1. Chapter 4 Notes Part II Elements & Compounds

2. Matter Pure Substance (uniform composition) Mixture (variable composition) Elements (only one kind of atom) Compounds (atoms in consistent proportions) Homo- geneous (uniform distribution) Hetero- geneous (non-uniform distibution)

3. Pure Substances made of only one kind of material has definite properties the same throughout Examples = iron, aluminum, water, sugar, & table salt

4. Element the simplest pure substance made of atoms properties are specific to that element written as a symbol

5. Chemical Symbols a system of representing the elements one or two letters, 1 st letter is always capitalized some symbols are based on the Latin names Au = aurum (gold) Ag = argentum (silver)

6. Compounds pure substances that are made of more than one element two or more elements are chemically combined can have different properties than its elements Examples = sugar (C 6 H 12 O 6 ) water (H 2 O) salt (NaCl)

7. Breaking Down Compounds unlike elements, the compounds can be broken down into simpler substances heating can separate some compounds into their elements electric energy can break down compounds

8. Molecules made of tow or more atoms chemically bonded together the smallest particle of a compound that has all the properties of that compound

9. Chemical Formula shorthand way of representing chemical substances like molecules & compounds tells how many of each atom are bonded Compound Example = H 2 O = water has two hydrogen atoms & one oxygen atom bonded together Molecule Example = O 2 = free oxygen has two oxygen atoms bonded together

10. Chemical Equation used to describe a chemical process or chemical reaction 2H 2 + O 2 → 2H 2 O

11. Review ? ?? Made of only one kind of atom Made of more than one kind of atom Made of more than one kind of molecule Cannot be broken down by chemical means Can be broken down by chemical means Can be separated by physical means Has same properties as atoms making it up Has different properties from elements making it up Has same properties as substances making it up Has same properties throughout Has different properties throughout