quantitative chem (3)

• Avogadro's constant


  the number of atoms, molecules, or ions in a mole of any substance (i.e., 6.02 × 10-23 per mol)
• burette


  a long glass tube with a tap at one end and markings to show volumes of liquid
• concentration


  the amount of a substance dissolved in a given volume of liquid
• concordant


  when you have two titration results that are within 0.1cm3 of each other. These precise results can then be used to calculate an
• limiting reactant


  the reactant in a chemical reaction that when used up causes the reaction to stop
• mole


  the amount of substance in the relative atomic or formula mass of a substance in grams
• percentage yield


  the actual mass of product collected in a reaction divided by the maximum mass that could have been formed in theory, multiplied by 100
• pipette


  a glass tube used to measure accurate volumes of liquids
• relative atomic mass Ar

  the average mass of the atoms of an element compared with carbon-12 (which is given a mass of exactly 12). The average mass must take into account the proportions of the naturally occurring isotopes of the element
• relative formula mass Mr

  the total of the relative atomic masses, added up in the ratio shown in the chemical formula, of a substance
• titration


  a method for measuring the volumes of two solutions that react together
• yield


  the mass of product that a chemical reaction produces
• aqueous solution


  the mixture made by adding a soluble substance to water
• atom


  the smallest part of an element that can still be recognised as that element
• atomic number


  the number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number
• balanced symbol equation


  a symbol equation in which there are equal numbers of each type of atom on either side of the equation
• biofuel


  fuel made from animal or plant products
• chromatography


  the process whereby small amounts of dissolved substances are separated by running a solvent
• along a material such as absorbent paper
• compound


  a substance made when two or more elements are chemically bonded together
• electron


  a tiny particle with a negative charge. Electrons orbit the nucleus of atoms or ions in shells
• electronic structure


  a set of numbers to show the arrangement of electrons in their shells (or energy levels)
• element


  a substance made up of only one type of atom. An element cannot be broken down chemically into any
• simpler substance
• group


  all the elements in the columns (labelled 1 to 7 and 0) in the periodic table
• ion


  a charged particle produced by the loss or gain of electrons
• isotope


  atoms that have the same number of protons but different number of neutrons, i.e., they have the same atomic number but different mass numbers
• law of conservation of mass


  the total mass of the products formed in a reaction is equal to the total mass of the reactants
• mass number


  the number of protons plus neutrons in the nucleus of an atom
• neutron


  a dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge
• noble gases


  the very unreactive gases found in Group 0 of the periodic table. Their atoms have very stable electronic structures
• nucleus (of an atom)


  the very small and dense central part of an atom that contains protons and neutrons
• periodic table


  an arrangement of elements in the order of their atomic numbers, forming groups and periods
• product


  a substance made as a result of a chemical reaction
• proton


  a tiny positive particle found inside the nucleus of an atom
• reactant


  a substance we start with before a chemical reaction takes place
• shell


  an area in an atom, around its nucleus, where electrons are found
• state symbol


  the abbreviations used in balanced symbol equations to show if reactants and products are solid (s), liquid (l), gas (g) or dissolved in water (aq)
• symbol equation


  an equation that helps you see how much of each substance is involved in a chemical reaction by showing the chemical symbols and formulae of all the reactants and products involved
• word equation


  a way of describing what happens in a chemical reaction by showing the names of all reactants and the products they form