11/17/08
Post date: Nov 17, 2008 1:56:7 AM
Bell Activity: Give an example of a physical property.
Chemical properties
Describe how a substance changes into a new substance
By combining with other substances or
by breaking apart into new substances
Flammability - the ability to burn
Reactivity - the capacity of a substance to combine with another substance
Iron combines with oxygen to form rust
Hydrogen peroxide decomposes into water and oxygen
Changes of matter - Group presentations
Physical changes
Affects one or more physical properties of a substance without changing the identity of the substance
Melting - change of state, but same substance
Cutting - change of size, but same substance
Crushing - change of shape, but same substance
Dissolving is a physical change
Sugar dissolves in water, but you can still taste it
Water molecules spread out the molecules of the other substance, but don't alter them
Chemical changes
One or more substances are changed into entirely new substances with different properties
Can be detected by a change in taste, smell, color, etc.
Cannot be reversed by physical changes
Breaking down mixtures and compounds
Mixtures can be physically separated
Some compounds can be broken down through chemical changes
Pop quiz - Chapter 2, section 3 material from presentations