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.
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:•.•.•.
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-).
Cation Example:
Sodium Loses an electron: Na• → Na+
Anion Example:
Chlorine Gains an electron: Cl:•.•.•.•.•.•.•. → Cl:•.•.•.•.•.•.•.• (8 dots total) with a -1 charge.
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.
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.
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.
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+).
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.
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.