Mid.%20Lesson2

Ionic and Covalent Bonds

Classification of Elements

• Metals

  • Good conductors of heat and electricity

  • Malleable (can be hammered into sheets)

  • Ductile (can be drawn into wires)

• Nonmetals

  • Poor conductors of heat and electricity

  • Not malleable or ductile

  • Can be gases, liquids, or solids at room temperature

• Metalloids

  • Intermediate properties of metals and nonmetals

  • Can conduct electricity under certain conditions (semiconductors)

Ionic and Covalent Compounds

• Ionic Compounds (IC)

  • Formed from the combination of metals and nonmetals

  • Example: Sodium chloride (NaCl)

• Covalent Compounds (CC)

  • Formed from the combination of nonmetals

  • Example: Water (H2O)

Electronegativity

• Definition

  • Measures the tendency of an atom to attract electrons when chemically combined with another atom

  • Noble gases do not form bonds; hence, they have no electronegativity value.

• Electronegativity Differences Determine Bond Types

  • Ionic Bond: ∆EN > 1.7

  • Polar Covalent Bond: 0.4 ≤ ∆EN ≤ 1.7

  • Nonpolar Covalent Bond: ∆EN < 0.4

Examples of Electronegativity Calculations

1. Calcium (Ca) and Chlorine (Cl)

   • EN(Ca) = 1.0, EN(Cl) = 3.0

   • ∆EN = |1.0 - 3.0| = 2.0 (Ionic Bond)

2. Chlorine (Cl) and Chlorine (Cl)

   • EN(Cl) = 3.0, EN(Cl) = 3.0

   • ∆EN = |3.0 - 3.0| = 0 (Nonpolar Covalent Bond)

3. Hydrogen (H) and Chlorine (Cl)

   • EN(H) = 2.1, EN(Cl) = 3.0

   • ∆EN = |2.1 - 3.0| = 0.9 (Polar Covalent Bond)

Polarity of Molecules

• A polyatomic molecule with nonpolar bonds cannot be polar, while a molecule with polar bonds may be polar or nonpolar based on its shape

• Factors to Determine Polarity

  • Bond polarity

  • Molecular shape

• If the bonds are polar and the molecular shape is asymmetric, the molecule is polar. If the bonds are nonpolar or the shape is symmetrical, the molecule is nonpolar.

Examples of Molecular Polarity

1. Nitrogen Bromide (NBr3)

   • EN(N) = 3.0, EN(Br) = 2.8

   • ∆EN = 0.2 (Nonpolar Covalent, Nonpolar Molecule)

2. Carbon Dioxide (CO2)

   • EN(C) = 2.5, EN(O) = 3.0

   • ∆EN = 0.5 (Polar Bonds, Nonpolar Molecule due to linear geometry)

Molecular Shapes

• Linear

• Trigonal Planar

• Bent or Angular

• Tetrahedral

• Trigonal Pyramidal

• Trigonal Bipyramidal

• Octahedral

References

• Solid and practical insights at: https://www.studocu.com/ph/document/university-of-the-east-philippines/the-physical-sciences/grade-11-physical-science-q3-slm1/26361557

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