Chemistry - an illustrated guide to science (794128), страница 36
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Theelements beryllium, magnesium, calcium, strontium, barium,and radium. These elements have two electrons in their outershell.group 3 elements The elements boron, aluminum,gallium, indium, and thallium. These elements have a full sorbital and one electron in a p orbital in their outer shell.group 4 elements The elements carbon, silicon,germanium, tin, and lead. These elements have a full s orbitaland two electrons in two p orbitals in their outer shell.group 5 elements The elements nitrogen, phosphorus,arsenic, antimony, and bismuth.
These elements have a full sorbital and three electrons in three p orbitals in their outershell.group 6 elements The chalcogens. The elements oxygen,sulfur, selenium, tellurium, and polonium. These elementshave a full s orbital, one full p orbital, and two half-full porbitals in their outer shell.group 7 elements The halogens. The elements fluorine,chlorine, bromine, iodine, and astatine. These elements havea full s orbital, two full p orbitals, and one half-full p orbital intheir outer shell.group 8 elements.
The noble or inert gases. The elementshelium, neon, argon, krypton, xenon, and radon. The outershell of the atoms in these elements is complete, renderingthese elements unreactive.half-life The time required for half the atoms of aradioactive substance to disintegrate.halide A compound that a halogen makes with anotherelement.
Metal halides are ionic; non-metal halides areformed by covalent bonding.halogens See Group 7 elements.helium (He) A colorless, odorless gaseous element that isthe second most abundant element on Earth.hexagonal close packing In crystalline structures, a wayof packing atoms so that alternating layers overlie oneanother in an ABABAB pattern.hexose A monosaccharide with six carbon atoms.homologous series A series of related organiccompounds. The formula of each member differs from thepreceding member by the addition of a –CH2– group.hydration The combination of water and another substanceto produce a single product.hydride A compound formed between hydrogen andanother element.hydrocarbon An organic molecule consisting only ofcarbon and hydrogen.hydrochloric acid (HCl) A colorless fuming solution ofhydrogen chloride.hydrogen (H) An odorless, easily flammable gaseouselement that is the most abundant on Earth.hydrogen bond A weak bond between hydrogen andanother element with partial but opposite electrical charges.hydrogen chloride (HCl) A colorless gas with a pungentsmell that fumes in moist air.
It is very soluble in water.hydrogen peroxide (H2 O2 ) A colorless or pale blueviscous liquid. It is a strong oxidizing agent, but it can also actas a reducing agent.hydrogen sulfide (H2 S) A colorless, poisonous gassmelling of bad eggs that is moderately soluble in water. It isa reducing agent.hydronium ion The positive ion (H3O) + . It is the hydratedform of the hydrogen ion (H+ ) or proton.hydrophilic Water-loving. In solution, it refers to a chemicalor part of a chemical that is highly attracted to water.hydrophobic Water-hating.
It refers to a chemical or part ofa chemical that repels water.hydroxide A compound containing the hydroxide ion or thehydroxyl group bonded to a metal atom.hydroxide ion The negative ion (OH–) present in alkalis.immiscible Incapable of mixing.indicator A substance that indicates by a change in its colorthe degree of acidity or alkalinity of a solution or thepresence of a given substance.inert A substance that is either very or completelyunreactive.inert gases See noble gases.infrared Electromagnetic radiation with a greaterwavelength than the red end of the visible spectrum.insoluble A substance that does not dissolve in a particularsolvent under certain conditions of temperature andpressure.iodine (I) A grayish-black non-metallic element that isessential in the diet and is used in disinfectants andphotography.ion An electrically charged atom or group of atoms.ionic bonding A type of bonding that occurs when atomsform ions and electrons are transferred from one atom toanother.ionic compound Compounds consisting of ions heldtogether by strong ionic bonds.
Ionic compounds areelectrolytes.© Diagram Visual Information Ltd.gas-liquid chromatography A type of chromatography20 2© Diagram Visual Information Ltd.KEY WORDSionic crystal A type of crystal where ions of two of moreelements form a regular three-dimensional arrangement(crystal structure).ionization energy The energy needed to removecompletely an electron from a neutral gaseous atom or ionagainst the attraction of the nucleus.ionizing radiation Any radiation capable of displacingelectrons from atoms or molecules and so producing ionsiron (Fe) A silvery, malleable and ductile metallic elementused in construction.irradiation The use of radiation to destroy microorganismsin foods.isomer One of two or more (usually organic) compoundshaving the same molecular formula and relative molecularmass but different three-dimensional structures.isomerism The rearrangement atoms in a molecule tomake it more efficient.isomerization The transformation of a molecule into adifferent isomer.isotope Atoms of the same element (all chemically identical)having the same atomic number but containing differentnumbers of neutrons, giving a different mass number.ketone An organic compound that contain two organicradicals connected to a carbonyl group.kinetic energy The energy a body has by virtue of itsmotion.lanthanide series A series of metallic elements with theatomic numbers 57 to 71.
