Topic 11: Metallic Bonding and Crystallography
No description yet. This curated deck is ready for daily study.
Card preview (24)
In close packing of sphere, the 2nd layer will form … to the 1st
identically
There is 2 types of close packing depending on where the 3rd layers sits: … and …
hexagonal cubic
In hexagonal close packing, the 3rd layer sits … so has a … layer arrangement with … (number of spheres). It occupies … of the total volume.
directly over the 1st A B A 7 spheres in A , 3 in B, 7 in A 74%
Unit cell
Smallest parallel-sided volume element of a crystal structure (atom arrangement) Represents much larger lattice
In cubic close packing/Face centred packing, the 3rd layer sits … and the 4th layer sits … so has a … layer arrangement with … (number of spheres). It occupies … of the total volume.
over the holes the the 1st layer directly over the 1st A B C A 1 sphere in A, 6 in B, 6 in C and 1 in A 74%
Describe a HCP unit cell (number + location of spheres, dimensions, coordination number)
4 at top corners (A), 1 in middle (B), 4 at bottom corners (A) Side lengths: a = b < c Angles: α = β = 90°, γ = 120° 12 coordination number
Describe a FCC/CCP unit cell (number + location of spheres, dimensions, coordination number)
5 at top (4 corners, 1 face) 4 in middle (faces) 5 at bottom (4 corners, 1 face) Diagonally 1,6,6,1 Side lengths: a = b = c Angles: α = β = γ = 90° 12 coordination number
Describe a BCC unit cell (number + location of spheres, dimensions, coordination number)
4 at top corners (A), 1 in middle (B), 4 at bottom corners (A) Side lengths: a = b = c Angles: α = β = γ = 90° 8 coordination number
Describe a Primitive unit cell (number + location of spheres, dimensions, coordination number)
one atom in each corner of cube Side lengths: a = b = c Angles: α = β = γ = 90° 6 coordination number
CCP and FCC are ….
the same
In Body-Centred cubic packing, the spheres are arranged in … based on … not … . The 2nd layer sits … so … and the 3rd layer sits … .It occupies … of the total volume.
layers square rows triangular directly over a gap in the 1st pushes the spheres slightly apart directly over the 1st 68%
A BCC unit cell has … spheres in its layers. Its coordination number is …
4 at top corners 1 in middle 4 at top corners 8
2 main solid structures
crystalline amorphous
Arrangement of atoms in crystalline solids
orderly array called a lattice regular internal arrangement of atoms
Arrangement of atoms in amorphous solids
atoms lie in a random jumble similar structure to liquids
Atomic crystalline solids are held together by … . Examples are … . They have low …
diversion forces noble gases melting and boiling points
Molecular crystalline solids are held together by … . Lattice points are occupied by …
inter-molecular individual molecules
Ionic crystalline solids are held together by … . Electrons are … to form … and held together by …
transfer between atoms anions and cations electrostatic forces
Metallic crystalline solids have a … surrounded by an array of … held together by … . Interaction are maximised when … are …
sea of electrons cations electrostatic forces cations close packed
Network covalent crystalline solids are held together by … which … . These are …
strong covalent bonds extend throughout the solid forming a network hard
Name the crystalline solids
Atomic Molecular Ionic Metallic Network covalent
How does metals being malleable and ductile relate to its structure
delocalised electrons lead to non-directional bonding without breaking bonds
How does metals being electrical and thermal conductors relate to its structure
Delocalised electrons are mobile
Define alloy
blend of metals or a metal and other element(s) that is prepared by mixing the molten components and then cooling Elements have been mixed together at an atomic level