11. Metallic Properties and Bonding

Metallic Properties & Bonding (4.1)

Learning Intentions

• Understand and explain the properties of metals including their behavior in various conditions. Success Criteria:

• List the main properties of metals, providing examples for clarity.

• Explain the metallic bonding model, detailing how it contributes to the properties observed in metals.

• List and explain the properties of transition metals with specific characteristics that differentiate them from other metals.

• Use the metallic bonding model to explain major properties of metals, including real-world applications.

Recap of Key Ideas

• Changes in core charge across and down the Periodic Table, affecting properties such as reactivity.

• Changes in electronegativity across and down the Periodic Table, influencing the behavior of metals in compounds.

• Changes in ionization energy across and down the Periodic Table, impacting how easily metals lose electrons.

• Changes in metal reactivity across and down the Periodic Table, which is crucial for understanding their role in reactions.

Key Properties of Metals

• Conductivity: Good conductors of electricity due to the presence of free-moving delocalized electrons within their structure.

• Malleability: Can be hammered or rolled into shape without breaking, making them useful for a variety of applications such as coinage and architecture.

• Ductility: Can be drawn into wire, which allows for electrical wiring and various fabrication processes.

• Lustrous: Reflective surface resulting from the ability of metals to reflect light; this quality is used in jewelry and electronics.

• Melting/Boiling Points: Range widely but generally high, showcasing the strength of metallic bonds; many are solid at room temperature.

• Density: Generally high density due to the closely packed arrangement of atoms which contributes to their strength.

• Hardness: Often hard with high tensile strength, essential for construction materials and tools.

• Ionization & Electronegativity: Low values make metals more likely to lose electrons and form cations in chemical reactions.

Definitions

• Hardness: Measure of atom packing in a substance; harder materials can withstand higher stress and resist deformation.

• Boiling Point: Temperature at which a substance transitions from a liquid to a gas; significant for understanding the states of matter in different elements.

• Melting Point: Temperature at which a substance transitions from a solid to a liquid; often indicates the strength of the bonds holding the atoms together.

• Malleable: Able to be shaped without breaking, allowing for versatility in manufacturing and construction.

• Ductility: Ability to be drawn into wire, crucial for electrical and communication infrastructure.

Metal Cations

• Metals lose one, two, or three outer shell electrons to form cations; this is fundamental for their reactivity and interactions.

• Example: Sodium (Na) loses one valence electron to become Na+; this process illustrates how metals behave in chemical reactions.

• Charge determined by group number: Eg. Na is in Group 1, thus forms a 1+ cation, showcasing the pattern in metal reactivity based on group position.

Metallic Bonding Model

• Definition: Electrostatic forces between positive metal ions and a 'sea' of delocalized valence electrons combine to form a strong metallic lattice which is essential for metal properties.

Properties Explained by the Metallic Bonding Model

• Hardness & High Melting/Boiling Points: The strong attractions between cations and electrons form a hard metallic lattice that requires significant heat to break apart for boiling/melting.

• Electrical Conductivity: Delocalized electrons can move freely within circuits while fixed cations contribute to stability in the structure.

• Malleability & Ductility: The ability of metal layers to shift under force without breaking occurs because the binding by delocalized electrons allows for movement yet maintains integrity.

Limitations of the Metallic Bonding Model

• Cannot explain the range of melting points and densities among different metals, indicating that other factors are at play.

• Differences in electrical conductivity that some metals exhibit are due to factors beyond just the metallic bonding model.

• Magnetic properties of certain metals (e.g., cobalt, iron) which are not accounted for by typical metallic bonding theories.

Review Tasks

• Complete notes from today's lesson.

• Answer Review Questions 1-8 from Exercise 4.1 to reinforce learning.

• Complete Edrolo Quiz and assess understanding of the concepts discussed.