1. CHAPTER 2 CONCURRENT ENROLLMENT CHEMISTRY

2. ATOMS ELECTRONS ELECTRONS Thomson found a charge to mass ratio of an electron to be -1.76 x 10 8 C/g Thomson found a charge to mass ratio of an electron to be -1.76 x 10 8 C/g Millikan’s oil drop experiment determined the electron mass to be 9.11 x 10 -31 kg Millikan’s oil drop experiment determined the electron mass to be 9.11 x 10 -31 kg RADIATION RADIATION Becquerel discovered radioactivity Becquerel discovered radioactivity Three type of radiation Three type of radiation Gamma (γ) rays are high-energy “light” Gamma (γ) rays are high-energy “light” Beta (β) rays are high-speed electrons Beta (β) rays are high-speed electrons Alpha (α) rays are a 2+ charged He nucleus Alpha (α) rays are a 2+ charged He nucleus

3. COMPONENTS Rutherford’s gold foil experiment Rutherford’s gold foil experiment Atoms have a nucleus Atoms have a nucleus Atoms are made up mostly of space Atoms are made up mostly of space Protons exist in the nucleus with a + charge Protons exist in the nucleus with a + charge Electrons mass is 9.11 x 10 -31 kg, the charge is - Electrons mass is 9.11 x 10 -31 kg, the charge is - Protons mass is 1.66 x 10 -27 kg, the charge is + Protons mass is 1.66 x 10 -27 kg, the charge is + Neutrons mass is 1.67 x 10 -27 kg, there is no charge Neutrons mass is 1.67 x 10 -27 kg, there is no charge AMU means 1.66053 x 10 -27 kg, so a proton and neutron are 1 AMU each AMU means 1.66053 x 10 -27 kg, so a proton and neutron are 1 AMU each Atoms are small Atoms are small Diameters between 1 x 10 -10 m to 5 x 10 -10 m, Ǻ = 1 x 10 -10 m so it is 1A to 5A Diameters between 1 x 10 -10 m to 5 x 10 -10 m, Ǻ = 1 x 10 -10 m so it is 1A to 5A Isotopes have the same number of protons but different number of neutrons Isotopes have the same number of protons but different number of neutrons

4. COMPOUNDS AND ELEMENTS Compounds are made up of elements and the number of each element Compounds are made up of elements and the number of each element H 2 O H 2 O Atomic weights are an average of all the isotopes for that element Atomic weights are an average of all the isotopes for that element Atomic weight = (% isotope#1)(mass)+(% isotope#2)(mass) Atomic weight = (% isotope#1)(mass)+(% isotope#2)(mass) 100 100

5. MOLES An amount of a substance, similar to dozen. An amount of a substance, similar to dozen. One dozen eggs would not weigh the same as one dozen horses, the same is true in atoms One dozen eggs would not weigh the same as one dozen horses, the same is true in atoms One mole of anything is 6.02 x 10 23 particles of that substance. This is known as Avogadro’s number One mole of anything is 6.02 x 10 23 particles of that substance. This is known as Avogadro’s number If you times magnesium atoms mass to this number, you will get 24.3 g per one mole. This is the atomic mass of magnesium. If you times magnesium atoms mass to this number, you will get 24.3 g per one mole. This is the atomic mass of magnesium.

6. CHEMICAL FORMULAS All compounds have constant ratios. This means that the number of elements in a compound remain constant All compounds have constant ratios. This means that the number of elements in a compound remain constant One mole of water would then contain, two moles of hydrogen and one mole of oxygen One mole of water would then contain, two moles of hydrogen and one mole of oxygen One molecule of water would contain, two atoms of hydrogen and one atom of oxygen One molecule of water would contain, two atoms of hydrogen and one atom of oxygen Because of this law you can find mass percentage of any element in any given compound Because of this law you can find mass percentage of any element in any given compound