Download Science Notes on Physical and Chemical Properties

Science Notes on Physical and Chemical Properties
PHYSICAL PROPERTY
Definition: A feature or characteristic of matter which can be observed without changing the identity of the
matter
Examples:
Color
Density
Conductivity –thermal and electrical
Smell
Malleability
Melting Point
Taste
Ductility
Boiling Point
Texture
Solubility
Magnetism
Malleability - how well something can be flattened or stretched without breaking
Metals tend to be malleable – example is gold and copper
Wood and glass are NOT malleable
Ductility -
the ability to be stretched into a wire
Solubility -
how well one material dissolves in another material. (Insoluble means cannot dissolve)
measured by the amount of solute that can dissolve in 1000mL of water
Things that affect solubility:
1. Temperature – as temperature increases so does the rate of dissolving
2. Stirring – speeds up dissolving
3. Surface Area - smaller pieces/particles – dissolve faster that large pieces of material
4. Amount of solute – greater amounts of solute require longer times to dissolve
Solute -
the chemical being dissolved: the material you add to a solvent
Solvent -
a chemical that dissolves things: the material in which you add a solute
Examples:
Chocolate mile – the syrup is the solute and the mile is the solvent
Tea – the tea leaves are the solute and the hot water is the solvent
Magnetism - how well something sticks to a magnet
Conductivity There are 2 kinds
1. Thermal Conductivity – how well heat travels through a substance
2. Electrical Conductivity – how well electricity travels through a substance
Melting Point the point at which a solid becomes a liquid
Boiling Point the point at which a liquid becomes a gas
Characteristic A feature of matter that is specific to the substance and does NOT change with the amount
Property
of substance…example…density, melting point and boiling point are characteristic properties
CHEMICAL PROPERTIES
Definition: How one thing reacts with another
Examples:
1. Flammability – how well something reacts with oxygen to produce heat/flame
2. Reactions with acid – how well something reacts with an acid. Main reaction with and acid results
in bubbling. When an acid reacts with another substance, usually hydrogen gas (which is highly
explosive) is released
3. Other Reactions – include heat being released, bubbling, strong odor, smoke, flame, change of
color, etc.
4. Non-Reactivity – when something fails to react…example…platinum dropped in acid has no
reaction…nothing happens. Even when held into a flame, platinum has no reaction
** Main Point to Remember about Chemical Reactions…
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They always produce a new substance – totally different that the substance you started with
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Most chemical reactions cannot be reversed
Characteristic Property – Can be Physical or Chemical
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Something unique to a substance – doesn’t matter how much or how little the sample of matter is
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Chemical characteristic property (of sodium) = sodium ignites when in contact with water
PHYSICAL CHANGE
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The appearance may change, but you still have the same substance as before – can be reversed and no
energy is produced
Example – Tear a piece of paper into 10-15 pieces. The shape and size have changed, but its still
paper
Example – Change of state = physical change…add energy to ice and you get a liquid…add more
energy and you get a gas…all physical changes as it is still water
Example – Dissolving things is a physical change…salt in water will temporarily mix then separate
out if left standing…can be separated back into water and salt
CHEMICAL CHANGE
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A change that occurs when materials react or are broken into different materials
In a chemical change the physical appearance changes and you have a different substance than what
you started out with
BOTH physical and chemical properties may change
Energy may be produced or absorbed
Usually chemical changes cannot be reversed unless you make another chemical change