Classifications of Matter

Matter Flowchart MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous MixtureCompoundElement MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes

 Elements are a pure substance  Cannot be separated into anything else  Made of a single atom  Compounds are made of multiple atoms combined together  Can be separated into individual atoms ▪ Burning, electrolysis, reactions

Colloids and suspensions are heterogeneous mixtures

LecturePLUS Timberlake5 Have medium size particles Cannot be filtered Separated with semipermeable membranes Scatter light (Tyndall effect)

 In a solution, dispersed particles are molecule-sized (roughly 0.1 nm).  In a colloid the dispersed particles are 1 – 1000 nm.

Light scattered by the (larger) colloidal particles makes the beam visible.

LecturePLUS Timberlake8 Fog Whipped cream Milk Cheese Blood plasma Pearls

LecturePLUS Timberlake9 Have very large particles Settle out Can be filtered Must stir to stay suspended Example: Dirt in water

Solutions Solutions are homogeneous mixtures

 Homogeneous mixture where particles are individual atoms, ions, or compounds.  All in same phase

A solute is the dissolved substance in a solution. A solvent is the dissolving medium in a solution. Solvent Salt in salt water Sugar in soda drinks Carbon dioxide in soda drinks Water in salt waterWater in soda

Fats Fats Benzene Benzene Steroids Steroids Hexane Hexane Waxes Waxes Toluene Toluene Polar and ionic solutes dissolve best in polar solvents Nonpolar solutes dissolve best in nonpolar solvents Inorganic Salts Water Water Sugars Sugars Small alcohols Small alcohols Acetic acid Acetic acid

 The solubility of MOST solids increases with temperature.  The rate at which solids dissolve increases with increasing surface area of the solid.  The solubility of gases decreases with increases in temperature.  The solubility of gases increases with the pressure above the solution.

Solids tend to dissolve best when: o Heated o Stirred o Ground into small particles Gases tend to dissolve best when: o The solution is cold o Pressure is high

 Form aqueous solutions  Many biological fluids are solutions or have solution components  One of best solvents for dissolving ionic substances  Poor solvent for non-polar covalent substances.

H H O ---- ++++ OHH ++++ ---- O H H ++++ ---- O H H ---- O H H ++++ ---- “H-bonding” binds water molecules tightly.

 Water is one of best solvents for ionic material (electrolytes)  Water’s polar molecular structure interacts strongly with charged ions  Water---Ion attractions replace ion---ion and water---water attractions with little net energy change

Water Na + Cl - Crystal’s +/- attractions cause lattice energy, which must be overcome to break up crystal.

Water Na + Cl -

Water Na + Cl - Several more H 2 O molecules may associate “Void” weakens crystal and makes it more likely to break up in vicinity.

Water Na + Cl -

Water Na + Cl -

Water Na + Cl - Positive Note: Positive ions associate with negative ends of waters, and negative ions associate with positive ends of waters. +/- forces release energy

Separating a Mixture Manual sorting Filtration Melting Point Boiling Point

Separating a Mixture Boiling Evaporation Magnetic Properties

Separating a Mixture Distillation

Separating a Mixture Chromatography