UNIT 4 WRITING & NAMING CHEMICAL COMPOUNDS

Transcription

1 UNIT 4 WRITING & NAMING CHEMICAL COMPOUNDS

2 What is the Periodic Table? Periodic Trends Metals and Nonmetals What is the Oxidation number? More on Ionic Compounds Binary Naming of Ionic Compounds Polyatomic Ions Molecular Compounds Little bit of Organic Chemistry (Hydrocarbons) Diatomic's

3 PERIODIC TABLE Organization of elements in increasing atomic number/number of protons from left to right and from top to bottom The horizontal rows are called periods Vertical rows are called columns or families Three types of elements: Metals, Nonmetals, & Metaloids

4 METALS AND NONMETALS There are many more metals then nonmetals Metaloids make up the Stairs

5 METALS CHARACTERISTICS Have luster (shiny) Can conduct electricity this is means that they are conductors Ductile- can be pulled out into a wire Malleable- can be hammered into thing sheets Always lose electrons from their Valance energy level to form positive Ions or Cations The Roman numeral or numbers with an A beside them at the top of the column on the periodic table are the number of electrons in the Valence electrons each element in the column has

6 NONMETALS Do not have luster and are frequently powdery, liquid or gaseous do not conduct electricity not ductile or malleable Always gains electrons in there Valance energy level until they have 8 of electrons (octet rule) and for negative ions which are called Anions

7 PERIODIC TABLE CONTINUED Each Family group has the same number of electrons and will either gain or lose electrons to have a fully filled valence shell (8 of Valance electrons), a halfway filled valence shell (4 of Valance electrons), or an empty valence shell (0 pairs of Valance electrons). Because of this, names were assigned to each family

8 FAMILY 1: ALKALI METALS These elements have 1 single valance electron These elements what to have an empty valance shell so they tend to loose their electron when binding to nonmetals These elements are the most reactive

9 FAMILY 2: ALKALINE EARTH METALS These elements tend to lose 2 valance Electrons they have an oxidation of +2 making them very reactive FAMILY 3-12: TRANSITION METALS 38 elements. The valence electrons are present in more then one shell this is why they have several oxidation states. FAMILY 17: HALOGENS Nonmetals with 7 valence electrons in its outer shell. Oxidation number of -1 FAMILY18: NOBLE GASES These elements have a full valence shell making them very nonreactive, oxidation number is 0

10 WHICH FAMILY BELONGS TO THE NONMETALS? Alkaline Alkaline Earth Transitions Hallogens

11 WHICH OF THESE ELEMENTS BELONG TO THE ALKALINE EARTH METALS? Li K Ca C Br

12 WHAT FAMILY DOES FLORINE BELONG TO? NOT MULTIPLE CHOICE HALLOGENS

13 WHAT FAMILY (COLUMN) DOES THE NOBLE GASES MAKE UP? NOT MULTIPLE CHOICE

14 PERIODIC TRENDS Reactivity: how easily a metal atom loses its electron (ionization energy). The more reactive the metal the easier it bonds to a nonmetal. The Chart below shows the reactivity trend for Metals. It is the opposite for Nonmetals. Decreases Increases

15 PERIODIC TRENDS Electronegativity- Tendency of an atom to pull electrons which are bonded close to itself and add them to its valance orbit The most electro negative element is Fluorine Increases Decreases

16 PERIODIC TRENDS Electron Affinity- Amount of energy absorbed or given off when an atom is forced to accept an electron The more negative value the higher the affinity and vise versa Increase Decreases

17 PERIODIC TRENDS Ionization Energy- Amount of energy to remove 1 electron from an atom Increases Decreases

18 PERIODIC TRENDS Atomic Radius- radius across an atom Decreases Increases

19 PERIODIC TRENDS Shielding- a barrier made of inner-shell electrons which serves to decrease the pull of the nucleus on outer electrons Constant Increases

20 WHAT IS THE MOST ELECTRONEGATIVE ELEMENT?

21 WHICH ELEMENT HAS THE HIGHEST ELECTRON AFFINITY Li C O Fr

22 WHICH METAL IS MOST REACTIVE? Rb Li Al O Ca

23 WHICH ELEMENT HAS THE LEAST AMOUNT OF SHIELDING? K Te C He N

24 WHICH NONMETAL IS THE MOST ELECTRONEGATIVE? C P Ca Na At

25 WHAT IS THE MOST REACTIVE NONMETAL Cl Ga Se I At

26 WHICH ELEMENT HAS THE HIGHER IONIZATION ENERGY? N P As Sb Bi

27 Positive Ions ace called Cations. They have more protons then they have electrons. Metals always lose electrons. Negative ions are called Anions. They have gained more electrons in their valance energy level and therefore have more electrons then protons.

