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Do Now

Do Now. If Al atoms weigh 27, and O atoms weigh 16, what is the mass of Al 2 O 3 ? Draw a picture of an atom, labeling the Nucleus and Orbitals, and indicate the location of the Protons, Neutrons, and Electrons. Midterm Review!!. Subatomic Particles.

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Do Now

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  1. Do Now If Al atoms weigh 27, and O atoms weigh 16, what is the mass of Al2O3? Draw a picture of an atom, labeling the Nucleus and Orbitals, and indicate the location of the Protons, Neutrons, and Electrons

  2. Midterm Review!!

  3. Subatomic Particles • Nucleus: Proton: +1 charge, mass 1 amu Neutron: 0 charge, mass 1 amu • Orbitals: Electrons: -1 charge, mass 0 amu • In what part of an atom is all of its mass located?

  4. Atomic Number & Mass • Atomic Number: number of Protons • Atomic Mass: sum of Protons & Neutrons • Usually has a decimal because it’s an average • If Aluminum’s Atomic Number is 13, how many protons does it have? • Aluminum’s Atomic Mass is 27. Given its number and mass, how many Neutrons does it have?

  5. Isotopes • Types of atoms with different numbers of Neutrons, thus have different mass • E.g. C-12, C-13, C-14 are Isotopes of Carbon • Written like: • Carbon-14 Name + Mass • C-14 Symbol + Mass • 14C Mass & Symbol • 614C Atomic Number, Mass, Symbol

  6. Formula Mass • Add the atomic masses of all atoms in a compound • Al2(OH)6 contains • 2 Al atoms, each weigh 27 • 6 O atoms, each weigh 16 • 6 H atoms, each weigh 1 • Total Mass: 156

  7. Electrons • Electrons live in Orbitals • Orbitals are areas around atoms in which you are most likely to find an Electron • In a normal atom, the number of Protons = the number of Electrons • Ions have different numbers of Protons and Electrons, and have an overall charge (e.g. +2)

  8. Gold Foil Experiment • Ernest Rutherford’s “Gold Foil Experiment” showed that atoms: • Are mostly empty space • have a dense, positively-charged nucleus

  9. Heating & Energy • Temperature is a measure of the average Kineticenergy of particles in a substance. • As Temperature increases, average Kinetic energy increases • Solids have lower kinetic energy than liquids, and liquids have less than gases. • Potential energy does not change

  10. Heating & Energy • Endothermic • Energy goes in • e.g. melting a solid, boiling a liquid • Exothermic • Energy goes out • e.g. freezing a liquid, condensing a gas

  11. Heating & Energy • Heat moves from hotter things to colder things. • Temperatures balance out, eventually reach equilibrium

  12. Phases of Matter • Solid • definite shape, definite volume • Liquid • No definite shape, definite volume • Gas • No definite shape, no definite volume

  13. Reaction Types • Single Replacement • Ag + NaOH -> Na + AgOH • Double Replacement • AgNO3 + NaOH -> NaNO3 + AgOH • Synthesis • Ag + Cl -> AgCl • Decomposition • AgCl -> Ag + Cl

  14. Moles • Gram Formula Mass = 1 Mole • “What is the mass of X Moles of Y?” • # of Moles x Gram Formula Mass • “How many Moles in X grams of Y?” • Given Mass ÷ Gram Formula Mass

  15. Percent Composition “What is the percent by mass of Fe in Fe2O3?” • Total mass of Fe in the compound: • 2 Fe atoms, each weigh 56 = 112 • Total mass of compound • 2 Fe atoms, each weigh 56 =112 • 3 O atoms, each weigh 16 = 48 • Total mass 160 • Mass of Fe ÷ Total Mass x100% • 112 ÷ 160 = 0.7 • 0.7 x 100% = 70%

  16. Empirical Formula • Smallest ratio of numbers within a compound • C6H6 has empirical formula of CH • C2H2 has empirical formula of CH • C4H10 has empirical formula of C2H5 • C3H21 has empirical formula of CH7

  17. Empirical Formula • “A compound has a molecular mass of 54 and an empirical formula of C2H3. What is its molecular formula?” • C2H3 has a formula mass of 27 • 54 ÷ 27 = 2 • C2x2H3x2 = C4H6

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