Chapter 2 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 H 2 O

Chemical Change Completely changes a substance into a different substance Electrolysis, the decomposition of water using an electrical current, splits H 2 O into H 2 & O 2

Physical or Chemical Property? The boiling point of liquid A is 78 o C A diamond is very hard Sugar ferments to form alcohol A metal wire conducts an electric current

Physical or Chemical Property? 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 Chemical Change? 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