Chemistry - Fall Semester Final topics Mr. Weissbard

Naming Chemical Compounds

Rule 1– If two identical elements combine then the name doesn’t change These compounds are called “diatomic” meaning they have 2 atoms. Diatomic molecules are gasses at room temperature. H2 N2 O2 F2 Cl2 Br2 I2

Name these compounds Sodium + chlorine Magnesium + fluorine Rule 2 – When two elements join and one is a halogen, oxygen or sulphur the name ends with ____ide e.g. Magnesium + oxygen —> magnesium oxide Sodium + chlorine Magnesium + fluorine Lithium + iodine Chlorine + copper Oxygen + iron Name these compounds

Name these compounds KBr LiCl CaO MgS KF

e.g. Sodium + hydrogen + oxygen —> Sodium hydroxide Rule 3 – When three or more elements combine and two of them are hydrogen and oxygen the name ends with hydroxide e.g. Sodium + hydrogen + oxygen —> Sodium hydroxide Potassium + hydrogen + oxygen Lithium + hydrogen + oxygen Calcium + hydrogen + oxygen Mg(OH)2 may also be called Magnesium di-hydroxide

e.g. Copper + sulphur + oxygen Copper sulphate Rule 4 – When three or more elements combine and one of them is oxygen the ending is _____ate e.g. Copper + sulphur + oxygen Copper sulphate Calcium + carbon + oxygen Potassium + carbon + oxygen Calcium + sulphur + oxygen Magnesium + chlorine + oxygen Calcium + oxygen + nitrogen

Name these compounds AgNO3 H2SO4 K2CO3

Some common covalent and ionic compounds Covalent formulae H2O Water CO2 Carbon Dioxide NH3 Ammonia H2 Hydrogen O2 Oxygen N2 Nitrogen SO2 Sulfur Dioxide Ionic formulae NaCl Sodium Chloride CaCl2 MgO HCl H2SO4 HNO3 NaOH Ca(OH)2 CaCO3 Al2O3 Fe2O3

Avogadro’s Number In 1865, Avogadro determined that a gasses properties were determined by the number of gas particles in a sample and not the specific properties of any particular gas molecule. Later, in 1909, Perrin determined that there should be a unifying constant relating atomic mass and a measurable quality such as a sample’s weight in grams. Since this number would apply to Avogadro’s principle, Perrin named it Avogadro’s Number. It was not until the 1950’s that accurate measurements of Avogadro’s number became possible. The measurements were based on x-ray diffraction of exactly 12 grams of Carbon12. Today, Tantalum is used as the standard. Avogadro’s number is 6.02 x 10^23 particles (atoms or compounds) = 1 mole.

Using Avogadro’s Number Find the weight of 1 mole of each of these chemicals Hint: Total up the molecular weights of each component H2 He 12C H2O Al2O3

Find the number of moles If you know the weight of a sample and its chemical composition, you can find the number of moles in a sample. simply total up the elements in a compound, multiply each by their weight to get the molecular weight of the compound next divide the weight of the sample by the molecular weight example: 18 grams of H2O is 1 mole example 36 grams of H2O is 2 moles (notice the relation between MOLEcular weight and the unit MOLE)