CHAPTER 2

MATTER

ELEMENTS & ATOMS

• Element is a substance that cannot be broken down
• Atoms are the smallest unit of an atom
• Each element is made up of one atom

MOLECULE & COMPOUND

• Molecule is a group of atoms that are held together by chemical forces
• Molecule is the smallest unit that can be by itself
• Each molecule of a compound contains 2+ elements chemically combined

PURE SUBSTANCE & MIXTURE

• A pure substance is a either a single element or a single compound that has def
• Definite chemical and physical properties.
• Mixture- combination of 2+ substances that are not chemically combined
• Elements and compounds are pure substances but mixtures are not.

HETEROGENOUS & HOMOGENOUS

• Heterogenous mixture-substances are not evenly distributed
• Homogenous mixture-substances are evenly distributed
• Example: water is homogenous and oil mixed with water is heterogenous.

DENSITY

• The ratio of the mass of a substance and the volume of the substance.
• Mass/Volume=Density
• Example: If the density is less than water it will float if it is greater it will sink.

PHYSICAL & CHEMICAL CHANGE

• Physical change-a change of matter from one form to another but..
• Without a change in chemical properties.
• Chemical change-one substance changes into new one by combining...
• With other elements or breaking apart a new substance.
• Example: physical-crushing, cutting. Chemical-flammability, reactivity.

THINGS TO REMEMBER

• Every sample of matter is either a element, compound, or a mixture.
• Compounds have unique properties
• Miscible are substances that can be mixed while immiscible cannot
• Physical properties can help identify substances
• Chemical formulas represent compounds

THE END