Ms. Claudia Barahona September, 2, 2011. Elements and symbols (Biosensors) The periodic table (History, periods, groups) Metals, Nonmetals and metalloids.

Chemistry Unit II

Representative elementsTransitionMetalsUnit IIElements and symbols (Biosensors)The periodic table (History, periods, groups)Metals, Nonmetals and metalloidsClassification of groups (alkali metals, alkaline earth metals, transition metals, halogens, noble gases, etc)Ions (Cations and Anions)Naming Ions

MetalsShiny 'metallic' appearanceSolids at room T (except mercury)High melting pointsHigh densitiesMalleable (bend or hammered)Ductile (can be stretched into a wire)Good heat and electrical conductors.

Assigning group numbersRepresentative elements:IA 8ATransition elements:B block

The group number, indicates the number of valence electrons .A newer numbering system assigns group numbers of 1 ---- 18.Valence electronse- in the atoms outermost orbitals (highest principal energy level) - In charge of determining the chemical properties of elements.

HomeworkCharacterization of the elementsLearning guide Pg 28 activity II.1. Part 1, 2 and 3NonmetalsPoor conductors of heat and electricityBrittle solidsLack of lusterLow melting pointsLow densities

Metalloids or semimetalsPossess some characteristics of metals/some of nonmetalsReactivity depends on properties of other elements in reactionOften make good semiconductors

Classification of compoundsBy the number of elementsBinaryTernaryPolyatomic By their chemical functionAcidsBasesOxidesSaltsH.WTo hand in, build a concept map on the different classification of compounds, exaplain each. Give 3 examples.Elements in the periodic tableChemical symbolsONLY THE FIRST LETTER IS CAPITALIZED, if, the symbol has a second letter it is lowercase. Co CORussian chemist, Dmitri Mendeleev, arranged the 60 elements known at that time into groups with similar properties and placed them in order of increasing atomic masses.* The periodic table is arranged in order of increasing atomic number!!!KEY WORDSAtomic mass or atomic weight: Weight average mass of all the natural occuring isotopes of an elementAtomic number: Is equal to the number of protons in an atom.

The periodic tablePeriod: Each horizontal row.

Group/family: Each vertical column, this elements will have similar properties.

Representative elementsTransitionMetalsHomeworkResearch the name of the different groups in the periodic table and the characteristics belonging to each group.Elements in their natural stateMost of the elements in their natural state are found as compounds.

Diatomic molecules7 elements are found as diatomic molecules:H2, N2, O2, F2, Cl2, Br2 and I2

Elements and compounds in natureH.WLearning Guide, Activity I.1, Pg 27Part 1 and 2.

Distribution of the elements in nature

UniversePlanet19Distribution of the elements in nature

Human bodyNomenclature, writing ions symbols and chemical formulas.Ions

IonsOctet rule: Tendency for atoms to attain a noble gas electron configuration.Compounds are the result of the formation of chemical bonds between 2 or more different elements,Ionic Bonds: Metal atoms lose valence e- and atoms of nonmetals gain valence e-.

23Naming IonsForms when atoms lose or gain e- to form octets.CationsA metal ion is named by its element name. ExampleMagnesium Ion Mg2+Sodium Ion Na+

Naming IonsAnionsNegatively charge Ions.Is named by using the first syllable of its name followed by -ide.ExamplesChloride Cl-Bromide Br-

Ionic charges from group numbersGroup IA Alkali metalsIons +1Group IIA Alkaline earth metalsIons +2Group IIIA Ions +3

Ionic charges from group numbersNonmetalsGroup VAIons -3Group VIAIons -2Group VIIA HalogensIons -1

Metals with variable chargesTransition metals: Form 2 or more kinds of positive ions (variable charge) because they lose their outer e- as well as e- from a lower energy level.Is not possible to predict the ionic charge from the group number.ElementPositive IonsName of IonCobaltCo+2Cobalt (II)Co+3Cobalt (III)LeadPb+2Lead (II)Pb+4Lead (IV)The old system of naming ions, involves latin names.The ion with the lesser charge ends with ousThe one with greater charges ends with ic Metals with variable charges

Metals with variable chargesStock systemUse the roman numeral system.The ionic charge is placed in () inmediately after the elemental name of the metal.

Example:Fe +2 Iron (II)Fe+3 Iron (III)

Excercise #1K+F-Na+ O22-Al3+S2-Ga3+ PO43- NH4+ Cu2+ Fe2+ Pb2+SO42- Pb4+ NO3- Sn4+ Pb+4Sn+2N-3Au+1Au+3Octet rule and IonsCovalent Bonds: Forms when atoms of nonmetals share valence e-.

In the formation of either and Ionic bond or a covalent bond, atoms lose, gain or share valence e-

34Activiy II.1Learning Guide, Pg 31Part 1, 2, 3 and 4

Classwork.Learning Guide Activity II.1 Pg 31Part 4Assesment 7.3 Pg 224 Text Book.Activity III.2Classification and identification of inorganic compounds from chemical formulasLearning guide, activity III.2 Pg 33 Part 1,2, 4 Writing names of chemical formulasActivity III.3 Wrinting names from chemical formulasPg 34Part 1, 2, 3, and 5.Ionic compoundsConsist of positive and negative ions.Ions are held together by strong electrical attractions between the opposite charges called ionic bonds.

Charge balance in ionic compoundsFormula: Indicates number and kinds of ions that make up the ionic compound.The sum of the ionic charges in the formula is ALWAYS zero.

Steps for writing a formulaBinary compoundsThose containing only 2 elements.Identify the cation and anion.Balance the charge.Write the formula, cation first, using the subscript from the charge balance.Subscripts in formulasThe subscripts in the formula represent the number of positive and negative ions that give an overall charge of zero.

Writing Ionic formulasIonic compoundsCation is written first, followed by the anion.

Example

Na + and S-2Naming Ionic compoundsIonic compoundsMetal is given first, followed by the nonmetal.Subscripts are never mention.

Mg3N2ExcerciseFormulaCationAnionNameNaClFeCl2Fe2O3Cu3PCuBr2SnCl2PbS2Al2O3NameCationAnionFormulaCopper (I) Oxide Magnesium chlorideNickel (III) OxideTin (IV) ChlorideCobalt (III) chlorideCalcium NitrideZinc bromideGold (I) OxideExcerciseClassification and identification of inorganic compoundscompoundsAcidsBasesOxidesSaltsBinaryTernaryTernaryMetallicNonmetallicBinaryTernaryWriting names from chemical formulasBinary compoundsAcidsNames of acids, usually ends in acid, and their formmulas fot one of two general patterns:Binary acids: Named writing hydro followed by the root of the name of the halogen, then ic and finally acid.Ex. HCl hydrochloric acid

ClassworkIntegrative activity III.4Learning Guide pg 35Part 1 and 2