PF

Ionic vs. Covalent Compounds

Ionic Compounds vs. Covalent Compounds

  • Ionic Compounds:

    • Electrons are transferred between atoms.

    • Made up of metal and nonmetal elements.

    • Formed from formula units.

    • Have high melting points.

    • Conduct electricity when dissolved in water or molten.

  • Covalent Compounds:

    • Electrons are shared between atoms.

    • Made up solely of nonmetal elements.

    • Formed from molecules.

    • Have low melting points.

    • Generally do not conduct electricity, except for acids.

Quiz Preparation

  • A memory quiz is scheduled for this Friday.

    • Students must have page 10 of the workbook (honors side up).

    • Elements and polyatomic ions must be memorized for the quiz.

    • Students can use Quizlet or note cards for study aids.

    • A score of over 85% is needed to earn credit; scores under 85% will result in a zero.

    • Students have three opportunities to take the quiz before the exam.

    • Knowledge of polyatomic ions is required until after the second final in May.

Understanding Ions

  • Definition of an Ion: An atom that has a charge.

    • Example: Sodium ion is formed when sodium loses an electron.

    • Parent atoms are generally more reactive due to incomplete electron shells.

    • Noble gases are unreactive because they have full outer shells (octet rule).

  • Valence Electrons:

    • Sodium has 1 valence electron; loses this electron to achieve stable electronic configuration like neon.

    • Chlorine has 7 valence electrons; gains 1 electron to reach an octet and forms chloride ion.

  • Safety of Consuming Ions:

    • Sodium is safe as sodium ion (table salt).

    • Chlorine in its atomic form is hazardous as it can form toxic gases.

  • Importance of Ions in Chemistry:

    • Metals generally lose electrons to become cations.

    • Nonmetals generally gain electrons to become anions.

Lewis Dot Structures

  • Lewis Dot Structures:

    • Used to represent valence electrons around an atom.

    • Each electron is represented by a dot, starting with one on each side before pairing.

  • Examples:

    • Nitrogen has 5 valence electrons.

    • Method: Place one on each side and then pair them.

    • Helium has 2 valence electrons.

    • Can be represented as dots in various arrangements.

    • For elements like Sodium (which has 1) and Barium (which has 2), ensure correct representation with pairs where applicable.

Practical Applications of Ions

  • Demonstration of Electronic Transfer:

    • Example: Sodium (Na) loses 1 electron to form Na⁺.

    • Example: Chlorine (Cl) gains 1 electron to form Cl⁻.

    • Visual representation through sketches showing before and after configurations.

Example Problems:

  • Ionic Compound: Sodium Fluoride (NaF)

    • Sodium contributes 1 electron (Na⁺) and Fluorine gains 1 electron (F⁻) to fulfill the octet.

  • Ionic Compound: Magnesium Bromide (MgBr₂)

    • Magnesium has 2 valence electrons and loses both to produce Mg²⁺ while two Bromine atoms (Br) gain 1 electron each to achieve a full octet.

Conclusion

  • It's essential to understand the characteristics, behaviors, and representations of ionic and covalent compounds, the role of ions, and the practical understanding through exercises and applications.

  • Instructions and reminders for class practices and review activities are critical for reinforcing these concepts in preparation for assessments.