2.4 Structure of Metals and Alloys

• Alloys are mixtures of metals or a metal with non-metal elements to modify properties.


  True
• Match the bonding type with its properties:

  Metallic ↔️ High conductivity

  Covalent ↔️ Low conductivity

  Ionic ↔️ High melting point
• What are the key differences between metallic, covalent, and ionic bonding in terms of electron behavior?

  Sea, sharing, transfer
• In metallic bonding, electrons move freely in a sea, enabling high electrical and thermal conductivity.
• In metallic bonding, metal atoms lose their valence electrons to form positively charged cations
• The ability of metals to be hammered into sheets is called malleability
• Arrange the three main crystal structures of metals from lowest to highest density:

  1️⃣ Body-Centered Cubic (BCC)

  2️⃣ Face-Centered Cubic (FCC)

  3️⃣ Hexagonal Close-Packed (HCP)
• Substitutional alloys involve atoms of similar size
• What allows metals to have high electrical and thermal conductivity?

  Delocalized electrons
• What does the metallic bonding theory explain?

  How metal atoms bind
• What property of metals is enhanced by the mobility of delocalized electrons?

  Electrical conductivity
• What type of electron sharing or transfer occurs in ionic bonding?

  Electron transfer
• What is the atom arrangement in the hexagonal close-packed (HCP) structure?

  Hexagonal arrangement
• What are alloys designed to enhance in base metals?

  Properties
• Metals consist of positively charged cations surrounded by a sea of delocalized electrons.
• The lattice structure of metals features a regular arrangement of cations surrounded by delocalized electrons.
• Steps involved in metallic bonding according to metallic bonding theory:

  1️⃣ Metal atoms form positively charged cations

  2️⃣ Valence electrons become delocalized

  3️⃣ Delocalized electrons hold cations together

  4️⃣ Electrical and thermal conductivity results

  5️⃣ Malleability and ductility are enabled
• Which bonding type involves non-metal atoms sharing electrons?

  Covalent
• What is the metallic bonding theory primarily used to explain?

  Binding in metal atoms
• What property of delocalized electrons allows metals to conduct electricity and heat efficiently?

  Mobility
• Match the bonding type with its electron behavior:

  Metallic ↔️ Electrons freely move in a sea

  Covalent ↔️ Electrons shared between atoms

  Ionic ↔️ Electrons transferred between ions
• What do differences in atomic arrangement in metal crystal structures affect?

  Physical properties
• Match the alloy type with an example:

  Substitutional ↔️ Brass (copper and zinc)

  Interstitial ↔️ Steel (iron and carbon)
• The lattice structure of alloys can be either crystalline or amorphous
• Delocalized electrons in metallic bonding belong to a single metal atom.

  False
• Covalent bonding results in high electrical conductivity.

  False
• The face-centered cubic (FCC) structure has high malleability and ductility.


  True
• Interstitial alloys increase the hardness of metals.

  True
• What are metals characterized by in terms of their structure?

  Unique crystal lattice
• Why are metals good electrical conductors?

  Delocalized electrons
• What happens to valence electrons in metallic bonding?

  Delocalized in a sea
• The mobility of delocalized electrons in metallic bonding allows for efficient heat transfer.


  True
• Malleability and ductility in metals are due to the uniform distribution of cations and delocalized electrons.


  True
• In metallic bonding, electrons are delocalized and move freely throughout the lattice


  True
• What is a key difference between metallic bonding and ionic bonding?

  Delocalized electrons
• The Body-Centered Cubic (BCC) structure has low density and high strength.

  True
• Interstitial alloys increase hardness but reduce ductility.


  True
• Alloys can be stronger than pure metals due to their modified lattice structure.


  True
• Metal atoms lose their valence electrons to form positively charged cations
• The uniformity of positive cations and delocalized electrons in metals allows for malleability