Semester One Final Exam Review Chemistry

Models of the Atom Dalton Thomson Rutherford Bohr Quantum None – a solid sphere Electrons – negative Protons - positive Thomson Electrons – negative Protons – positive Nucleus of protons in center Rutherford Electrons – negative Protons – positive Neutrons - neutral Nucleus of protons Electrons orbit at different levels Bohr Electrons – negative Protons – positive Neutrons – neutral Nucleus of protons and neutrons Electrons in clouds Quantum

Information from the Periodic Table 3 atomic number = number of protons (unique to element) = number of electrons Li lithium atomic weight = average mass of all isotopes 6.94 mass number (whole number) = protons + neutrons

Isotopes Isotopes: atoms of the same element with different numbers of neutrons To find possible isotopes: round the atomic weight down to the nearest whole number and up to the nearest whole number neutron

Nuclear Reactions – Alpha and Beta Decay Alpha Decay: Beta Decay: Key to remember: the numbers on both sides of the arrow MUST balance (just like in chemical equations)

Valence Electrons Valence electrons: electrons in the outermost (highest) energy level For all elements EXCEPT THE TRANSITION METALS, use the column/group to determine the number of valence electrons.

Electron Configurations

Shorthand Electron Configurations Instead of writing out all the filled subshells, you can use a shorthand (or noble gas) configuration. Use the last noble gas as your starting point. EXAMPLE: Bromine’s full electron configuration: 1s22s22p63s23p64s23d104p5 Bromine’s shorthand configuration: [Ar]4s23d104p5 Bromine’s shorthand configuration: [Ar]4s23d104p5

Chemical Formula to Name Steps to follow: 1. Ionic or covalent? 2. Covalent: use prefixes 3. Ionic: look for polyatomic ions and transition metals MnO manganese (II) oxide P4O8 tetraphosphorous octaoxide K2CO3 potassium carbonate

Chemical Name to Formula Steps to follow: 1. Ionic or covalent? 2. Covalent: use prefixes 3. Ionic: write ion list and get charges to cancel out Lead (IV) sulfide PbS2 Calcium hydroxide Ca(OH)2 Nitrogen dioxide NO2

element + element → compound Synthesis A + B → AB + → Type of Reaction To identify… element + element → compound Synthesis A + B → AB + → compound → element + element Decomposition AB → A + B → + element + compound → element + compound Single Replacement A + BX → AX + B + → + compound + compound → compound + compound Double Replacement AB + CD → AD + BC + → + Carbon compound + O2 → CO2 + H2O Combustion ALWAYS THE PRODUCTS!

Predicting Products Hints: 1. Identify the type of reaction so you know how many products to find 2. Circle polyatomic ions 3. Ionic compound charges must cancel out! 1. Mg + O2  MgO (synthesis) 2. NaCl + Al(NO3)3  NaNO3 + AlCl3 (double replace.) 3. Sr + H2SO4  SrSO4 + H2 (single replace.)

__AgNO3 + __Cu  __ Cu(NO3)2 + __Ag Balancing Equations Hints: 1. Start by drawing one of each compound and put a box around it. Remember – a capital letter means you have a new element! 2. Leave oxygen for last. __AgNO3 + __Cu  __ Cu(NO3)2 + __Ag

Molar Mass 1. MnBr2 2. Sr(NO3)2 To determine… 1. How many of each atom? 2. Molar mass of each element? 3. Total mass from each element? Then add them all together! 1. MnBr2 2. Sr(NO3)2 Used as a quick review on Day 2

Mole Conversions – a new trick! Use the box method! How many moles does a 25.2 gram sample of CaCl2 contain? grams molar mass moles Used as a quick review on Day 2

Mole Conversions – a new trick! Use the box method! What is the mass of 9.45 mol of Al2O3? grams molar mass moles Used as a quick review on Day 2

Stoichiometry – The Box Method Calculate the number of grams of NH3 produced by the reaction of 11.9 g of nitrogen with an excess of hydrogen. __N2 + __H2 → __NH3 grams molar mass moles