The metals are shiny and areattacked by water and acids.lattice The orderly three-dimensional arrangements ofatoms, molecules, or ions seen in crystals.lead (Pb) A silvery-white metallic element used in batteriesand in water, noise, and radiation shielding.lead sulfide (PbS) A brownish-black insoluble crystal. Itoccurs naturally as the mineral galena.Le Chatelier’s principle If a chemical reaction is atequilibrium and a change is made to any of the conditions,further reaction will take place to counteract the changes inorder to re-establish equilibrium.limewater A solution of calcium hydroxide that is used totest for the presence of carbon dioxide.limiting form The possibilities for the distribution ofelectrons in a molecule or ion.liquid A state of matter between solid and gas.
Particles areloosely bonded, so can move relatively freely.lone pair A pair of electrons in the outermost shell of anatom that are not involved in the formation of covalentbonds.luminescence Light emission from a substance caused byan effect other than heat.magnesium (Mg) A silvery-white metallic element used inalloys and castings.magnesium oxide (MgO) A white solid used forreflective coatings and as a component of semiconductors.manganese (Mn) A soft, gray metallic element used inmaking steel alloys.mantle The layer of Earth between the crust and the core.mass The measure of a body’s resistance to acceleration.mass number The total number of protons and neutronsin the nucleus of an atom.mass spectrometry A technique for determining thecomposition of molecules by using the mass of their basicconstituentsmelting point The point at which a substance changesstate from solid to liquid.methane (CH4 ) The simplest alkane.
A colorless, tasteless,odorless flammable gas used as a fuel.mineral A natural inorganic substance with distinct chemicalcomposition and internal structure.mixture A system consisting of two or more substances thatare not chemically combined.mobile phase The phase that moves along the stationaryphase. It is the solvent in paper chromatography.molarity The concentration of solution giving the numberof moles of solute dissolved in 1 kg of solvent.mole The amount of a substance that contains the samenumber of entities (atoms, molecules, ions, etc.) as there areatoms in 12 g of the carbon-12 isotope.molecular mass The sum of the atomic masses of allatoms in a molecule.
The mass of a mole of the substance.molecule The smallest part of an element or chemicalcompound that can exist independently with all theproperties of the element or compound.monomer A basic unit from which a polymer is made.monosaccharide A simple sugar such as glucose.nanotube An isotope of carbon consisting of long thincylinders closed at either end with caps containingpentagonal rings.neptunium (Np) A radioactive metallic element that can besynthesized by bombarding U-238 with neutrons.neptunium series A radioactive series composed ofartificial isotopes.neutral A solution whose pH is 7.neutralization The reaction of an acid and a base forming asalt and water..neutron One of the two major components of the atomicnucleus.
It has no electric charge.neutron star The smallest but densest kind of star,apparently resulting from a supernova explosion.nickel (Ni) A hard, malleable and ductile, silvery-whitemetallic element that is a component of Earth’s core.nitrate A salt of nitric acid.nitric acid (HNO3) A colorless, corrosive, poisonous,fuming liquid that is a strong oxidizing agent.nitrite A salt of nitrous acid.nitrogen (N) A colorless gaseous element essential for thegrowth of plants and animals.nitrogen cycle The process by which nitrogen is recycledin the ecosystem.noble gases Group 8 elements: helium, neon, argon,krypton, xenon, and radon. These gases do not combinechemically with other materials.nucleon A proton or neutron.nucleus The positively charged core of an atom thatcontains almost all its mass.nuclide A particular isotope of an element, identified by thenumber of protons and neutrons in the nucleus.optical isomerism A form of isomerism in which twoisomers are the same in every way except that they are mirrorimages that cannot be superimposed on each other.20 3orbital An area around an atom or molecule where there is ahigh probability of finding an electron.ore A mineral from which a metal or non-metal may beprofitably extracted.oxidation The process by which a substance gains oxygen,loses hydrogen, or loses electrons.oxidation state The sum of negative and positive chargesin an atom.oxide A compound consisting only of oxygen and anotherelement.
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