals.
• Noble Gases (Group 18): Stable, full outer electron shells, rarely undergo chemical reactions.

Ionization and Ionic Character

• Ion: Charged atom or group of atoms.
• Ionization: Process resulting in ion formation.
• Cation: Positively charged ion.
• Anion: Negatively charged ion.

Atomic and Ionic Properties

• Atomic Radii: Half the distance between nuclei of bonded atoms.
• Ionic Radii: Half the diameter of an ion; important in crystal lattice calculations.
• Ionization Energy: Energy needed to remove an electron from a neutral atom.
• Electron Affinity: Energy change when an electron is gained by a neutral atom.
• Electronegativity: Measure of an atom’s ability to attract electrons in a compound.

Pioneers in Chemistry

• Stanislao Cannizzaro: Developed methods for accurate atomic mass measurements, aiding standardization.
• Dmitri Mendeleev: Created the first Periodic Table, predicting properties of undiscovered elements based on atomic mass.
• Henry Moseley: Established the modern Periodic Law, arranging elements by increasing atomic number instead of mass.

Valence Electrons

• Group configurations indicate the number of valence electrons: Groups 1 and 2 equal their group number; Groups 13-18 have valence equal to group number minus 10.

Prepare for your chemistry exam with this study guide focused on Chapter 5. Explore key terms such as periodic law and the periodic table, along with their definitions. Enhance your understanding of how elements are organized and their properties.