Chapter 6.1 Slides

6.1 Organizing the Elements Chapter 6The Periodic Table6.1 Organizing the Elements6.2 Classifying the Elements6.3 Periodic Trends1Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements CHEMISTRY& YOUHow can you organize and classifyelements?If you have ever played a cardgame, then you have probablyorganized your cards. Maybe youclassified them by color or number.2Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Searching for anOrganizing PrincipleSearching for an Organizing PrincipleHow did chemists begin to organize the known elements?3Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Searching for anOrganizing PrincipleA few elements, including copper,silver, and gold, have been known forthousands of years. There were only 13 elements identified by theyear 1700.– Chemists suspected that other elements existed.– As chemists began to use scientific methods tosearch for elements, the rate of discovery increased.– In one decade (1765–1775), chemists discovered fivenew elements.4Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Searching for anOrganizing PrincipleEarly chemists used the properties ofelements to sort them into groups. In 1829, a German chemist, J. W. Dobereiner, published a classificationsystem. In his system, the known elements were grouped into triads. A triad is a set of three elements with similar properties.– The elements shown here formed onetriad. Chlorine, bromine, and iodinemay look different, but they have verysimilar chemical properties.5Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Searching for anOrganizing PrincipleDobereiner noted a pattern in his triads.One element in each triad tended to haveproperties with values that fell midwaybetween those of the other two elements. For example, the average of the atomicmasses of chlorine and iodine is [(35.453 126.90)/2], or 81.18 amu. This value is close to the atomic mass ofbromine, which is 79.904 amu.6Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Why was it important forscientists to find a logical way toorganize the elements?7Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Why was it important forscientists to find a logical way toorganize the elements?Finding a logical way to organizethe elements made it possible forscientists to determine how manyelements they were looking for.8Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Mendeleev’s PeriodicTable6.1 Organizing the Elements Mendeleev’s Periodic TableHow did Mendeleev organize his periodic table?9Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Mendeleev’s PeriodicTableIn 1869, a Russian chemist and teacher, Dmitri Mendeleev, published a tableof the elements.10 He wrote the properties of eachelement on a separate note card. This approach allowed him to movethe cards around until he found anorganization that worked.Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Mendeleev’s PeriodicTableThe organization he chose was a periodictable. Elements in a periodic table are arrangedinto groups based on a set of repeatingproperties. Mendeleev arranged the elements in his periodic table in order ofincreasing atomic mass.11Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Why was Mendeleev’s periodic tablean improvement over Dobereiner’striad classification system and otherearlier systems?12Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Why was Mendeleev’s periodic tablean improvement over Dobereiner’striad classification system and otherearlier systems?Mendeleev’s periodic table couldencompass all known elements andaccurately predicted the existence andproperties of undiscovered elements.13Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Today’s Periodic TableToday’s Periodic TableHow is the modern periodic table organized?14Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Today’s Periodic TableIn a periodic table based on atomic mass, iodine should come beforetellurium since iodine has a smaller atomic mass than tellurium does. However, based on its chemical properties,iodine belongs in a group with bromine andchlorine.15Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Today’s Periodic TableMendeleev placed tellurium before iodine in his periodic table. He assumed that the atomic masses for iodineand tellurium were incorrect, but they werenot. The problem wasn’t with the atomic massesbut with using atomic mass to organize theperiodic table.16Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Today’s Periodic TableMendeleev developed his table before scientists knew about the structure ofatoms. He didn’t know that the atoms of eachelement contain a unique number ofprotons. Recall that the number of protons is theatomic number.17Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Today’s Periodic TableIn the modern periodic table,elements are arranged in order ofincreasing atomic number.123456718Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Today’s Periodic TableThe elements are arranged in order ofatomic number, starting with hydrogen,which has atomic number 1.123456719Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Today’s Periodic TableThere are seven rows, or periods, in the table. Each period corresponds to a principal energy level.123456720Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Today’s Periodic TableThere are seven rows, or periods, in the table. There are more elements in higher-numbered periods because thereare more orbitals in higher energy levels.123456721Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Today’s Periodic TableThe properties of the elements within aperiod change as you move across a periodfrom left to right. The pattern of properties within a periodrepeats as you move from one period to thenext. This pattern gives rise to the periodic law:When elements are arranged in order ofincreasing atomic number, there is a periodicrepetition of their physical and chemicalproperties.22Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Are elements with similar propertiesfound in the rows (periods) orcolumns (groups) of the modernperiodic table?23Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Are elements with similar propertiesfound in the rows (periods) orcolumns (groups) of the modernperiodic table?Elements with similar properties arefound in the columns, or groups, of themodern periodic table.24Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsMetals, Nonmetals, and MetalloidsWhat are the three broad classes of elements?25Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsPeriodic tables are sometimes color-coded to classify types of elements.26Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsEach column, or group, in this table hasthree labels. Scientists in the United States primarily usethe labels shown in red. Scientists in Europe use the labels shown inblue.27Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsThe International Union of Pure and AppliedChemistry (IUPAC) is an organization thatsets standards for chemistry.28 In 1985, IUPAC proposed a new system for labeling groups in the periodictable. They numbered the groups from left to right 1 through 18 (the blacklabels).Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsDividing the elements into groups is not theonly way to classify them based on theirproperties. The elements can be grouped into three broad classes based on theirgeneral properties.29Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsThree classes of elements are metals,nonmetals, and metalloids. Across a period, the properties of elementsbecome less metallic and morenonmetallic.30Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Metals, Nonmetals, andMetalloids6.1 Organizing the Elements MetalsThe number of yellow squares in the tableshows that most elements are metals—about 80%.31Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.Metals, Nonmetals, andMetalloids6.1 Organizing the Elements MetalsMetals are generally good conductors ofheat and electric current.32 Copper is second only to silver as aconductor of electric current. The copper used in electrical cablesmust be 99.99 percent pure.Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Metals, Nonmetals, andMetalloids6.1 Organizing the Elements Metals A freshly cleaned or cut surface of ametal will have a high luster, or sheen.The sheen is caused by the metal’sability to reflect light. All metals are solids at roomtemperature, except for mercury (Hg).33Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.Metals, Nonmetals, andMetalloids6.1 Organizing the Elements Metals Many metals are ductile,meaning that they can be drawninto wires. Most metals are malleable,meaning that they can behammered into thin sheetswithout breaking.34Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsNonmetalsBlue is used to identify the nonmetals.35Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsNonmetalsThere is a greater variation in physicalproperties among nonmetals than amongmetals.36 Most nonmetals are gases at room temperature, including the maincomponents of air—nitrogen and oxygen. A few are solids, such as sulfur and phosphorus. One nonmetal, bromine, is a dark-red liquid.Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.

Metals, Nonmetals, andMetalloids6.1 Organizing the Elements NonmetalsThe variation among nonmetals makes it difficultto describe one set of general properties that willapply to all nonmetals. A diamond, which is composed ofcarbon, is very hard.37 Some match heads are coated withphosphorus, a brittle solid.Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.6.1 Organizing the Elements Metals, Nonmetals, andMetalloidsNonmetalsNonmetals tend to have properties thatare opposite to those of metals.38 In general, nonmetals are poor conductors of heat and electric current.Carbon, in the form of graphite, is an exception to this rule. Solid nonmetals tend to be brittle, meaning that they will shatter if hitwith a hammer.Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved.