Chapter 2 Atoms, Molecules, and Ions

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Who proposed the atomic theory?
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John Dalton
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Who laid the experimental foundation of modern chemistry?
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Antoine Lavoisier
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What do Dalton’s atomic theory explain?
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Atom, element, compound, and chemical reaction
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Atomic symbol
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one- or two-letter notation used to represent an atom corresponding to a particular element
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law of multiple proportions
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(Dalton) When two elements form more than one compound, the masses of one element in these compounds for a fixed mass of the other element are in ratios of small whole numbers
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nucleus
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atom’s central core that is positively charged and contains most of the atom’s mass
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electron
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a very light, negatively charged particle and exists in the region around the atom’s positively charged nucleus
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cathode
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negative electrode
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anode
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the positive electrode
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what is the unit of electric charge that is abbreviated C
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coulomb
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What was Rutherford’s contribution to chemistry?
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He discovered the nuclear model of the atom and found that most of the mass of the atom (99.95% or more) is concentrated in the nucleus, around which electrons move
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proton
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nuclear particle having a positive charge equal to that of the electron
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atomic number
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abbreviated (Z); the number of protons in the nucleus of an atom
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element
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a substance whose atoms all have the same atomic number
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neutron
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nuclear particle having a mass almost identical to that of the proton
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mass number
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abbreviated (A); total number of protons and neutrons in a nucleus
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nuclide
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an atom characterized by a definite atomic number and mass number
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isotopes
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atoms whose nuclei have the same atomic number but different mass number; same number of protons, but different numbers of neutrons
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Why are most atomic decimals on the periodic table expressed in decimals?
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They’re the average atomic masses of the isotopes of that element
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mass spectrometer measures…
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atomic masses
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atomic mass unit (amu)
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mass unit equal to one-twelfth the mass of a carbon-12 atom
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atomic weight
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average atomic mass for the naturally occurring element expressed in atomic mass units
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fractional abundance of an isotope
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the fraction of the total number of atoms that is composed of a particular isotope
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periodic table
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a systematic arrangement of elements in rows and columns, highlighting the regular repetition of properties of the elements
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period
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elements in one horizontal row of the periodic table
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group
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elements in any one column of the periodic table
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Group IA of the period table is called…
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alkali metals, soft metals and that react easily with water
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Group VIIA of the periodic table is called…
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halogens
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metal
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substance or mixture that is a good conductor of heat and electricity (except for mercury)
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nonmetal
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element that does not exhibit the characteristics of a metal; most nonmetals are gases (bromine is the only liquid nonmetal)
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metalloid (semimetal)
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element having both metallic and nonmetallic properties; semiconductors
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chemical formula
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notation that uses atomic symbols with numerical subscripts to convey the relative proportions of atoms of the different elements in the substance (ex. H2O)
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molecule
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a definite group of atoms that are chemically bonded together
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molecular formula
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gives exact number of different atoms of an element in a molecule
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polymers
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very large molecules that are made up of smaller molecules repeatedly linked together
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monomers
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small molecules that are linked together to form polymers
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ion
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an electrically charged particle
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anion
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negatively charged ion
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cation
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positively charged ion
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organic compounds
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molecular substances that contain carbon
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hydrocarbons
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compounds with hydrogen and carbon
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functional group i
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s a reactive portion of a molecule that undergoes predictable reactions
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functional group -OH
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alcohol
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functional group -O-
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ether
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functional group -COOH
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carboxylic acid
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chemical nomenclature
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systematic naming of chemical compounds
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inorganic compounds
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composed of elements other than carbon
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oxoanions
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ion that consists of oxygen and another element (can be recognized by suffix -ate or -ite)
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binary compounds
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a compounds composed of only two elements
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oxoacid
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an acid containing hydrogen, oxygen, and another element
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hydrate
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a compounds that contains water molecules weakly bound in its crystals
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chemical equation
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symbolic representation of a chemical reaction in terms of chemical formulas
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reactant
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starting substance in a chemical reaction
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product
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substance that results from a reaction
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molecular weight (MW)
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sum of the atomic weights of all the atoms in a molecule of the substance
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formula weight (FW)
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sum of the atomic weights of all atoms in a formula unit
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mole
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quantity of a given substance that contains as many molecules or formula units of atoms in 12g of carbon-12
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Avogadro’s number
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number of atoms in 12g of carbon-12 (6.02×10^23)
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molar mass
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the mass of one mole of a substance
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stoichiometry
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the calculation of the quantities of reactants and products involved in a chemical reaction
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limiting reactant
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the reactant that is entirely consumed when a reaction goes to completion
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theoretical yield
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maximum amount of a product that can be obtained by a reaction from a given amounts of reactants

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