This document provides an introduction to basic chemistry concepts including the structure of atoms, atomic mass, and quantities. Atoms consist of a dense positively charged nucleus made up of protons and neutrons surrounded by an electron cloud of negatively charged electrons. The number of protons determines the element. Atomic mass is measured in atomic mass units and is based on the number of protons and neutrons. Elements can have different isotopes that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. Quantities in chemistry such as moles and molarity are also introduced.

1. Introduction to Chemistry Adam Rohde

2. Particles Protons: Positively charged particles Neutrons: Neutral particles Electrons: Negatively charged particles

3. Nucleus Dense center of the atom Positively charged Consists of protons and neutrons Determines what the element is Contains most of the mass

4. Electron Cloud Orbits the nucleus Consists of electrons Takes up most of the space Does not contribute to atomic mass

5. Atomic Mass Number of protons and neutrons Atomic mass units (amu) 4 protons + 3 neutrons = 7 amu Electrons are not counted

6. Nuclear Force Protons repel each other Held together by strong nuclear force Have to be extremely close Exchange mesons

7. Atomic Charges Relative to protons and electrons # of protons > # of electrons: + charge # of electrons > # of protons: - charge # of protons = # of electrons: neutral Neutrons are not counted

8. Elements Depend on # of protons # of protons decides placement on the periodic table Can have different charges Can have different # of neutrons

9. Ions Same elements Different charges Hydrogen with 2 electrons: - 1 Hydrogen with 1 electron: neutral Hydrogen with 0 electrons: + 1

10. Isotopes Same element Different masses Hydrogen with 1 neutron: 2 amu Hydrogen with 0 neutrons: 1 amu

11. Periodic Atomic Mass Mass displayed on the periodic table Average mass of the isotopes Used when determining quantities of molecules

12. Quantities Mass (grams) Moles Molarity

13. Avogadro’s Number Used often if chemistry Number of molecules in 1 mole 6.022 x 10e23

14. Moles Can be determined from mass Grams / atomic mass Ex: 28g of N / 14 amu = 2 moles

15. Molarity Concentration in a solution # of moles / liters of solution Ex: 2 moles of HCl / .5L = 4M

16. Review Structure of atoms Charges of atoms Mass of atoms Quantities

17. References ion. (2009). In Merriam-Webster Online Dictionary. Retrieved October 1, 2009, from http://www.merriam-webster.com/dictionary/ion isotope. (2009). In Merriam-Webster Online Dictionary. Retrieved October 1, 2009, from http://www.merriam- webster.com/dictionary/isotope The Strong Nuclear Force. (n.d.). Retrieved October 1, 2009, from http://aether.lbl.gov/elements/ stellar/strong/strong.html Weisstein, E. W. (n.d.). l. Retrieved October 1, 2009, from http://scienceworld.wolfram.com/physics/ AvogadrosNumber.html