October 19, 2009 Update your planner. Hand in Combinations of Atoms. Open your book to page 44. Set up your Cornell Notes. Today’s Theme: How can we classify.

October 19, 2009• Update your planner.

• Hand in Combinations of Atoms.

• Open your book to page 44.

• Set up your Cornell Notes.

• Today’s Theme: How can we classify matter?

PROPERTIES OF MATTER

Describing Matter

Physical Properties

• A property of matter that can be observed or measured without changing the identity of the matter.

Physical Properties

• Physical properties identify matter.

• Examples include but are not limited to:• Density• States of Matter (Solid, Liquid, Gas, Plasma)• Solubility• Freezing point• Boiling point• Melting point• Color• Smell• Thermal Conductivity• Attraction or repulsion to magnets• Malleability• Ductility• Opacity• Viscosity

Identifying Substances2.1

Physical Properties

• Density is a measure of how much mass is contained in a given unit volume .

• A measure of how tightly that ‘stuff’ is packed together

• A ratio of mass to volume

• Density equals mass divided by volume.• Density = mass ÷ volume or

• Malleability - The ability to be pounded into thin sheets.• Example: Aluminum can be rolled or pounded into

sheets to make foil.

• Ductility - The ability to be drawn or pulled into a wire• Example: Copper in wiring – soldering wires or joints

Physical Property

Physical Property

• Thermal Conductivity - The ability to transfer thermal energy from one area to another.

• Examples:• Plastic foam is a poor conductor, so a hot

drink won’t burn your hand.• The inside of the toaster (hot coils) are good

at transferring heat.

Physical Property

• Solubility - The ability to dissolve in another substance.

• Example:• Sugar or salt dissolve easily in water but

sand dissolves slowly

• Three ways to increase solubility• Heat or make warmer• Grind or smash• Stir or mix

5 States of Matter

Bose-EinsteinCondensate Solid Liquid Gas Plasma

Physical Property

• State of Matter - The physical form in which a substance exists:

• Bose Einstein Condensate - super-unexcited and super-cold atoms.

• Solid – matter has a definite shape and volume• Liquid – matter takes the shape of its container and

has a definite volume• Gas – matter changes in both shape and volume• Plasma – positively charged atoms (ions) and free

electrons.

Bose-Einstein Condensate

• This state of matter was the only one created while you were alive.

• In 1995, two scientists, Cornell and Weiman, finally created this new state of matter.

• Two other scientists, Satyendra Bose and Albert Einstein, had predicted it in the 1920. They didn't have the equipment and facilities to make it happen in the 20s. Now we do.

• If plasmas are super hot and super excited atoms, the atoms in a Bose-Einstein condensate (BEC) are total opposites

States of Matter

What are the atoms doing in each state?

Physical Change• A change that affects one or more

physical properties of a substance.• Does form new substances.• Can often be undone

• Example melted ice can be placed back in refrigerator.

States of Matter

Lutgens and Tarbuck: The Atmosphere

Physical Changes

•Physical changes can be classified as reversible or irreversible.

•All physical changes that involve a change from one state to another are reversible.

•Cutting hair, filing nails, and cracking an egg are examples of irreversible physical changes.

2.1

Chemical Property• A property of matter that describes a substance based on its

ability to change into a new substance with different properties.• Examples:

• 1 pH - The pH scale measures how acidic or basic a substance is.

• a measure of the relative amount of free hydrogen (H+) and hydroxyl ions (OH-).

• The pH of water determines the− solubility (amount that can be dissolved in the water)− biological availability of nutrients (amount that can be

utilized by aquatic life).

• 2. Combustibility - when wood burns• 3. Flammability - when fireworks explode• 4. Reactivity - when iron Oxidizes (rust)

pH scale

Physical Changes

• During a physical change, some properties of a material change, but the composition of the material does not change.

• As gallium melts in a person’s hand, the shape of the sample changes, but the composition of the material does not change.

2.1

Chemical Change

• A change that occurs when one or more substances are changed into entirely new substances with different properties.

• Can’t change back under normal conditions (example – vinegar and baking soda).

• Common Examples:• Reactivity – Oxidation (rust) on a bicycle• pH (Acid / Base) – Effervescent tablets (Alka Seltzer) and your

stomach• Flammability – Burnt wood• Combustibility - Fireworks