A bond where 2 or more atoms share a vacant electron to complete the outershell. It is a strong primary bond
when one electron donates one of its electrons to the other atom to complete its outer shell. the difference in charge attracts the atoms together. it is a strong primary bond
a bond between two or more metal ions whereby the atoms are in a 'sea' of delocalised electrons. a strong primary bond
secondary bond so considerably weaker, arise from dipoles between 2+ atoms or molecules
special type of hydrogen bond whereby hydrogen is one of the constitutes.
The energy required to seperate 2 atoms by an infinite seperation distance.
periodic arrangement of atoms over long distance calle long range order
also called amorphous. short range order only and they are complex structures with rapid cooling
three dimesional array of points coinciding with atom positions
the smallest repiting entities in a structure.
atoms are thought as solid spheres with well defined parameters
a=b=c. all angles = 90 degrees. volume = a^3
a=b/=c. all angles = 90 volume= a^2c
a/=b/=c angles all=90 volume = abc
a=b/=c angles 2=90 and the angle between ab =120
volume = 0.866a^2c
a=b=c all angles are equal but none are 90. volume =
a^3 sqrt(1-3cos^2(α)+ 2cos^3(α)
a/=b/=c angles two equal 90. one angle β /= 90. volume =
a/=b/=c angles all angles different and none =90. volume=
abc sqrt(1-cos^2(α) - cos^2(β)- cos^2(γ) +
2cos(α) cos(β) cos(γ) )
perfectly periodic. all unit cells interlock at the same orientation
collection of many small grains. during solidification many crystals form at various locations. grow from the surronding liquid. graains impinge on one another all at different orientations. may be some mismatch and areas between the grains is called grain boundary.
the directionality of properties
number of atoms touching a particular atom or the number of nearest neighbours for an atom
sum of volume of atoms in a unit cell divided by the unit cell
consists of 8 atoms in the corners of the cell. nothing else
8 quaters in the edges and then one other atom in the middle (interior)
8 quaters in the edges and then one half atom per face
when a material has more than one structure
polymorphism found in a solid structure