1. What is matter? Matter – anything that occupies space and has mass –Composed of chemical elements Element – cannot be broken down into other substances –92 natural elements EX – oxygen, carbon, copper –Each element has a symbol from its name EX - O, C, Cu –Essential to life…(96%) O, C, H, N –Trace elements…(4%) Ca, P, K, S

2. Compounds Compound – a substance containing 2 or more elements in a fixed ratio –More common than elements NaCl = table salt H 2 O = water Glucose Sucrose

3. ATOMS Atom – –Indivisible – Greek –Smallest unit of matter that retains the properties of an element Atomic Structure – *Nucleus – central core of the atom, contains protons and neutrons *Proton – positively charged *Neutron – no charge *Orbitals - outside the nucleus *Electron – negatively charged Attraction between protons and electrons keep the electrons nearby the nucleus.

4. How is one element different from another element? Atomic number – same as the number of protons –Oxygen has 8 protons If the atom is electrically neutral (number of protons = number of electrons) then the atomic number also is the same as the number of electrons. Mass number – sum of the numbers of protons and neutrons in a nucleus

5. Periodic Table of Elements