28 OXIDATION NUMBERS Oxidation Number- The overall charge on an ion after It has lost electrons (metals) or gained electrons (nonmetals) It is easier to memorize the family trends for the oxidation numbers The oxidation number of an atom in a compound is the charge it would have if all shared electrons were assigned to that with the greatest attraction for electrons.

29 OXIDATION # TRENDS

30 RULES FOR ASSIGNING OXIDATION NUMBERS Oxidation number of an atom in its free Cu Oxidation number is 0 element for is 0 The oxidation stat of a monoatomic ion is equal to its charge Ca2+ 2+ ox # H2O The sum of oxidation numbers in a neutral H ox# 1+ molecule is 0 and an Ion is equal to the O ox# 2- stated charge (so we needed 2 H to count for O s charge) Group 1 always have an oxidation number of 1+ Group 2 have a 2+ ect. NaCl Na ox# 1+ Cl ox# 1-

31 COMPOUNDS WITH OXIDATION NUMBERS When ions (charged elements) are combined together forming compounds, the overall charge of the compound which results must be neutral or 0 In order to do this sometimes you might need to change the ratio of elements in the compound 2+ 1Mg Cl MgCl2

32 WEIGHTING CHEMICAL FORMULAS Split the ions up into its components Assign Oxidation numbers to each individual element Cross your oxidation numbers and make note of ration Check if it zero s out Wright compound formula Wright the metal ion FIRST and the nonmetal LAST

33 WRIGHT THE CORRECT FORMULA FOR THE A COMPOUND BETWEEN THESE TWO ELEMENTS: Lithium and Florine Calcium and Sulfur Cesium (#55) and Oxygen Potassium and Chloride Sodium and Oxygen Calcium and Bromine

34 IONIC COMPOUNDS Ionic compounds- compounds made of A Metal and Nonmetal Metal and Polyatomic Ion Ammonium Ion (NH4) and Nonmetal Ammonium Ion (NH4) and a Polyatomic Ion

35 BINARY NAMING OF IONIC COMPOUNDS Binary Naming is naming of 2 elements only First: call the entire name of the metal Then: shorten the name of the nonmetal and add ide as a suffix KCl Potassium Chloride

36 EXAMPLE OF IDE ENDINGS Fluorine- Fluoride Oxygen- Oxide Sulfur- Sulfide Phosphorus- Phosphide Bromine-Bromide Nitrogen- Nitride Iodine- Iodide Chlorine- Chloride

37 NAME THE FOLLOWING IONIC COMPOUNDS: MgBr2 NaF ZnS Na2O K 3N Al2O3

38 TRANSITION METALS RULES Each transition metal has multiple oxidation numbers When naming these you must use the latin names and the ic and ous naming system Use the ic suffix for the highest oxidation number Use the ous suffix for the lowest oxidation number

39 EXAMPLES Copper (+2 & +1) Cupric and Cuprous Iron (+3 & +4) Ferric and Ferrous Lead (+4 & +2) Plumbic and Plumbous Tin (+4 & +2) Stannic and Stannous Mercury (+2 & +1) Mercuric and Mercurous

40 IUPAC NAMING IUPAC (International Union of Practical and Applied Chemistry) IUPAC came up with a naming system for these transition metals that included metals with more then 2 different charges they called it Stock naming Uses a metal s name followed by a Roman numeral in parentheses which indicates its oxidations number 2+ Cu would be called copper (II)

41 WRITE THE CORRECT FORMULA: Iron (III) Oxide Tin (IV) Chloride Lead (IV) Oxide Tin (II) Sulfide Mercury (II) Bromide Iron (II) iodide

42 HOW DO YOU KNOW WHICH OXIDATION NUMBER TO USE IF YOU ARE GIVEN A FORMULA AND ASKED TO NAME THE COMPOUND? Check your NEGATIVE ION S oxidation number. These never change Once you've figured out the negative oxidation number you make the compound s overall charge neutral unless specified otherwise. Pay attention to your ratios!!!!! FeO Iron (II) Oxide

