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