Chemistry Chapter 5: Compounds

Chapter 5: Compounds

• Compounds: Substances formed when two or more different elements chemically combine.

• Ionic Compounds: Composed of metallic and non-metallic elements. Held together by electrostatic attraction between oppositely charged ions (cations and anions). Typically have high melting and boiling points, are often soluble in water, and conduct electricity when dissolved or molten.

• Covalent Compounds: Composed primarily of non-metallic elements. Held together by sharing of electrons. Generally have lower melting and boiling points than ionic compounds, and are generally not soluble in water. Do not conduct electricity in any state.

• Diatomic Molecules: Seven elements naturally exist bonded to an identical atom: Hydrogen (H₂), Nitrogen (N₂), Oxygen (O₂), Fluorine (F₂), Chlorine (Cl₂), Bromine (Br₂), Iodine (I₂).

• Naming Compounds: Students need to be able to name ionic and covalent compounds from their formulas, and vice versa.

• Hydrates: Hydrates are ionic compounds that contain specific proportions of water molecules within their crystal structure. Students need to be able to calculate the % of water in a hydrate and determine the number of water molecules in the hydrate from the mass of the original and dehydrated compound.

• Electronegativity (EN): A measure of an atom's ability to attract electrons in a chemical bond.

• ΔEN: The difference in electronegativity values between two atoms in a bond. Used to predict the type of bond (covalent, polar covalent, or ionic) based on the range (0-0.5 covalent, 0.5-1.7 polar covalent, >1.7 ionic)

• Lewis Structures: Visual representations of the valence electron arrangement in molecules, including bonding and nonbonding (lone) pairs of electrons.

Chapter 6: Metallic and Intermolecular Bonds

• Metallic Bonds: Bonds that form between metal atoms. Characterized by a "sea" of delocalized electrons that are shared collectively by all atoms. These bonds result in properties like high electrical and thermal conductivity, malleability, and ductility.

• Alloys: Mixtures of two or more metallic elements or a metal and a nonmetal. Their properties often differ from those of the constituent elements.

• Hydrogen Bonds: Special type of dipole-dipole attraction between a hydrogen atom bonded to a highly electronegative element (O, N, F) and another highly electronegative atom.

• VSEPR Theory: Valence Shell Electron Pair Repulsion Theory; it predicts the shapes of molecules based on the repulsion between electron domains (bonding pairs and lone pairs) around the central atom.

• Molecular Geometry: The arrangement of atoms in a molecule. Students must be able to predict shapes (limited to molecules with 2, 3, or 4 electron domains) with VSEPR.

• Polarity: The polarity of a molecule is determined by both electronegativity differences and the molecular shape.

Prior Chapter Concepts

• Stoichiometry: Conversions between mass, moles, and number of particles (atoms, molecules).
• Isotopes: Atomic notations illustrating element with varying numbers of neutrons.
• Phase Diagrams: Diagrams used to illustrate the different states of matter (solid, liquid, gas) and their transitions at various temperatures and pressures.
• Gas Laws: Relationship between pressure, volume, temperature, and amount of gas.
• Electron Configurations: Arrangement of electrons in an atom's orbitals and electron shells.
• Periodic Table (7 Heavenly Virtues): This concept is unclear, please clarify.