Adam Rohde

Particles  Protons: Positively charged particles  Neutrons: Neutral particles  Electrons: Negatively charged particles

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

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

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

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

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

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

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

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

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

Quantities  Mass (grams)  Moles  Molarity

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

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

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

Review  Structure of atoms  Charges of atoms  Mass of atoms  Quantities

References  ion. (2009). In Merriam-Webster Online Dictionary. Retrieved October 1, 2009, from  isotope. (2009). In Merriam-Webster Online Dictionary. Retrieved October 1, 2009, from webster.com/dictionary/isotope  The Strong Nuclear Force. (n.d.). Retrieved October 1, 2009, from stellar/strong/strong.html  Weisstein, E. W. (n.d.). l. Retrieved October 1, 2009, from AvogadrosNumber.html