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Solids & Crystal Structures
the structure of solids
crystalline solids Amorphous solids
Are those whose particles molecules or ions have an ordered arrangement
Are those whose particles are randomly arranged and have no ordered long range structure Like rubber
crystalline solids
Molecular solids Ionic solids Network covalent solids
Metallic solids
Are those whose constituent particules are molecules held together by intermolecular forces like ice, sucrose
Whose particules are ions NaCl
Whose atoms are linked by covalent bonds in three dimension Diamond graphite
In which the structural units are electrons and cations like Ag, Fe
Crystal Structures
Unit cell is the smallest repeating unit of the crystal
Coordination number
is the number of atoms which with a given atom is in contact
Basic unit cells of crystal lattices
Cubic
Tetragonal
Orthorhombic
Monoclinic
Triclinic
Rhombohedral
Hexagonal
cubic Hexagonal
Unit Cells in the Cubic Crystal System
Coordination number 8 12 6 Number of atom per unit cell 2 4 1
Atomic radius in cubic cells
2r = s 4r = s √2 4r = s √3
• Silver metal crystallize in a face centered cubic cell with edge of the unit cell having a length 0.407nm. Calculate the atomic radius of silver
• The ionic radii of Na + and Cl - are 99 and 181 pm respectively what is the length of the unit cell of NaCl (unit cell of NaCl is given in the picture)
Solutions
Homogeneous mixtures are called solutions.
Solvent solute
is the component present in greatest amount or determines the state of solution exist
is a component present in a lesser quantity and it is said to be dissolved in the solvent.
concentrated solution
A solution is one that has a relatively large quantity of dissolved solute
dilute solution A solution has only small quantity of solute
electrolyte nonelectrolyte
Substances whose water solutions conduct electricity are called electrolyte
Solute Solvent Solution example
Gas Gas Gas Air
Gas Liquid Liquid soda (CO2 in H2O)
Liquid Liquid Liquid ethanol in water
Solid Liquid Liquid Saline solution (NaCl in H2O)
Gas Solid Solid H2 in Pd
Solid Solid Solid 14 karat gold (Ag in Au)
Mass of solute
Percent by mass = ------------------------ x 100
Mass of solution
Volume of solute
Percent by volume = ------------------------- x 100
Volume of solution
Mass of solute
Mass / volume percent = --------------------- x 100 (gr/100ml)
Volume of solution
Solution Concentrations
Solution Concentrations
Number of moles of soluteMolarity = ----------------------------------------------- Number of liters of solution
Number of moles of soluteMolality = -------------------------------------------------- Number of kilograms of solvent
Moles of component iMole fraction = --------------------------------------------------------- total moles of all solution components
Parts per million (ppm), Parts Per Billion(ppb) mg solute g solute1 ppm = -------------------- 1 ppb = ----------------------- kg solution kg solution
• question.
A solution has a density of 1.235g/ml and contains 90.0% glycerol C3H8O3 and 10% H2O by mass. Determine
a- the molarity of C3H8O3
b- the molarity of H2O
c- mole fraction of C3H8O3
d- mole percent of H2O
e- the molality of H2O
• question.
A solution has a density of 1.235g/ml and contains 90.0% glycerol C3H8O3 and 10% H2O by mass. Determine
a- the molarity of C3H8O3
b- the molarity of H2O
c- mole fraction of C3H8O3
d- mole percent of H2O
e- the molality of H2O