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.

robot