1. UNIT 3: DAY 1 AND DAY 3 ATOMIC STRUCTURE

2. ATOM, ELEMENTS, AND COMPOUNDS Atoms are the smallest unit of matter In classification, all atoms are elements Compounds are made of two or more atoms/elements

3. Electrons (- charge) Protons (+charge) Neutrons (no charge)

4. Orbitals Nucleus Electron Cloud

5. IDENTIFYING ATOMS The identity of an element is determined based on number of protons in the element. This number is also known as an atomic number. Most of the mass of an atom is in the nucleus (where the protons and neutrons are). Atomic number and atomic weight (mass) can be found on the periodic table for the most abundant version of an element.

6. ATOM, ISOTOPE, AND ION Atom = smallest unit of an element Neutral atom = atom where the number of protons equals the number of electrons. Isotope = different possible versions of each element. Isotopes have the same numbers of protons, but different numbers of neutrons. Ion = atom or molecule in which the total number of electrons is not equal to the total number of protons.

7. GENERAL INFORMATION FOUND ON THE PERIODIC TABLE

8. ISOTOPIC SYMBOL Z A X Z is the atomic mass (weight) A is the atomic number E is the atomic symbol (from PT) X is the charge of the element

9. A SECOND NOTATION Name of the element – mass number Examples carbon-14 oxygen-16

10. HOW DO YOU DETERMINE THE FOLLOWING INFO FOR A PARTICULAR ELEMENT: Atomic number = # of protons (from PT) Mass number = # of protons plus # of neutrons Protons = same as atomic # Neutrons = mass # - atomic # (# of protons) Electrons = same as atomic # (plus any (-), take away any (+))

11. EXAMPLE PROBLEM 1 How many electrons does a neutral atom of carbon have?

12. EXAMPLE PROBLEM 2 How many protons does an atom of oxygen have?

13. EXAMPLE PROBLEM 3 How many neutrons does the atom carbon-14 have?

14. LEARNING CHECK Element Atomic Number Number of Protons Number of Electrons Mass Number Number of Neutrons lithium carbon-12 carbon-14 Fe F