recording chem online (mon 02/24)

Ionic Bonding Basics

• Seeking Stability:

  • Sodium (Na) gives up one electron.

  • Chlorine (Cl) gains one electron.

  • Result: Na loses its outer electron and becomes Na+, while Cl gains one electron to complete its octet, becoming Cl-.

  • Both achieve stability resembling noble gas configurations.

Lewis Dot Symbols

• Purpose of Lewis Dot Symbols:

  • Represents valence electrons.

  • Example: Sodium (Na) has one valence electron, represented as Na•.

  • Chlorine (Cl) has seven valence electrons, represented as Cl:•.•.•.•.•.•.•.•.

• Placement of Dots:

  • Arrangement of dots around the symbol can vary, but total must match the number of valence electrons.

• Example of Boron (B):

  • Boron has three valence electrons, represented as B:•.•.•.

Valence Electrons Interactions

• When atoms form compounds, their valence electrons interact to create ionic bonds.

• Nonmetals:

  • The number of unpaired dots equals the number of bonds formed.

• Cations and Anions:

  • Cations are positively charged (e.g., Na+).

  • Anions are negatively charged (e.g., Cl-).

Representation of Ions

• Cation Example:

  • Sodium Loses an electron: Na• → Na+

• Anion Example:

  • Chlorine Gains an electron: Cl:•.•.•.•.•.•.•. → Cl:•.•.•.•.•.•.•.• (8 dots total) with a -1 charge.

Ionic Compounds

• Definition of Ionic Bonding:

  • Electrostatic attraction between oppositely charged ions.

  • Example: Na+ attracts Cl- to form NaCl.

• Neutrality of Ionic Compounds:

  • The overall charge in ionic compounds must be neutral.

• Summary on Charges:

  • Charges of ions add up to balance resulting in a neutral compound.

Lattice Energy

• Definition:

  • Energy required to break an ionic bond.

• Coulomb's Law in Ionic Bonding:

  • Describes the force of attraction between ions based on their charges and distance: ( F \propto \frac{q_1 \times q_2}{d^2} )

• Factors Affecting Lattice Energy:

  • Higher charges result in higher lattice energies.

  • Greater ionic radii (distance) results in lower lattice energies.

Ionic Compound Examples

• Lithium Iodide vs. Magnesium Oxide:

  • Lithium + Fluoride (F-) gives +1 and -1 charges.

  • Magnesium (Mg) has a +2 charge with Oxide (O2-).

  • Compounds formed: MgO requires higher lattice energy due to higher charges compared to LiI.

Naming Ions and Compounds

• Monoatomic Cations:

  • Named by adding the word 'ion' (e.g., Na+ is Sodium Ion).

• Monoatomic Anions:

  • Named by changing element's name to 'ide' (e.g., Cl- is Chloride Ion).

• Transition Metals:

  • Can form multiple charges; names include 'ferrous' (Fe2+) and 'ferric' (Fe3+).

Electronically Neutral Ionic Compounds

• The sum of all charges must equal zero.

• Example Calculation:

  • For Aluminum Oxide (Al2O3), Aluminum is +3 and Oxygen is -2.

  • Combine using charge-to-subscript method to ensure neutrality: Al3+ + 3O2- results in Al2O3.

Conclusion and Review Queries

• Key takeaways: ionic bonds involve the transfer of electrons resulting in charged ions that attract due to opposite charges.

• The understanding of Lewis dot symbols assists in visualizing valence electrons and predicting bond formation.