Properties of Metals in Chemistry

General Properties

• Metals are generally good conductors of heat and electricity. This is due to the loosely held valence electrons in their structure.
• They are typically strong and durable, exhibiting high tensile strength. This is because the metallic bonding allows for the atoms to slide past each other without breaking the bond.
• Metals are malleable; they can be hammered or rolled into thin sheets. This is because of the delocalized electrons that allow for the atoms to rearrange.
• Metals are ductile; they can be drawn into wires. This is a result of the same delocalized electron structure that facilitates malleability.
• Metals have a lustrous (shiny) appearance due to the way their free electrons scatter and absorb light.
• Most metals are solids at room temperature, an exception being mercury (Hg), which is a liquid.

Specific Properties

• Density: Metals generally have high densities, although there are exceptions. Density is a measure of mass per unit volume.
• Melting Point: Most metals have high melting points, indicating the strength of the metallic bonds. This requires a significant amount of energy to overcome the attraction between the positive ions and delocalized electrons.
• Hardness: Metals vary in hardness. Some, like iron, are relatively hard, while others, such as sodium, are quite soft. Hardness relates to the strength of the metallic bonding and the ability of the atoms to resist deformation.
• Conductivity (electrical and thermal): The electron sea model explains the excellent electrical and thermal conduction of metals. Electrons can move freely throughout the structure, readily carrying heat or electrical energy.
• Reactivity: Metals vary considerably in their reactivity. Some, like potassium, react violently with water, while others, like gold, are very unreactive. Reactivity is related to the ease with which a metal loses electrons in chemical reactions.

Metallic Bonding

• Metallic bonding is characterized by a "sea" of delocalized valence electrons that are shared among a lattice of positive metal ions. This shared pool of electrons holds the ions together.
• The attraction between these delocalized electrons and the positively charged metal ions accounts for the properties of metals.
• The strength of the metallic bond depends on the number of valence electrons available and the size of the metal ions.

Alloys

• Alloys are mixtures of two or more elements, at least one of which is a metal. The properties of alloys are often different from those of the constituent metals.
• Alloys are created to improve specific desired properties, such as strength, hardness, or corrosion resistance.
• Examples include steel (iron and carbon), brass (copper and zinc), and bronze (copper and tin).
• The addition of other elements can alter the properties of a metal. For example, adding carbon to iron creates steel, which is significantly stronger than pure iron.

Differences between Metals, Nonmetals, and Metalloids

• Metals are generally good conductors, malleable, and ductile, and typically have high melting and boiling points.
• Nonmetals are generally poor conductors, brittle, and are typically gases or solids at room temperature.
• Metalloids have properties that are intermediate between those of metals and nonmetals. They can be semi-conductors, meaning they conduct electricity under certain conditions.