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NCSU CH 101 - Naming Finding the Chemical Formula of Ions and

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Lecture 10Outline of Last Lecture I. Electron configuration of ionsII. Oxidation statesA. The Six Rules of OxidationIII. Predicting Oxidation Formulas IV. Possible Oxidation States for Unknown Elements X, Y and ZOutline of Current Lecture I. Types of BondsII. Naming CompoundsIII. Finding the Chemical FormulaIV. Polyatomic IonsA. Oxyanions or (Oxoanions)Current Lecture*Side Note: Last lecture notes I included the statement “To find the electron configuration of ions you take the configuration of the element and either subtracting (in the case of a cation) electrons from the orbitals in this order p, s, d, f, etc.” I would like to amend that by saying that you take out of the p orbital first UNLESS it is filled, if it is filled then you take from the s orbital first.I. Types of Bonds- In CH 101 you are going to be working with ionic, covalent, and metallic bonds. Ionic bonds are between a metal and a non-metal where electrons are transferred from the low electronegative element (metal) to the element with the higher electronegativity (non-metal). This bond occurs when the difference in electronegativity between the two elements is greater than or equal to 1.8. The bond between rubidium and sulfur is ionic.Covalent bonds are between two non-metals that share electrons without creating an ion. This bond occurs when the difference in electronegativity between the two elements is less than or equal to 0.4. The bond between silicon and phosphorus is covalent. CH 101 1st Edition- Polar covalent bonds are created when there is an uneven sharing of electrons, this bond occurs when the difference in electronegativity is greater than 0.4 but less than 1.8. The bond between Carbon and Fluorine is polar covalent.Metallic bonds are between two metals and are held together by the ‘sea of electrons’ that surround and atomUse this chart to calculate the difference in electronegativity or use the periodic table to estimate the type of bond,II. Naming Compounds- You will learn that when naming compounds, you must look at the placement of the element on theperiodic table and the amount of atoms of each element in the compound.Endings: -ide -ite –ateMonoatomic anion/cation – An anion/cation that consist of only one element whereas a polyatomic ion is an ion that consists of more than one element. Monoatomic = O-2, F-1, As-3 Polyatomic = SO42-- With cation molecules (Group 1 and Group two), the compound is just called the element name with the word ‘ion’ after it. K1+ = Potassium ion, Na1+ = Sodium ion, Ra2+ = Radium ion- With compounds that include transition metals you use roman numerals to represent the oxidation state of that transition metal. The ending of the word will be –ide if it’s a monoatomic ion or –ate or–ite depending on the polyatomic ion. NiSO3 = Nickel (II) Sulfite, TiBr3 = Thallium (III) Bromide.There are a few elements near the transition metals who will never use roman numerals because they only have one oxidation state Al3+, Ag1+, Zn2+,and Cd2+.*review how to find the oxidation state of an ionic compound from last lectures notes because a bond between a transition metal and a non-metal is an ionic bond.- ide- Monoatomic anions changes to –ide. N3- = Nitride, S2- = Sulfide, O2- = Oxide- This also occurs when there is an ionic bond (a bond between a metal and a non-metal). The anion in the compound changes its ending to –ide. CO2 = Carbon Oxide, LiBr = Lithium Bromide- Covalent bonds between two non-metals will have the suffix –ide. Also, the nonmetals will take on different prefix depending on how many atoms of that element are in the molecule. Here is a chart of the prefix’s that correspond with the amount of atoms of each element. *note that if the non-metal that comes first when naming the compound is the element that is mostmetal-like which would be furthest to the bottom left of the periodic table, and if the first element only has one atom do not include the prefix mono.Amount of atoms Prefix1 Mono2 Di3 Tri4 Tetra5 Penta6 Hexa7 Hepta8 Octa9 Nona10 DecaExamples of covalent compounds. N2O5 = dinitrogen pentoxide, CO = carbon monoxide, PH3 = phosphorus trihydride.- ate- A compound will end in –ate if the oxidation number of the cation is equal to it’s main group number. Sulfur’s group number is 6, in the polyatomic ion SO42- the oxidation state of Sulfur is +6, and therefore we call this compound sulfate. If you are given a compound with the ending of –ite, when you add one more oxygen to this compound you will get the compound with the ending –ate,Sulfite = SO32- and Sulfate = SO4 2-. If you add another oxygen to any compound with the ending –ate, you must add the prefix per- along with the ending –ate, this is the highest oxidation state of the compound. For example Chlorate = ClO31- and Perchlorate = ClO41-.- ite- If the cation’s oxidation number is two less than the group number it ends in –ite. The group number for nitrogen is 5, the oxidation number for nitrogen in NO2- is 3+ making it Nitrite. Example SO32- = Sulfite, ClO21- = Chlorite. If an oxygen is taken away from the compound, decreasing the oxidation level, you add the prefix hypo- to the name of the compound. ClO1- = Hypochlorite.III. Finding the Chemical Formula- Last lecture we talked about predicting the chemical formulas of ions. Now lets try to predict the chemical formula when given the name of the compound.Ex) What is the chemical equation of Thallium (III) Bromide?Tl and Br <- First define the elements and notice that the use of roman numerals tells you that Thallium is a transition metal and that this is an ionic bond.Tl3+ Br1- <- The roman numeral III tells you that Thallium’s oxidation state is 3+ and since Bromide ends in –ide, you know that the oxidation state is the most common ion in its group on the periodic table1-.TlBr3 <- Now ‘criss-cross’ the oxidation numbers to get the chemical formula for Thallium (III) Bromide.Ex) What is the chemical equation of Nitrate?N and O <- First identify the elements (we know oxygen is present because nitrate is a polyatomic ion, ifit was just nitrogen it would be called nitride)N5+ and O? <- Here is where it gets more difficult because this is a polyatomic ion. The suffix is –ate so the oxidation number of nitrogen equals its group number 5. You will have to remember that the polyatomic ions that contain nitrogen either gain 1 electron or lose 1 electron, here it gains one electron giving it


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