Chemical Bonding Types and Molecular Properties

Ionic Bonds

In ionic bonds, the electrons are transferred completely from one atom to another.

Properties of Ionic Compounds

• They are solid at room temperature.
• In the solid state, they do not conduct electric current, but they do when they are molten or dissolved.
• They have high melting points.
• They are hard, but fragile.
• They offer much resistance to dilation.
• They are very soluble in water and other polar solvents.

Examples

NaCl, H₂O, Li₂O

Covalent Bonds

The bonding between atoms that are equal or differ little in their electronegative character cannot be explained by the ionic bond. The covalent bond is the union of atoms that share one or more pairs of electrons.

Single Covalent Bonds

When the atoms involved in the link require only one electron to complete their noble gas configuration, they share a single pair of electrons to form a single covalent bond.

Multiple Covalent Bonds

Very often, some atoms saturate their binding capacity with more than one shared pair of electrons. This situation leads to the formation of a covalent double bond, and if there are three, a triple bond.

Apolar and Polar Covalent Bonds

Apolar: When the molecule consists of equal atoms that do not differ in their electronegativity, which are called nonpolar molecules. Examples: Cl₂, H₂

Polar: When the atoms that bond have different electronegativities, the molecule establishes a zone where the electron density concentrates in a greater way, creating a positive and a negative pole.

Coordinate Covalent Bonds

This link takes place between different atoms and is characterized by shared electrons coming from only one of the atoms that are bound. The atom that brings the electron pair is called the donor, and the acceptor receives it. The coordinate covalent bond is represented by an arrow from the atom that provides two electrons and is directed towards the atom that receives them.

Properties of Covalent Substances

• They have low melting and boiling points.
• When they are in a solid state, they are relatively soft and poor conductors of heat and electricity.
• They are fairly stable and have low reactivity.

Metallic Bonds

The metal atoms are characterized by having few electrons in their last level, also called the valence level; therefore, the formation of molecules is not possible in the traditional sense.

Properties of Solid Metals

• They can be deformed without breaking the crystal structure.
• A plane of atoms can slip without losing its structure.
• They are good conductors of electricity.
• They have excellent thermal conductivity.

Intermolecular Forces

• Dipole-dipole interactions
• Interactions of hydrogen bonds
• Interactions through London forces
• Interactions by ion-dipole attractions