Bonding Theories

Chapter 8

Covalent Bonding

8.1 Molecular Compounds
8.2 The Nature of Covalent Bonding
8.3 Binding Theories
8.4 Polar Bonds and Molecules

Vocabulary

8.1 Molecular Compounds

• Covalent bond:atoms that are held together by sharing electrons are joined by

• Molecule: a neutral group of atoms joined together by covalent bonds

• Diatomic molecule: a molecule that contains two atoms

• Molecular compounds: a compound composed of molecules

• Molecular formula: the chemical formula of a molecular compound

8.2 The Nature of Covalent Bonding

• Single Covalent bond: two atoms held together by sharing one pair of electrons

• Structural formula: represents the covalent bonds as dashes and shows the arrangment of covalently bonded atoms

• Unshared pair: A pair of valence electrons that is not shared between atoms

• Double covalent bond: a bond that involves two shared pairs of electrons

• Triple covalent bond: bond formed by sharing three pairs of electrons

• Coordinate covalent bond: covalent bond in which one atom contributes both bonding electrons

• Polyatomic ion: a tightly bound group of atoms that has a positive or negative charge and behaves as a unit

• Bond dissociation energy: energy required to break the bond between two covalently bonded atoms

• Resonance structers: structures that occur when it is possible to draw two or more valid electron dot structures that have the same number of electron pairs for a molecule or ion

8.2 The Nature of Covalent Bonding

• Single Covalent bond: two atoms held together by sharing one pair of electrons

• Structural formula: represents the covalent bonds as dashes and shows the arrangment of covalently bonded atoms

• Unshared pair: A pair of valence electrons that is not shared between atoms

• Double covalent bond: a bond that involves two shared pairs of electrons

• Triple covalent bond: bond formed by sharing three pairs of electrons

• Coordinate covalent bond: covalent bond in which one atom contributes both bonding electrons

• Polyatomic ion: a tightly bound group of atoms that has a positive or negative charge and behaves as a unit

• Bond dissociation energy: energy required to break the bond between two covalently bonded atoms

• Resonance structers: structures that occur when it is possible to draw two or more valid electron dot structures that have the same number of electron pairs for a molecule or ion

8.3 Bonding Theories

• Molecular orbital: When two atoms combine, this model assumes that their atomic orbitals overlap

• Bonding orbital: a molecular orbital that can be occupied by two electrons of a covalent bond

• Sigma bond: two atomic orbitals combine to form a molecular orbital that is symmetrical around the axis connecting two atomic nuclei

• Pi bond: a covalent bond in which the bonding electrons are most likely to be found in sausage-shaped regions above and below the bond axis of the bonded atoms

• Tetrahedral angle: a bond angle of 109.5 that results when a central atom forms four bonds directed toward the center of a regular tetrahedron

• VSEPR theory: the repulsion between electrons pairs causes molecular shapes to adjust so that the calence-electron pairs stays as far apart as possible

• Hybridization: several atomic orbitals miz to form the same total number of equicalent hybrid orbitals

8.4 Polar Bonds and Molecules

• Nonpolar covalent bond: a covalent bond in which the electrons are shared equally by the two atoms

• Polar covalent bond/Polar bond: a covalent bond between atoms in which the electrons are shared unequally

• Polar molecule: a molecule in which one side of the molecule is slightly negative and the opposite side is slightly positive

• Dipole: a molecule that has two poles, or regions, with opposite charges

• Van der wasls forces: the two weakest attractions between molecules

• Dipole interactions: polar molecules are attracted to one another

• Dispersion forces: the weakest of all molecular interactions, are called by the motion of electrons

• Hydrogen bonds: attractive forces in which a hydrogen covlently bonded to a very electronegative atom is also weakly bonded to an unshared electrons pair of another electronegative atom

• Newtork solids: a solid in which all of the atoms are covalently bonded to each other