Glossary
Alloys
A mixture of two or more elements, at least one of which is a metal, typically formed by mixing them in their liquid states and then cooling.
Example:
Bronze, an alloy of copper and tin, was crucial in ancient civilizations for making tools and weapons due to its increased strength.
Covalent-Network Solid
A solid in which atoms are held together in a continuous, extended network by strong covalent bonds throughout the entire structure.
Example:
Diamond is a prime example of a covalent-network solid, explaining its extreme hardness and very high melting point.
Delocalized Valence Electrons
Valence electrons in metals that are not associated with a single atom or a covalent bond but are free to move throughout the entire metallic structure.
Example:
The incredible electrical conductivity of silver comes from its delocalized valence electrons, which act like tiny, mobile charge carriers.
Ductility
The ability of a substance, typically a metal, to be drawn out into a thin wire without losing toughness.
Example:
Copper's excellent ductility makes it ideal for manufacturing electrical wires.
Good Conductors of Electricity
The ability of a substance to allow electric current to flow easily through it. In metals, this property arises from the mobility of their delocalized electrons.
Example:
Aluminum foil is a good conductor of electricity, which is why it's used in some electrical components.
High Melting and Boiling Points
The temperatures at which a substance transitions from solid to liquid (melting) and liquid to gas (boiling), respectively. Metals typically exhibit high values due to strong metallic bonds.
Example:
It takes an immense amount of energy to melt iron, demonstrating its high melting point due to strong metallic bonds.
Interstitial Alloys
Alloys formed when smaller atoms fit into the spaces (interstices) between the larger atoms of the host metal lattice.
Example:
Steel is a classic interstitial alloy where small carbon atoms occupy the gaps within the iron crystal structure, making it much stronger.
Ionic Solid
A solid composed of positive and negative ions arranged in a crystal lattice, held together by strong electrostatic attractions.
Example:
Table salt, NaCl, is an ionic solid that is hard and brittle, and only conducts electricity when melted or dissolved.
Malleability
The ability of a substance, typically a metal, to be hammered or pressed into thin sheets without breaking.
Example:
Gold is highly malleable, allowing jewelers to shape it into intricate designs without it cracking.
Metallic Bonding
The chemical bonding found in metals, characterized by a 'sea' of delocalized valence electrons shared among a lattice of positively charged metal ions.
Example:
The strong attraction in a piece of copper metal is due to metallic bonding, allowing it to be drawn into wires.
Metallic Solid
A solid composed of metal atoms held together by metallic bonds, characterized by a 'sea' of delocalized electrons.
Example:
A block of pure iron is a metallic solid, exhibiting properties like malleability and electrical conductivity.
Molecular Solid
A solid composed of discrete molecules held together by relatively weak intermolecular forces, such as London Dispersion Forces, dipole-dipole interactions, or hydrogen bonds.
Example:
Solid iodine, Iā, is a molecular solid that sublimes easily at room temperature due to weak forces between its molecules.
Shiny Appearance
The characteristic luster of metals, resulting from the interaction of light with their mobile delocalized electrons, which absorb and re-emit photons.
Example:
The dazzling shiny appearance of a polished gold ring is a direct result of how light interacts with its free-moving electrons.
Substitutional Alloys
Alloys formed when atoms of one element replace atoms of similar size in the crystal lattice of another element.
Example:
Brass, an alloy of copper and zinc, is a substitutional alloy because zinc atoms, similar in size to copper, replace some copper atoms in the lattice.