Physical and Chemical Properties of Matter

Physical Properties and Physical Changes Physical properties describe matter’s ability to change its physical form without altering its chemical structure Examples: state of matter, density (mass per volume), electrical conductivity, color, hardness, shape, magnetic properties, solubility Physical changes don’t produce any different arrangements of atoms before and after the change

State of Matter and Density Change in state of matter does not produce any different types of matter, it merely changes the energy level of the matter. Change in density also involves a change in energy level but no change in the type of matter. Example: water freezing to ice- it’s still H2O but the density and state of matter have changed.

Change of State Terms Melting: Solid to Liquid Sublimation: Solid directly to Gas Freezing: Liquid to Solid Evaporation: Liquid to Gas Condensation: Gas to Liquid Deposition: Gas directly to Solid Ionization: Gas to Plasma Recombination: Plasma to Gas

Electrical Conductivity The ability of matter to conduct an electrical current Electricity flowing through matter does not change the type of matter

Magnetic Properties Most magnetic matter can be magnetized and demagnetized. Changes in magnetism do not change the type of matter.

Solubility Solubility describes the ability of a solvent to dissolve a solute Matter dissolving into other matter does not change the chemical structure of either the solvent or solute

Solubility Solvent: the substance in largest quantity in the mixture; dissolves other substances Solute: a substance which dissolves into a solvent Concentration= mass of solute/volume of solvent

Water: The Universal Solvent! Water is known as the universal solvent because it dissolves a wide variety of solutes Water owes this great solubility to the fact that water molecules are polar meaning the have a positive end and a negative end due to electrical charge

Chemical Properties Chemical Properties describe the ability of substances to change into other substances Examples: combustibility (the ability to catch fire), rusting, chemical reactions, nuclear fusion and fission, biological reactions, change in pH

Chemical Changes Chemical Changes (a.k.a. chemical reactions) are changes in matter which produce one or more new molecules which were not present before the change. All chemical changes are chemical reactions - gas bubbles forming, change of state, change in temperature can all indicate a chemical change has occurred, but the only absolute proof a chemical change has occurred is the formation of a different substance!

Combustibility Combustibility is the ability of matter to ignite (catch on fire) Burning is always a chemical change!

Rusting Very common chemical reaction (always a chemical change)

Chemical Reactions All chemical reactions are chemical changes (the opposite is also true- all chemical changes are chemical reactions) Chemical Reactions are represented by chemical equations- just like a math equation!

Nuclear Fission: heavy elements breakdown into lighter elements Nuclear Fusion: light elements combine into heavier elements

Biological Reactions All biological organisms are basically one big chemical reaction happening from birth to death. Chemical Change examples: All metabolism (building and breaking down of materials in the body), photosynthesis and cell respiration, digestion, cell growth

The pH Scale: measures how acidic or basic a solution is

Acids Acids are between 0 and 7 on the pH scale Acids produce the ion hydronium - H3O+ when dissolved in water Examples: citric acid (found in lemon juice), acetic acid (vinegar), sulfuric acid, hydrochloric acid

Bases Bases are between 7 and 14 on the pH scale Bases produce the ion hydroxide - OH- when dissolved in water Examples: sodium bicarbonate (baking soda), sodium or potassium hydroxide (lye), ammonia

Acids and Bases Acids and bases neutralize each other meaning they cancel each other out and make the solution more neutral Change in pH are chemical changes because forming hydronium makes a chemical bond and forming hydroxide breaks a chemical bond