How bonding and structure are related

• The three states of matter are solid, liquid, and gas
• Melting and freezing take place at the melting point
• Boiling and condensing take place at the boiling point
• Particle theory can help explain melting, boiling, freezing, and condensing
• The amount of energy needed to change state depends on the strength of forces between particles
• The nature of particles involved depends on the type of bonding and structure of the substance
• The stronger the forces between particles, the higher the melting and boiling points
• Limitations of the simple model include no forces, all particles represented as spheres, and solid spheres
• State symbols in chemical equations: solid (s), liquid (l), gas (g), and (aq) for aqueous solutions
• Properties of ionic compounds:
• Ionic compounds have regular structures (giant ionic lattices) with strong electrostatic forces of attraction in all directions between oppositely charged ions
• They have high melting and boiling points due to the energy required to break strong bonds
• When melted or dissolved in water, ionic compounds conduct electricity because ions are free to move
• Ionic compounds cannot conduct electricity when solid because ions are fixed in place
• Properties of small molecules:
• Substances with small molecules are usually gases or liquids with low boiling and melting points
• They have weak intermolecular forces between molecules, broken in boiling or melting, not the covalent bonds
• Intermolecular forces increase with the size of molecules, larger molecules have higher melting and boiling points
• Substances with small molecules do not conduct electricity because they do not have an overall electric charge
• Polymers:
• Have very large molecules
• Atoms in polymer molecules are linked by strong covalent bonds
• Intermolecular forces between polymer molecules are relatively strong, making them solids at room temperature
• Giant Covalent Structures:
• Substances with giant covalent structures are solids with very high melting points
• All atoms in these structures are linked by strong covalent bonds
• Examples include diamond, graphite, and silicon dioxide (silica)
• Properties of metals and alloys:
• Metals have giant structures of atoms with strong metallic bonding
• Most metals have high melting and boiling points
• Layers of atoms in metals can slide over each other, allowing metals to be bent and shaped
• Alloys are made from 2 or more different types of metals
• Different sized atoms in alloys distort the layers in the structure, making them harder than pure metals
• Metals as conductors:
• Good conductors of electricity due to delocalised electrons carrying electrical charge through the metal
• Good conductors of thermal energy because energy is transferred by delocalised electrons