43 WHAT IF YOUR RATIO IS NOT 1:1 SnS2 Still Check the negative ion first, But keep in mind the ratio (stoichiometry) and multiply the OXIDATION NUMBER by the RATIO. Once you found the new total negative oxidation number then you can find the positive oxidation by making the compound neutral. SnS2 Sulfur -2 oxidation number But there are 2 Sulfur Ions So the new oxidation number -2 x 2 = -4 The overall oxidation is neutral. So in order to make -4 0 the Tin (Sn) +4. Tin (IV) Sulfide

44 NAME THE FOLLOWING COMPOUNDS WITH STOCK NAMING: FeCl2 SnO Hg2I2 CuI PbO2

45 POLYATOMIC IONS Polyatomic Ions- Ions which are imposed of several different elements These elements stay together in a chemical reaction and the entire group has an oxidation number or charge I STRONGLY ADVISE YOU MEMORIZE THESE ASAP!!!! When writing a polyatomic ion in a compound if you have a subscript you must put your Polyatomic Ion in parenthesis then the subscript outside of it. Polyatomic Al(NO3)3 Ion Subscript

46 POLY ATOMIC ION CHART

47 WRITE THE CORRECT FORMULA FOR EACH OF THE FOLLOWING COMPOUNDS: Aluminum Nitrate Copper (II) Sulfate Zinc Chlorate Silver Nitrite Aluminum Permanganate

48 NAMING MOLECULAR COMPOUNDS These compounds are made up of 2 nonmetals When Naming these compounds use a prefix to indicate the number of atoms of each element presents Do not use prefixes in IONIC compounds Outside of Prefixes keep the first metals name the same then add the suffix ide onto the end of shortened second metal Prefixes: No prefix needed or use mono Di Tri Tetra Penta 6. Hexa 7. Hepta 8. Octa 9. Nona 10.Deca

49 NAME THE FOLLOWING MOLECULAR COMPOUNDS: N 2O 5 SO3 CO P4O10 As2O3

50 HYDROCARBONS (A LITTLE ORGANIC CHEMISTRY) Organic Chemistry is basically the chemistry of Carbon Hydrocarbons are Carbon chains with Hydrogens attached to them There are 2 types of Hydrocarbon chains: Straight Chain: Pentane Cyclic Chain: Cyclopentane

51 HYDROCARBONS STRAIGHT CHAINS NAMING CxH2x + 2 General Formula for recognition: Once you've identified it as a straight chain: you count the number of Carbons Use the same prefixes as did in molecular compounds from 5-10 then add the suffix ane on the end For hydrocarbons with 1-4 carbons you will just have to memorize the prefix Carbons Methane 2. Ethane 3. Propane 4. Butane C5H12 Pentane

52 CYCLIC HYDROCARBONS CxH2x Formula for Recognition: The smallest Cyclic structure has 3 Carbons When naming theses structures you count the amount of Carbons and use the same name as the straight chain hydrocarbons EXCEPT: You add the prefix cyclo C6H12 Cyclohexane C8H16 Cyclooctane

53 NAME THE HYDROCARBONS Hint: remember to find out the equation for both straight chain and cyclic hydrocarbons C 3H 6 C5H12 C8H18 C 4H 8 C7H16 C5H10 CxH2x + 2 CxH2x

54 WRITE THE CHEMICAL EQUATION: Hint: remember the equation for both straight chain and cyclic hydrocarbons Cyclohexane Ethane Cyclobutane Decane CxH2x + 2 CxH2x

55 DIATOMIC S There are 7 elements that cannot exist by themselves as single atoms, these are known as the diatomic They occur naturally in the world just in pairs All these elements in their purest forms combine with each other (having a 2 subscript next to them). These elements conveniently make a 7 on the periodic table besides Hydrogen Br2 H2 O2

56 DIATOMICS TRENDS

57 REMEMBER WHEN NAMING COMPOUNDS First What kind of compound is it? Ionic (metal and nonmetal) Molecular (nonmetal and nonmetal) Polyatomic Hydrocarbons Then: Find out the ratio of atoms and/or oxidation number Then: follow rules for each set of compounds

58