Definitions For flashcards.pdf

Definitions For flashcards Avogadro’s Law equal volumes of gases, under the same conditions of temperature & pressure, contain equal numbers of molecules. Mole is the amount of that substance that contains as many particles (atoms, molecules, or ions) as there are atoms of ¹²C in 12g of ¹²C. Arr...

Definitions For flashcards Avogadro’s Law equal volumes of gases, under the same conditions of temperature & pressure, contain equal numbers of molecules. Mole is the amount of that substance that contains as many particles (atoms, molecules, or ions) as there are atoms of ¹²C in 12g of ¹²C. Arrhenius acid a substance that dissociates in aqueous solution, forming hydrogen ions. Arrhenius base a substance which dissociates in aqueous solution, forming hydroxide ions. Bronsted -Lowry acid a proton donor. Bronsted-Lowry base a proton acceptor. Conjugate acid-base pairs are species which differ by the presence or absence of a proton. Primary Standard a water-soluble substance that is stable & is available in pure form Standard Solution a solution whose concentration is accurately known. Activation Energy is the minimum energy that colliding particles must have for a reaction to occur between them. Autocatalysis is where the product of a reaction becomes a catalyst for the same reaction. Catalyst is a substance that alters the rate of a chemical reaction, but is not used up in the reaction. Effective Collision is one which has sufficient activation energy & results in a product being formed. Heterogeneous Catalysis is where the catalyst is in a different physical phase to the reactants. Rate of Reaction is the change in concentration per unit time of any one reactant or product. Half Life is the time taken for half the atoms in a sample of an isotope to decay. Isotopes are elements with the same atomic number but different mass number. Radioactivity is the spontaneous breaking up of certain unstable nuclei, accompanied by the emission of radiation. Radioisotope is a radioactive isotope. Atomic Number is the number of protons in the nucleus of an atom. Mass Number is the sum of the number of protons & neutrons in the nucleus. Relative Atomic Mass (Aᵣ) is the average mass of an atom of the element relative to 1/12 the mass of an atom of Carbon- 12. Atomic Orbital is the region around the nucleus where the probability of finding an electron is relatively high (>95%). Energy Level is a region of defined energy within an atom that electrons can occupy. Energy Sub-Level is made up of a group of atomic orbitals, all of the same energy Heisenberg’s Uncertainty Principle it is not possible to know the exact position and exact velocity of an electron or other small particle at the same time. Covalent Bond is formed when two non-metal atoms share a pair of electrons. Ionic Bond is the electrostatic force of attraction between oppositely charged ions. Electronegativity is the relative attraction of an atom for the shared pair of electrons in a covalent bond. 1ˢᵗ Ionization Energy of an element is the minimum amount of energy required to remove the most loosely bound electron from 1 mole of gaseous atoms in their ground state. 2ⁿᵈ Ionization Energy of an element is the minimum amount of energy required to remove the most loosely bound electron from each singly charged positive ion in a mole of these ions. Atomic Radius of an element is found by taking half the distance between the nuclei of two atoms of the element joined together by a single covalent bond. Dipole-dipole Interactions are the attractive forces between permanent dipoles on two polar molecules. Hydrogen Bonding is a special, stronger type of dipole – dipole interaction, which occurs when hydrogen is bonded to small, highly electronegative elements such as O, N, or F. Van der Waals Forces are weak attractive forces between molecules resulting from the formation of temporary dipoles. Oxidation is the loss of electrons in a reaction. Remember OIL - oxidation is loss Oxidizing Agent is a substance that allows oxidation to happen by gaining electrons itself. Reducing agent is a substance that allows reduction by losing electrons itself. Reduction is the gain of electrons in a reaction. Remember RIG - reduction is gain Active electrodes do react with the electrolyte. Electrode a conductor connected to the positive or negative end of a battery. Electrolysis is the breaking up of a substance due to an electric current passing through it in aqueous solution or when molten. Electrolyte a substance that conducts electricity when dissolved in water or when molten. Electroplating involves coating one inexpensive