Octet Rule

Bonding is crucial in forming different molecules and life-sustaining compounds.

• Example compounds include water (H2O) and carbon dioxide (CO2).

• Living things are made of biochemical compounds categorized into four groups:

  • Proteins

  • Carbohydrates

  • Lipids

  • Nucleic acids

• Molecular compounds consist of nonmetals held together by covalent bonds.

• The kit serves as a guide for writing chemical formulas and understanding valence electrons and Lewis structures.

• Developed by chemist Gilbert Lewis, the octet rule explains how elements form ions and molecules.

• It states main group elements bond to achieve eight electrons in their valence shell, mimicking noble gas configurations.

• Key points of the octet rule:

  • Atoms with fewer than eight electrons will react to form stable compounds.

  • Atoms can satisfy the octet rule by:

    1. Sharing valence electrons (covalent bonding).

    2. Transferring valence electrons (ionic bonding).

• Exceptions:

  • Helium has only two valence electrons, affecting hydrogen.

  • Lithium tends to lose one electron to achieve stability.

Types of Bonding

Ionic Bond

• Also known as an electrovalent bond.

• Forms through the permanent transfer of valence electrons between atoms.

• The atom losing electrons becomes a cation (positively charged), while the atom gaining electrons becomes an anion (negatively charged).

• Example: Formation of sodium chloride (NaCl) involves electron transfer from sodium to chlorine.

• Ionic compounds demonstrate alternating positive and negative charges, resulting in a neutral overall charge.

Covalent Bond

• Also known as a molecular bond; involves sharing electron pairs between atoms to achieve a lower energy state.

• The shared electrons form bonding pairs, leading to a balance of attractive and repulsive forces.

• Types of Covalent Bonds:

  • Single Bond: 1 pair of electrons shared (2 electrons total).

  • Double Bond: 2 pairs of electrons shared (4 electrons total).

  • Triple Bond: 3 pairs shared (6 electrons total).

Properties of Covalent Bonds

• Single Bonds:

  • Most stable, depicted with a single line.

  • Weaker than double or triple bonds, less reactive.

• Double Bonds:

  • Stronger than single bonds, but less stable.

  • Depicted with two lines.

• Triple Bonds:

  • Least stable, most reactive.

  • Depicted with three lines.

Naming Compounds

Binary Molecular Compounds

• Formed from the reaction of two nonmetals.

• Named similar to binary ionic compounds:

  1. First element retains its name.

  2. Second element is treated as an anion, with the suffix -ide.

  3. Numerical prefixes indicate the number of atoms:

     • 1 = mono-, 2 = di-, 3 = tri-, 4 = tetra-, etc.

• Example Names/Formulas:

  • CO = Carbon monoxide

  • Cl2O7 = Dichloride heptoxide

  • N2O5 = Dinitrogen pentoxide