Chemical Bonding and States of Matter

This page covers fundamental concepts in chemistry, focusing on the formation of ions, different types of chemical bonds, and the states of matter. It provides a comprehensive overview of how atoms interact to form various substances and how these substances behave under different conditions.

Formation of Ions

Ions are formed when atoms gain or lose electrons to achieve a stable electron configuration.

Definition: Ions are charged particles that can be single atoms or groups of atoms.

The process of ion formation involves the transfer of electrons, with atoms either losing or gaining electrons to attain a full outer shell, which makes them very stable.

Highlight: The number of electrons gained or lost determines the charge of the ion.

Ionic Bonding

Ionic bonding occurs when a metal and a non-metal react together.

Example: In the formation of sodium chloride (NaCl), sodium (a metal) loses an electron to chlorine (a non-metal).

The metal loses electrons to form a positively charged ion, while the non-metal gains electrons to form a negatively charged ion. This transfer of electrons creates strong electrostatic forces of attraction between the oppositely charged ions.

Vocabulary: Dot and cross diagrams are used to show the arrangement of electrons in atoms or ions.

Ionic compounds have several characteristic properties:

• They form regular lattice structures with closely packed ions.
• They have high melting and boiling points due to the strong bonds between ions.
• They cannot conduct electricity when solid, but can conduct when melted as the ions are free to move.

Covalent Bonding

Covalent bonding occurs between non-metal atoms and involves the sharing of electron pairs.

Definition: A single covalent bond shares one electron from each atom involved in the bond.

Covalent bonds can be represented using dot and cross diagrams, where shared electrons are shown in the overlap between two atoms.

Simple molecular substances are made up of molecules containing a few atoms joined by covalent bonds. These substances have weak forces of attraction between molecules.

Polymers and Giant Covalent Structures

Polymers are long chains of repeating units with strong intermolecular forces, making them typically solid at room temperature.

Giant covalent structures, also known as macromolecules, have all atoms bonded together by strong covalent bonds.

Highlight: Giant covalent structures have very high melting and boiling points and do not conduct electricity.

Examples of giant covalent structures include diamond and graphite.

Metallic Bonding

Metallic bonding is characterized by delocalized electrons in the outer shell of metal atoms.

Vocabulary: Delocalized electrons are free to move around within the metal structure.

Properties of metals due to metallic bonding include:

• High melting and boiling points
• Good conductors of electricity and heat
• Malleability (ability to bend and change shape)

Alloys, which are mixtures of two or more metals, are generally harder than pure metals.

States of Matter

Matter exists in three main states: solid, liquid, and gas. The state of a substance depends on:

• The material itself
• Temperature
• Pressure

Definition:

• Solids: Strong forces between particles, particles don't move, keep their shape
• Liquids: Weak forces, particles free to move past each other, don't keep shape
• Gases: Very weak forces, particles free to move and far apart

State symbols are used to indicate the state of a substance:

• (s) for solid
• (l) for liquid
• (g) for gas
• (aq) for aqueous (dissolved in water)

The transitions between states include melting (solid to liquid), freezing (liquid to solid), boiling (liquid to gas), and condensing (gas to liquid).