Chemical Bonding and Molecular Structure

What holds Ionic Bonds together

Coulombic attractions between opposite charges

Formation of Ionic Bonds

Involve the transfer (lose/gain) of electron(s) from one atom to another to attain an octet configuration.

Octet Rule

Elements react in a way that results in valence shell containing eight electrons. (watch for exceptions!)

Ionic Crystal Lattice

Cations and anions are surrounded on all adjacent sides by opposite charge, creating a large aggregate structure

Properties of Ionic Compounds

strong bonds, hard and brittle, high melting and boiling points, are electrolytes

Electrical Conductivity of Ionic Compounds

Conduct electricity in molten and aqueous but not in solid state.

Solubility of Ionic Compounds

Soluble in water

Metallic Bond

Metallic bonding is the force of attraction between the positive metal ions and a mobile sea of electrons.

Properties of Metallic Bonds

High luster (shiny), malleable, ductile, conducts heat and electricity

Nonpolar Covalent Bond

The covalent bond is formed when two electrons are shared equally between two atoms.

Bond Length vs Strength

The distance apart where attractive and repulsive forces balance between the nuclei of two non-metallic atoms.

Lewis Electron-Dot Symbols

A representation of the valence electrons in a molecule using dots around the chemical symbols.

Valence Electrons

Electrons in the outer shell of an atom that are involved in forming bonds.

Exceptions to the Octet Rule

Conditions where molecules do not follow the octet rule, such as expanded, incomplete, or odd electron configurations.

Single Bond

A bond formed by one electron pair being shared between two atoms.

Double Bond

A bond formed by two electron pairs being shared between two atoms.

Triple Bond

A bond formed by three electron pairs being shared between two atoms.

Free Radicals

Species that contain lone (unpaired) electrons.

Resonance Structure

Multiple Lewis structures that combine to provide an average structure, mix of single and multiple bonds

Electronegativity

Atom's attraction for electron pairs in bonds.

VSEPR Theory

Predicts molecular shapes based on electron pair repulsion.

Trigonal Planar

Shape with three bonded pairs, no lone pairs around central atom.

Tetrahedral

Shape with four bonded pairs, no lone pairs around central atom.

Trigonal Bipyramidal

Shape with five bonded pairs, no lone pairs around central atom.

Octahedral

Shape with six bonded pairs, no lone pairs around central atom.

Molecular Shape

Arrangement of atoms around a central atom.

Bond Angle

Angle between two adjacent bonds in a molecule.

Bonding Pair

Electrons shared between two atoms in a bond.

Lone Pair

Non-bonding electrons localized on an atom.

Lone Pair Effect on Structure

Lone pairs have extra repulsion which distort bond angles.

Square Planar

Geometry with 4 bonding pairs and 2 lone pairs.

Bond Angles

Angles between bonds in a molecule.

Bent - shape

Geometry with 2 bonding pairs and 1 or 2 lone pairs.

Polar Molecule

Molecule with uneven charge distribution.

Non-Polar Molecule

Molecule with balanced charge distribution.

Molecular Dipole Moment (μ)

Measure of polarity in a molecule.

Bond Polarity

Distribution of electrons in 1 bond between two atoms

Dipole Moment

Net charge on a molecule due to unbalance of electrons

Symmetrical Molecules

Molecules with balanced charge distribution.

Hybridization

Explanation why all bonds within molecule are equal energy (mixing atomic orbitals)

sp Hybridization

2 Electron Regions around Central Atom (One s and one p orbital hybridized)

sp2 Hybridization

3 Electron Regions around Central Atom (One s and two p orbitals hybridized.)

sp3 Hybridization

4 Electron Regions around Central Atom (One s and three p orbitals hybridized)

sp3d Hybridization

5 Electron Regions around Central Atom (One s, three p, and one d orbital hybridized.)

sp3d2 Hybridization

6 Electron Regions around Central Atom (One s, three p, and two d orbitals hybridized)

Metal + Nonmetal

Elements in Ionic Bond

2 Different Nonmetals

Elements in Polar Covalent Bond

Diatomic Elements (2 of same Nonmetal)

Elements in Nonpolar Covalent Bond

H, O, N, Cl, Br, I, F

Diatomic elements (too reactive to be found as single elements)

Dipoles

Partial charges

Properties of Nonpolar covalent compounds

Nonelectrolytes, do not dissolve in water

Properties of Polar covalent compounds

Dissolve partially in water, partial electrolytes

Electrolytes

Can conduct electric current when dissolved in water

Nonmetals prefer to _____ electrons.

Gain

Metals prefer to _____ electrons.

Lose

Why do atoms form chemical bonds?

To fill outer shell (become more stable)

Definition of chemical bond

Force of attraction holding atoms together in a molecule.

Strongest type of bond

Triple bonds b/c they are the shortest

Weakest type of bond

Single bonds b/c they are the longest

H, Be, B, etc

Exceptions to octet rule

What types of atoms can form expanded octets?

Atoms with a d-subshell available (3rd energy level or higher)