Particles in Solution & Dissolving w/o Water 21.3 & 21.4

Electrolytes vs Nonelectrolytes Electrolytes: compounds that produce solutions of ions in water & conduct electricity Nonelectrolytes: substances that form no ions in water and do not conduct electricity What is an ion? An ion is a charged particle that has greater or fewer electrons than protons Ions will be represented by the element with either a (+/-) as a superscript

What’s the difference? Electrolytes Form ions Conduct Electricity Nonelectrolytes Don’t form ions Do NOT conduct electricity

Ionization Ions: charged particles with more or less electrons than protons Ionization: the process in which molecular compounds dissolve in water and form charged particles

Dissociation Dissociation: the process in which positive and negative ions mix with the solvent to form a solution

Effects of Adding Solute Particles By adding solute particles (the part that dissolves) to a solvent (the thing doing the dissolving) two things happen: Freezing point is lowered Solute particles prevent the solute from forming an orderly solid (freezing) Boiling point is raised Solute particles block part of the surface, making it more difficult to vaporize (boil)

Polarity If an object is polar then it has partial positive and partial negative charges at opposite ends of the molecule If an object is nonpolar then it does not have charges on the molecule Remember: Like particles dissolve like particles Polar dissolves polar Nonpolar dissolves nonpolar

When Water doesn’t Work Water is a polar molecule Oxygen has a partial negative charge & both hydrogens have partial positive charges This means that nonpolar solvents cannot dissolve in water or other polar solvents

Why is this useful? Soap is a common item in many households Soaps are substances that have both polar and nonpolar properties Soaps are salts of fatty acids- meaning they have nonpolar tails with polar (water loving) heads Oils are nonpolar and thus the nonpolar tails of soap are attracted to the oils Polar Head Nonpolar Tail Soap Molecule

How Soap Works The nonpolar tails dissolve in the oil and the ionic (polar) end dissolves in water. This means that oil can be removed from skin, clothing, dishes, etc.

Wrap Up What are the differences between electrolytes and nonelectrolytes? What is an ion? What does ionization mean? How do things dissolve? Like dissolves ________ Polar dissolves ____________ How does soap work?