Matter & Measurement
§ Measure volume with graduated cylinder
§ Read volume to the lowest part of the meniscus
§ Density = mass/volume
o Mass of a substance = mass of graduated cylinder and substance – mass of graduated cylinder
§ Chemical reactions = a precipitate/solid forms, burning
§ Physical reactions = heating, phase changes (sàlàg)
o In heating from a solid to a liquid the mass is constant
o In heating from a liquid to a gas, mass has evaporated
§ Significant figures
o All numbers 1-9 are significant
o Zeros to the right of the right most integer if there is a decimal are significant
o Adding/Subtracting – answer can contain the least number of decimal places
o Multiplying/Dividing – answer can contain the least number of significant figures (Use this rule in Stoichiometry)
Atomic Structure
§ Isotopic Notation
o Atomic number = number of protons, used to identify the element
o For neutral atoms, electrons = protons
§ Isotopes have the same number of protons/atomic number, but different number of neutrons and mass number
§ Rutherford’s experiment: the atom is mainly empty space and there is a dense positively charged nucleus
§ Mass number (amu) = Protons + Neutrons
§ Ground state electron configuration of an atom: fill to the atomic number 1s22s22p63s23p64s23d104p6
o Noble gases have a full p shell – end in p6
§ Electron configuration of an atom with a charge
o – charge = gained an electron
o + charge = lost an electron
o Electron configuration of O-2 = electron configuration of Ne
o Most commonly formed ion is the element that has a full p6 shell – closest noble gas (He, Ne, Ar, Kr, Xe)
Periodic Table
§ Atomic number = proton number
§ Group 1 = Alkali metals
§ Group 2 = Alkali earth metals
§ Group 7 = Halogens
§ Group 8 = Noble gases
§ Rows = periods
§ Columns = families/groups
o Elements with similar chemical properties are found in the same family/group
§ Left of staircase = metal
§ On staircase = metalloid (properties of both metals and nonmetals)
§ Right of staircase = nonmetals
§ Most reactive metal has the lowest ionization energy
§ Most reactive nonmetal has the highest electronegativity
§ Least reactive elements are the noble gases – no electronegativity values
§ Electronegativity & Ionization energy increases to the right and up
§ Atomic Radius increases to the left and down
§ Valence electron # = group #
Chemical Bonding
§ Ionic compounds = metal + nonmetal
o Transfer of an electron from one atom to another
o Electrostatic attraction between two ions
o Electrolytes conduct electricity when ions are dissolved
§ Covalent compouds = nonmetal + nonmetal
o Sharing of electrons
§ Nonpolar: = sharing
§ Polar: un= sharing
· Water has polar covalent bonds between H & O (hydrogen bonding between two water molecules)
o Lewis dot structures – number of valence electrons = group # for groups 1A-8A
§ VSEPR Theory/Shapes (shape is determined by the number of bonding and nonbonding/lone pairs around the central atom)
o Linear – 2 bonds, example: O2
o Tetrahedral – 4 bonds, example: CCl4
o Trigonal planar – 3 bonds, example: BF3
o Angular/bent – 2 bonds & 2 lone pairs, example: H2O
o Trigonal pyramidal – 3 bond & 1 lone pair, example: NH3
Nomenclature/ Chemical Reactions
§ Count the number of atoms in compound
§ 7 diatomics – H2, O2, N2, Cl2, Br2, I2, F2
§ Prefixes: mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
§ Criss-cross method – switch the charges, drop them down and make them subscripts
o Charges: 1A-3A = + group #
4A & 8A = no charge
5A-7A = group # - 8 (negative charge)
§ Naming rules:
o End in –ide when only 2 elements
o Transition metals have a + roman numeral charge. Ex: Iron (II) = Fe+2
§ Types of reactions
o Double replacement: AB + CD à AD + CB
§ Predict products: Add cation A to the anion D, add the cation C to the anion B
§ Demonstrated by two reactants forming two new products
o Decomposition: AB à A + B
§ Demonstrated by a compound decomposing
o Synthesis: A + B à AB
o Single Replacement: AB + C à AC + B
o Combustion – hydrocarbon + O2 à CO2 + H2O
§ Balancing equations
o Law of Conservation of Matter – Matter is conserved, it cannot be created or destroyed
o Mass and number of atoms of the reactants stays the same in the product
Stoichiometry
§ 1 mole = Molar Mass
§ 1 mole = 22.4 L of gas
§ 1 mole = 6.02 x 1023 molecules
§ Gram-molecules: (g of x /MM of x) * (6.02x1023 molecules)
§ Gram-gram: (g of x /MM of x) * (moles y/moles x) * (MM of y/moles y)
§ Gram-volume: (g of x /MM of x) * (moles y/moles x) * (22.4L of y/moles y)
§ Volume-grams: (L/22.4 L of x) * (moles y/moles x) * (MM of y/moles of y)
§ Percent error: (experimental – theoretical) / theoretical * 100
o Sources of error: spillage
§ Empirical formula: Convert % to g (simply g = %). Divide each by atomic mass of that element = moles. Divide each by lowest mole number. That number = subscript for that element.
§ Mass is conserved
Behavior of Gases
§ Rapid, random molecular motion
§ Increase temperature of a confined gas, increases the number of collisions inside a container, increases the pressure
§ Boyle’s law – pressure & volume, produces a curved graph with a negative slope
§ Combined gas law: P1V1/T1 = P2V2/T2
Acids/Bases/Solutions
§ H2SO4 – Sulfuric Acid
§ Bases turn red & blue litmus paper blue
§ Phenolphthalein indicates pH 8-10 and turns solution pink
§ pH = -log[H+]
§ Unsaturated – can continue to add more solute, solute disappears after it is added to solvent
§ Supersaturated – too much solute
§ Saturated – just enough solute, cannot add any more
§ Solute vs. Solvent (water is always the solvent) 1M CuSO4 – water is solvent, CuSO4 is solute
§ Molarity of Solution = moles solute/L of solution
o If given grams – convert grams to moles by dividing by the Molar Mass
§ Neutralization: Acid + Base à Water + Salt
o #H+ x MAVA à #OH- x MBVB
Thermochemistry
§ Energy diagrams for exothermic reactions: energy of products is less than reactants
§ Energy diagrams for endothermic reactions: energy of products is more than reactants
§ Heating graphs: Increase of temperature over time
§ Cooling graphs: Decrease of temperature over time
§ Phase change occurs at plateaus of heating/cooling graphs
§ Catalysts speed up the reaction rate and lower the activation energy
Compounds
§ CuCl2 – Copper (II) Chloride
§ H2SO4 – Sulfuric Acid