Chemical Bonds: Ionic, Covalent, and Metallic Bonds

Chemical Bonding

Chemical bonding is the attractive force that holds atoms together in atomic groupings. Atoms that achieve stability by sharing electrons with other atoms are linked by a covalent bond.

Water

Water remains liquid at room temperature, whereas other similar substances are immediately converted into gases.

• The density of water increases to abnormally high temperatures from 0 to 4°C, reaching a maximum value of 1000 kg/m³. Above or below these temperatures, water expands, and its density decreases.
• In its solid state, water floats on liquid water, contrary to what occurs with other substances.
• Water is an excellent heat storage medium. Its resistance to increasing or decreasing its temperature is higher than that of other liquids or solids.
• Water can keep insects floating on its surface, as well as objects such as needles or pins, which are much denser than water.
• Water is the best solvent and the best carrier for substances such as sodium chloride and nitrate.

Electron pairs shared by oxygen and hydrogen are not located symmetrically. They are attracted more strongly by the oxygen nucleus than by the hydrogen nucleus. Therefore, oxygen is left with a partial negative charge, and hydrogen with a positive charge. Water is a polar molecule or a dipole.

Ionic Bond

An ionic bond is based on electron transfer and involves the electrostatic attraction between positive and negative ions.

Properties of Ionic Compounds

• They are crystalline solids at room temperature.
• They have high melting and boiling points.
• They have high hardness and resistance to being scratched.
• They are fragile and brittle.
• They are poor conductors of electricity in a solid state.
• They are good conductors of electricity when they are melted.
• Most are very soluble in water.

Metallic Bond

A metallic bond is formed when the outer electron shells of metal atoms overlap, and electrons are delocalized, not belonging to any particular atom.

Building Materials

• Limestone

Fertilizers

• Nitrogen
• Phosphorus
• Potassium

Detergents

• Ammonia

Uses of Sodium Chloride

• Indigestion tablets
• Soaps and detergents
• Paper and fiberglass
• Street lamps
• Soft water etching