Chemistry lecture 4

• Chemical Reactions


  1. Valence electrons are involved as shared or donated species

  2. Atoms are re-arranged during a chemical reaction, they are not changed by the reaction

  3. Reactants react to produce end products
• Reactions


  Reactants → Product

  Arrow means reaction involving reactants taking place, resulting in products
• General Chemical Reaction


  aA(s) + bB(g) → cAB(s)

  A,B-reactants, AB-product, abc-moles-specific amount where 1 mole =6.02 * 10^23 particles

  Subscripts depict state, s-solid, g-gas
• Specific Example


  • 2Na(s) + Cl2(g) → 2NaCl(s)
• Nuclear Reaction


  Two nuclei, or else a nucleus of an atom and a subatomic particle (such as a proton, or high energy electron) from outside the atom, collide to produce products different from the initial particles
• Specific Example 1


  • The formation of a heavier helium nuclide by the fusing of deuterium and tritium
• Specific Example 2


  • Lithium 6-Deuterium Reaction resulting in two alpha particle (2 helium atoms)

  6Li + 2H → 4He + 4He
• Binary Compounds


  When a pair of elements form more than one type of covalent compound, Greek prefixes are used to indicate how many of each element are in a compound
• Greek Prefixes


  • mono 1
  • di 2
  • tri 3
  • tetra 4
  • penta 5
  • hexa 6
  • hepta 7
  • octa 8
  • deca 10
• Determining order of elements in binary compound

  The element that comes first in the following list "goes" first (is less electronegative): B, Si, C, Sb, As, P, N, H, Te, Se, S, I, Br, Cl, O, F
• Naming binary compounds


  The more electronegative element is written last and its ending is changed to -ide
• Examples of binary compound naming

  • N2O dinitrogen monoxide

  NO nitrogen monoxide

  N2O3 dinitrogen trioxide

  N2O5 dinitrogen pentoxide
• The prefix mono is never used for naming the first element of a compound
• The final "o" or "a" of a prefix is often dropped when the element begins with a vowel
• H2O is always called water, and NH3 is always called ammonia
• Ionic Compounds


  Metals give up electrons to form positively charged cations

  Non-metals gain electrons to form negatively charged anions

  Ionic compounds are formed from the Coulombic interaction between cations and anions
• Naming Ionic Compounds


  1. The name of the cation comes first followed by the name of the anion, changing the name of the anion to end in -ide for monotomic anions
  2. In cases where the metal can form cations of differing charges, the positive charge (oxidation number) is given by a roman numeral in parentheses
• Examples of Ionic Compound Naming

  • NaCl sodium chloride

  ZnI2 zinc iodide

  NaNO3 sodium nitrate

  Ag2CO3 silver carbonate

  (NH4)2SO4 ammonium sulfate

  CuO copper (II) oxide

  Cu2O copper (I) oxide

  Cr2O3 chromium (III) oxide

  MnO4- manganese (VII) oxide
• Oxyanions


  Polyatomic anions containing oxygen
• Naming Oxyanions


  1. The ending -ate is used for the most common oxyanion of a given element
  2. The ending -ite is used for the oxyanion with the same charge, but one less oxygen than the -ate oxyanion
  3. The prefix per- is used if there is an oxyanion with the same charge but one more oxygen than the -ate oxyanion, while the prefix hypo- is used if there is an oxyanion with the same charge but one less oxygen than the -ite oxyanion
• Examples of Oxyanion Naming


  • NO3- Nitrate ion

  SO42- Sulfate ion

  CO32- Carbonate ion

  PO43- Phosphate ion

  ClO3- Chlorate ion

  NO2- Nitrite ion

  SO32- Sulfite ion

  PO33- Phosphite ion

  ClO2- Chlorite ion

  ClO4- Perchlorate ion

  ClO3- Chlorate ion

  ClO2- Chlorite ion

  ClO- Hypochlorite ion
• Acids


  A compound that dissolves in water to release H+ ions
• Naming Acids


  1. When the anion ends in -ide, change the ending to -ic and add the prefix hydro- to derive the name of the acid
  2. When the anion ends in -ate, change the ending to -ic to derive the name of the acid
  3. When the anion ends in -ite, change the ending to -ous to derive the name of the acid
• Examples of Acid Naming

  • Anion = chloride (Cl-) → hydrochloric acid (HCl)

  Anion = bromide (Br-) → hydrobromic acid (HBr)

  Anion = sulfide (S2-) → hydrosulfuric acid (H2S)

  Anion = chlorate (ClO3-) → chloric acid (HClO3)

  Anion = sulfate (SO42-) → sulfuric acid (H2SO4)

  Anion = nitrate (NO3-) → nitric acid (HNO3)

  Anion = phosphite (PO33-) → phosphorous acid (H3PO3)

  Anion = chlorite (ClO2-) → chlorous acid (HClO2)

  Anion = hypochlorite (ClO-) → hypochlorous acid (HClO)
• Complexes


  A complex ion is named to indicate the number and type of attached ligand groups, the central metal cation and its oxidation state, and the overall charge
• Example of Complex Naming

  • [Fe(H2O)6]3+ - hexaaquairon(III) ion

  [Fe(H2O)6]Cl3 - hexaaquairon(III) chloride