1 Atomic Structure Major Terms and Topics Atoms are composed of protons neutrons and electrons Protons have a positive charge neutrons have no charge neutral and electrons have a negative charge The atomic number Z represents the number of protons in an atom while the mass number A represents the total number of protons and neutrons Isotopes are atoms of the same element with different numbers of neutrons 2 Periodic Table chemical properties 3 Chemical Bonding The periodic table organizes elements based on their atomic number and Elements are arranged in rows periods and columns groups Properties of elements vary predictably across periods and down groups Ionic Bonds Formed by the transfer of electrons from one atom to another resulting in the formation of ions Covalent Bonds Formed by the sharing of electrons between atoms Metallic Bonds Formed in metals where electrons are delocalized and shared among all atoms in the metal lattice 4 Chemical Reactions Chemical reactions involve the breaking and forming of chemical bonds Types of reactions include synthesis decomposition single replacement double replacement and combustion reactions Chemical equations represent the reactants and products of a chemical reaction 5 Stoichiometry Stoichiometry involves the quantitative relationships between reactants and products in a chemical reaction Mole concept 1 mole of any substance contains Avogadro s number of particles Molar mass The mass of one mole of a substance expressed in grams per mole 6 022 10 23 g mol Stoichiometric calculations involve using balanced chemical equations to determine the amounts of reactants consumed and products formed 6 Gas Laws Boyle s Law States that at constant temperature the volume of a gas is inversely proportional to its pressure P1V1 P2V2 Charles s Law States that at constant pressure the volume of a gas is directly proportional to its temperature V1 T1 V2 T2 Avogadro s Law States that at constant temperature and pressure the volume of a gas is directly proportional to the number of moles of the gas V1 n1 V2 n2 Ideal Gas Law Describes the behavior of ideal gases under various conditions PV nRT 7 Solutions solvent solute and solvent 8 Acids and Bases Solutions are homogeneous mixtures composed of a solute dissolved in a Concentration units include molarity M molality m and mole fraction Factors affecting solubility include temperature pressure and the nature of Acids donate protons H ions in aqueous solution while bases accept protons OH ions or other species pH is a measure of the acidity or basicity of a solution with pH 7 indicating acidity pH 7 indicating neutrality and pH 7 indicating basicity Strong acids and bases completely dissociate in water while weak acids and bases only partially dissociate Atomic Structure a How many protons neutrons and electrons are present in an atom of carbon 12 Practice Problems b Write the electron configuration for sulfur S Chemical Bonding a Draw the Lewis structure for methane CH b Determine the type of bond ionic covalent or metallic present in sodium chloride NaCl Chemical Reactions a Write a balanced chemical equation for the reaction between sulfuric acid H SO and potassium hydroxide KOH b Identify the type of reaction synthesis decomposition single replacement double replacement for the following equation 2H O 2H O Stoichiometry a How many moles of oxygen gas O are required to completely react with 5 moles of hydrogen gas H in the following equation 2H O 2H O b Calculate the mass of sodium chloride NaCl produced when 4 5 moles of sodium Na react with excess chlorine Cl according to the equation 2Na Cl 2NaCl Gas Laws a If the volume of a gas is 3 0 L at a pressure of 2 0 atm what will be the volume of the gas if the pressure is increased to 3 5 atm assuming constant temperature b A sample of gas occupies 22 4 L at 0 C and 1 atm pressure What volume will it occupy at 25 C and 1 atm pressure Solutions a Calculate the molarity of a solution prepared by dissolving 25 grams of sodium hydroxide NaOH in enough water to make 500 mL of solution b What is the mole fraction of ethanol C H OH in a solution containing 50 grams of ethanol and 150 grams of water Acids and Bases a Calculate the pH of a solution with a hydrogen ion concentration of 1 0 10 3 M b Identify the conjugate acid base pairs in the following reaction HCO H O CO H O Thermodynamics a Define endothermic and exothermic reactions b Calculate the change in enthalpy H for a reaction if 50 grams of a substance undergoes a temperature change from 25 C to 100 C given that its specific heat capacity is 4 18 J g C