Chapter 2 Matter. The “Stuff” of which the universe is composed

Chapter 2

Matter

• Matter • The “Stuff” of which the universe is composed

• Atoms

• Compounds

• The fundamental unit of an element

• Substances made by bonding atoms together in certain ways

• Elements

• Structural form

• Substances that contain only one type of atom, like carbon

• Some elements have different structural forms but are still the same element, like carbon

• Diamond

• Graphite

Physical vs. Chemical

• Physical Properties

• Characteristics of a substance that can change without the substance becoming a different substance• Odor, color, volume, state, density, melting point and boiling point

• Chemical properties

• Ability of a substance to change to a different substance•Wood burning, rusting of a car, digestion of food, growth of grass in the yard

• Physical Change

• Does not affect the composition of a substance•Water freezing or boiling… still H2O

• Chemical Change

• Completely changes a substance into a different substance• Electrolysis, the decomposition of water using an electrical current, splits H2O into H2 & O2

Physical or ChemicalProperty?

• The boiling point of liquid A is 78oC• A diamond is very hard• Sugar ferments to form

alcohol• A metal wire conducts an

electric current

Physical or ChemicalProperty?

• Gallium metal melts in your hand. • Platinum does not react with

oxygen at room temperature.• The paper is white.• The Statue of Liberty, which

is made of copper, has turned green over the years.

Physical or ChemicalChange?

• Iron metal is melted.• Iron combines with oxygen to form rust.• Wood burns in air.• A chocolate chip cookie is broken into

small pieces.• Milk turns sour.• Wax is melted over a flame, catches fire

and burns.

ENOUGH FOR TODAY!!!!!!

YES!!!!!

Mixtures & Pure Substances

• Mixture

• Alloy

• Something that has a variable composition

• Coffee, Soda, Wood, Water from a well

• Mixtures of metals• 24 Gold is pure; 14-K

& 18-K gold contain mixtures of gold, silver and Copper

• Common Alloys of Gold

• Electrum (Cu, Ag)• Rhodite

(Rhodium)• Rose Gold (Cu)• White Gold (Ni,

Palladium)

• Pure Substances • Always has the same composition

Homogeneous vs. Heterogeneous

• Homogeneous

• Heterogeneous

• The same throughout

• Salt dissolved in water; sugar dissolved in tea

• Regions that have different properties

• Sand in water

Separation of Mixtures

• Distillation

• Filtration

• Boiling, collecting the steam and leaving the solid behind

• Distilled water removes impurities

• Pouring through a piece of filter paper to collect the solid and allow water to pass through