Chapter 5 PowerPoint Slides

Chapter 5 Ionic and Covalent Compounds

Section 5.1: Compounds

• Definition: A compound is composed of two or more elements combined in a specific ratio, held together by chemical bonds.

• Examples: Water (H2O) and Sodium Chloride (NaCl).

Section 5.2: Lewis Dot Symbols

• Lewis dot symbols represent the valence electrons of an atom.

• Each dot corresponds to a valence electron.

• Valence electrons play a crucial role during compound formation.

Section 5.3: Ionic Compounds and Bonding

• Ionic bonding occurs through electrostatic attraction between oppositely charged ions (cations and anions).

• Example: Sodium Chloride (NaCl) consists of Na+ and Cl− ions, combining to form a neutral compound.

• Definition: A lattice is a three-dimensional arrangement of oppositely charged ions.

• Lattice energy: Energy required to separate a mole of ionic solid into gaseous ions.

• Lattice stability correlates with the magnitude of the ion charges and their distance apart.

Lattice Energies of Selected Ionic Compounds

• NaCl:- Lattice Energy: 788 kJ/mol- Melting Point: 801 °C- Example compounded with MgO (3890 kJ/mol) showing greater lattice energy indicates higher stability.

Section 5.4: Naming Ions and Ionic Compounds

• Monatomic Cations: Named by adding 'ion' to the element name. (e.g., K+ is potassium ion.)

• Monatomic Anions: Named by changing the ending of the element name to -ide. (e.g., Cl− is chloride.)

• Transition metals may form multiple cations—indicate charge with Roman numerals. (e.g., Fe2+ is ferrous, Fe3+ is ferric.)

Section 5.5: Covalent Bonding and Molecules

• Covalent bonding involves sharing electrons to achieve a noble gas configuration.

• Lewis theory illustrates this with the example of hydrogen molecules (H2): H· + ·H → H:H.

• A molecule is formed when two or more atoms are chemically bonded.

Section 5.6: Molecular Formulas

• Molecular formulas show the exact number of atoms of each element in a molecule.

• Example of allotropic forms: Oxygen (O2) vs. Ozone (O3).

Section 5.7: Covalent Bonding in Ionic Species

• Polyatomic ions are groups of atoms that collectively carry a charge (e.g., sulfate as SO4^2−).

• Charges must balance to yield neutral compounds.

Section 5.8: Molecular and Formula Masses

• Molecular mass is calculated by summing the atomic masses of the constituent elements, measured in atomic mass units (amu).

• For ionic compounds, use empirical formulas to assess formula mass.

Worked Example: Molecular mass calculation for water

• H2O = 2 × 1.008 amu (H) + 16.00 amu (O) = 18.02 amu.

Section 5.9: Percent Composition of Compounds

• The percent by mass of each element in a compound is defined as its percent composition.

• Example for H2O2: %H and %O are calculated based on molecular mass.

Section 5.10: Molar Mass

• Molar mass is the mass in grams of one mole of a substance, equal to the atomic mass in amu parsed into grams.

• Example: Molar mass of H2O is 18.02 g/mol.

Interconverting Mass, Moles, and Numbers of Particles

• Strategies: Convert between grams, moles, and particles using molar mass and Avogadro's number.

Worked Example: Interconvert moles and grams of CO2

• (a) 10.00 g CO2 → 0.2272 mol CO2 using molar mass.

• (b) Find mass of 0.905 mol of NaCl = 52.9 g.

Section 5.11: Determination of Empirical Formula

• The empirical formula represents the simplest ratio of atoms in a compound.

• Example: Percent composition can help retrieve the empirical formula from molecular data.

Section 5.12: Naming Molecular Compounds

• Binary molecular compounds follow systematic naming conventions. Use Greek prefixes for quantities.

• Example: HCl is hydrogen chloride, while N2O5 is dinitrogen pentoxide.

Section 5.13: Naming Acids and Organic Compounds

• Acids derived from –ide ions are named by modifying the -ide to -ic or -ous.

• Organic compounds: Hydrocarbons containing only C and H, with alkanes as the simplest form.

Summary of Key Points

• Compounds can be ionic or covalent, with their behaviors defined by bonding theories such as Lewis theory.

• Names and formulas of compounds are based on the properties of the constituent elements and their arrangements.