1. Matter: Changes and Properties

2. During a physical change, a substance changes some physical property,
but it is still the same material with the same chemical composition. Ex. Water can change states to be solid, liquid, or gas
gas
H2O
solid
liquid

3. Any change involving a rearrangement of atoms.
Chemical Change:
Any change involving a rearrangement of atoms.

4. Recognizing Chemical Changes
Energy is absorbed or released (temperature changes hotter or colder, light released)
Color changes
Gas production (bubbling, fizzing, or odor change; smoke)
Formation of a precipitate - a solid that separates from solution (won’t dissolve)
Irreversibility - not easily reversed

5. The formation of a compound
Chemical Change
The formation of a compound
Physical Change
The formation of a mixture

6. Law of Conservation of Matter During a chemical change, matter is neither created nor destroyed.
Conservation of Matter: Matter can neither be created nor destroyed.
Atoms rearrange in chemical reactions – the macroscopic (what we see) view of things may appear as though ‘new’ matter has been created. However, at the microscopic level we would see only that compounds and molecules have been broken apart and rearranged into new compounds and molecules (from the same atoms we started with).
This is a demonstration using potassium iodide mixed with lead nitrate to yield a precipitate of lead (II) iodide and soluble potassium nitrate.
A small test tube filled with lead nitrate is resting inside the Erlenmeyer flask. When inverted, the chemical reaction occurs.
No new material is added to the flask - it is a closed system. During the chemical reaction, atoms are rearranged.
The product has different properties (i.e. it changes from colorless to yellow) than the reactants.
Lead (II) iodide is very toxic. Dispose of waste in a responsible manner.
Lead (II) iodide is also the pigment added to road stripe paint.
Reactants yield Products

7. This is an image showing molecules of a compound
This is an image showing molecules of a compound. Which of the pictures below represent a chemical change and which represent a physical change?
Chemical Chemical Physical

8. Decide whether each is a chemical or physical change.
Boil Burn Condense Corrode Crumple Ferment Melt Rust Crush
Freeze Oxidize Tarnish Explode Grind Rot Vaporize

9. Decide whether each is a chemical or physical change.
Boil- physical Burn- chemical Condense- physical Corrode-chemical Crumple- physical Ferment-chemical Melt- physical Rust- chemical Crush- physical
Freeze- physical Oxidize- chemical Tarnish- chemical Explode- chemical Grind- physical Rot- chemical Vaporize- physical

10. Physical and Chemical Properties
Examples of Physical Properties
Boiling point Color Slipperiness Electrical conductivity
Melting point Taste Odor Dissolves in water
Shininess (luster) Softness Ductility (wire) Viscosity (resistance to flow)
Volatility (evaporates) Hardness Malleability (sheet) Density (mass / volume ratio)
Examples of Chemical Properties
Burns in air Reacts with certain acids Decomposes when heated
Explodes Reacts with certain metals Reacts with certain nonmetals
Tarnishes Reacts with water Is toxic

11. INTENSIVE property
- Does not change depending on the size of the sample
color, melting point, boiling point, odor, density
Ex. A cup of water will start to boil at the same
temperature as a whole pot of water
EXTENSIVE property
- Does change depending on the size of the sample
mass, volume, heat content (calories)
Ex. A mini Snickers bar has less calories than a full size Snickers bar