metal with another more expensive metal. Inert electrodes do not react with the electrolyte. The Electrochemical Series is a table showing metals arranged in order of how easy it is for them to lose electrons Oxidation is an increase in oxidation number. Oxidation Number is the charge that an atom appears to have when the electrons are distributed according to certain rules. Reduction is a decrease in oxidation number. Boyle’s Law at constant temperature, the volume of a fixed mass of any gas is inversely proportional to the pressure of the gas. Charles’ Law at constant pressure, the volume of a given mass of any gas is directly proportional to the Kelvin temperature. Diffusion is the spontaneous spreading out of a substance due to the natural movement of the particles of that substance. Gay-Lussac’s Law the volumes of the gases reacting and the volume of the gaseous products bear a simple whole number ratio to each other, all volumes being measured under the same conditions of temperature and pressure Ideal Gas is a gas that obeys all the assumptions of the kinetic theory under all conditions of temperature & pressure. Volatile Liquid is one that evaporates easily (it has a low boiling point). Empirical Formula of a compound indicates what elements are present in the compound & the simplest whole number ratio in which the atoms of these elements are present. Molecular Formula of a compound indicates the actual number of atoms of each element present in a molecule of a compound. Structural Formula of a compound indicates the arrangement of the atoms within a molecule of the compound. Structural Isomers are compounds with the same molecular formula but different structural formulas. Chloro-alkanes are alkanes where at least 1 hydrogen atom has been replaced by a chlorine atom. Homologous Series is a family of organic compounds with the same general formula, similar chemical properties, & successive members differing by CH₂ Hydrocarbons are compounds consisting of hydrogen and carbon only, bonded together covalently. Primary Alcohol the carbon attached to the OH group is attached to only one other carbon. Secondary Alcohol the carbon attached to the OH group is attached to two other carbons. Tertiary Alcohol the carbon attached to the OH group is attached to three other carbons. Auto-ignition Auto-ignition is ignition before the spark is produced. Bond Energy is the amount of energy in kJ needed to break one mole of bonds of the same type, all species being in the gaseous state. Endothermic Reaction is a reaction in which heat is taken in. Exothermic Reaction is a reaction in which heat is given out. Heat of Combustion of a substance is the heat change in kilojoules when one mole of the substance is completely burned in excess oxygen. Heat of Formation is the heat change in kilojoules when one mole of a substance is formed from its elements in their standard states. Heat of Reaction (∆H) a chemical reaction is the heat in kilojoules released or absorbed when the number of moles of reactants indicated in the balanced equation describing the reaction, react completely. Hess’s Law the heat change of a reaction depends only on the initial & final states of a reaction and is independent of the route by which the reaction may occur. Law of Conservation of Energy energy cannot be created or destroyed, but can change from one form to another. Octane Number is a measure of the tendency of a fuel to resist auto-ignition. Hydrolysis is the chemical decomposition of a substance by water, with water itself also being decomposed. Chemical Equilibrium is a state of dynamic balance in which the rate of the forward reaction equals the rate of the reverse reaction. Le Chatelier’s Principle when a system at equilibrium is subjected to a stress, the system shifts in such a way as to minimize the effect of the stress. Reversible Reaction is a reaction that can take place in either direction. Dissociation Constant of Water Kᵥᵥ = [H₃O⁺] x [OH⁻] = 1 x 10⁻¹⁴ pH of a Solution is defined by pH = - log₁₀ [H₃O⁺]. In words, it is the negative logarithm of the concentration of hydrogen ions in the solution. Flocculation is the coming together of small suspended solids in water. Hard Water is water that will not easily form a lather with soap. Permanent Hardness must be removed by methods other than just boiling. Soft Water easily forms a lather with soap. Temporary Hardness is hardness that can be removed by boiling. Biochemical Oxygen Demand (BOD) is defined as the amount of dissolved oxygen in ppm consumed by biological action, when the sample is kept at 20°C, in the dark, over a period of 5 days.