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CSU CHEM 111 - Exam 2 Study Guide

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Chromium (Cr), Molybdenum (MO), Copper (Cu), Silver (Ag), Gold (Au)CHEM 111 1nd EditionExam # 2 Study Guide Lectures: 10 - 19Lecture 10: Sizes and Shapes of Atomic Orbitals; 3.7 (September 17) Give a brief explanation and comparison of orbitals. How many are there of each? Which one has the lowest potential energy?There are four types of orbitals: s, p, d and f. There is one s orbital in each shell, three p orbitals, five d orbitals and seven f orbitals. Each orbital has the capacity to hold two electrons. Of all the orbitals and subshells, 1s has the lowest potential energy. What is the order of increasing energy levels? (s<p<d<f)Shapes and Sizes of OrbitalsOrbitals have characteristic three-dimensional sizes,shapes and orientations. All s orbitals are spheresthat increase in size with increasing values of n. Each of the three p orbitals has two lobes along the x-, y-, or z- axis. The five d orbitals in the > 3 shells come in two forms: four are shaped like a four-leaf clover, and the fifth has two lobes oriented along the z-axis and a torus surrounding the middle of the two lobes.Lecture 11: Electron Configurations; 3.78 (September 19) Aufbau principle- electrons fill the lowest-energy atomic orbitals of a ground-state atom firstEffective nuclear charge (Zeff)- the net nuclear charge felt by outer-shell electrons when they are shielded from the full nuclear charge by inner-shell electrons- Greater Zeff means lower energy- Electrons in the furthest orbital feel the smallest ZeffElectron configuration- the distribution of electrons among the orbitals of an atom or ionValence electrons- the outer most electrons involved in bond formationUnderstand Hund’s rule.Lecture 12: Ions, Size Trends; 3.9-10 (September 22)Describe the periodic trends of atomic size and explain why this is.The sizes of atoms increase as you move from the top of the periodic table to the bottom. This isdirectly related to the increasing atomic numbers in a group of elements because valence-shell electrons with higher n values are, on average, farther from the nucleus. Generally speaking, if you have two elements in the same group, the element with the higher atomic number will be larger in size as well. The size of atoms also decreases as you move from left to right, in a row, on the periodic table because the valence electrons experience higher effective nuclear charges (Zeff). Comparing the sizes of anions, cations, and their parents.Anions are larger than their parent atoms due to additional electron-electrion repulsion, but cations are smaller than their parent atoms—sometimes much smaller when all the electrons inthe valence shell are lost..Lecture 13: Other Periodic Trends; 3.11-12 (September 24)What is ionization energy? Explain its trends on the periodic table.The amount of energy needed to remove 1 mol of electrons from 1 mole of atoms or ions in thegas phase. IE values generally increase with increasing Zeff across a row and decrease with increasing atomic number down a group in the periodic table. Define electron affinity (EA) The energy change that occurs when I mole of electrons combines with 1 mole of atoms or ions in the gas phase. The EA values of many main group elements are negative, indicating that energy is released when they acquire electrons.Orbitals fill up in the following sequence: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p,Some elements don’t follow the rule of filling up orbitals in the same sequence. Which elements are these and why do they do that?Chromium (Cr), Molybdenum (MO), Copper (Cu), Silver (Ag), Gold (Au)In forming transition metal ions, electrons are removed to maximize the number of d electrons; there is enhanced stability in half-filled and filled d subshells. Lecture 14: Types of Bonds; 4.1 (September 26)Describe ways in which covalent, ionic, and metallic bonds are alike and ways in which they differ.A chemical bond results from two ions being attracted to each other (an ionic bond) or from two atoms sharing electrons (a covalent bond). The atoms in metallic solids pool their electrons in, forming metallic bonds.Calculate the relative strengths of ion-ion interatctionsLecture 15: Nomenclature; 4.2 (September 29)How do you name molecular and ionic compounds and write their formulas.Ionic CompoundsTo name ionic compounds, first write the name of the cations parent element, and then write the name of the anion’s parent element. Change the ending of the name of the second element to –ide. Roman numerals in parentheses indicate the charges of transition metal cations. The names of oxoanions (polyatomic ions containing oxygen atoms) end in –ate or –ite and may have a per- or hypo- prefix to indicate the relative number of oxygen atoms per ion. Molecular CompoundsTo name binary molecular compounds, first write the name of the element that is to the left of, or, if the elements are in the same group, below the other on the periodic table. Then write the name of the other element, changing its ending to –ide. Prefixes indicated the number of atomsof each element per molecule. The names of solutions of binary acids (general formula HX) begin with the prefix hydro- followed by the name of the element X, but end in –ic followed by the word acid. The names of the oxoacids are similar to the names of their oxoanions, but their endings change from –ate to –ic acid and from –ite to –ous acid. Lecture 16: Lewis Structure I; 4.3 (October 1)Understanding Lewis Structures and How to Draw ThemLewis symbols use dots to represent paired and unpaired electrons in the ground states of atoms. The number of unpaired electrons indicates its bonding capacity (the number of bonds the element is likely to form). Atoms become stabile when they have 8 valence. A Lewis structure shows the bonding pattern in molecules and polyatomic ions; pairs of dots represent lone pairs of electrons that do not contribute to bonding. A single bond consists of a single pair of electrons shared between two atoms; there are two shared pairs in a double bond, and threeshared pairs in a triple bond.How to: Connect the atoms with single covalent bonds, distributing the valence electrons to give each non-central atom 8 valance electrons (except for 2 for H); use multiple bonds where necessary to complete the central atom’s octet.Lecture 17: Lewis Structures II, Electronegativity; 4.4 (October 3)What happens when two elements are sharing atoms unequally?


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