...at the left of each statement, write the letter of the choice that best completes the statement or best answers the question. ______ 1. An ionic bond results from electrical attraction between a. cations and anions. b. atoms. c. dipoles. d. orbital. ______ 2. A nonpolar covalent bond is unlikely when two atoms of different elements join because the atoms are likely to differ in a. density. b. state of matter. c. electronegativity. d. polarity. ______ 3. Bond length is the distance between two bonded atoms at a. their minimum potential energy. b. their maximum kinetic energy. c. their maximum potential energy. d. one-half the diameter of the electron cloud. ______ 4. To draw a Lewis structure, it is not necessary to know a. which atoms are in the molecule. b. bond energies. c. the number of valence electrons for each atom. d. the number of atoms in the molecule. ______ 5. For multiple covalent bonds to form in molecules, the molecules must contain carbon, nitrogen, or a. chlorine. b. hydrogen. c. oxygen. d. helium. ______ 6. The principle that states that atoms tend to form compounds in which each atom has eight electrons in its highest occupied energy level is called the a. rule of eights. b. configuration rule. c. Avogadro principle. d. octet rule. Copyright © by Holt, Rinehart and Winston. All rights reserved. Modern Chemistry 51 Chapter Test Back Print Name Class Date Chapter Test B, continued ______ 7. An example of a molecule that cannot be represented...
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...Welcome to CH 125 Inorganic Chemistry for Microbiology Course Description This course covers inorganic reactions and phenomenon present in microbiological systems. The chemistry of the predominant biological elements of groups I to VII will be discussed. The students will explore the principles of inorganic chemical phenomenon including partially soluble substances, weak acids and bases, buffer systems and redox reactions. In addition, a basic understanding of the chemistry of the biologically important elements (H, C, N, O, K, Na, Ca, Mg, P, S, Cl and some transitional elements) will be explored. Course Learning Outcomes Upon successful completion, students will be able to: • Predict cation and anion concentrations of partially soluble solids dissolved in pure water and in a solution containing a common ion. • Apply knowledge of acids and bases in order to predict the pH of a solution containing a weak acid or base. • Demonstrate the use of common pH and redox indicators in microbiological media. • Select appropriate reagents to make a buffer having a desired pH. • Determine which compounds undergo the process of reduction and which undergo the process of oxidation. • Describe the basic chemistry of the predominant biologically important elements and their function(s) in microbiological systems. Dr. Andrew Baer Office Hours Monday: 10:30 am – 11:20 am Wednesday: 1:30 pm – 2:20 pm Thursday: 9:30 am – 10:20 am or by appointment Email:...
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...09. Net Ionic Equations tutorial.doc Introduction to Net Ionic Equations This tutorial will give you an algorithm for writing net ionic equations for aqueous reactions in general chemistry. Knowledge of the solubility rules is necessary to complete this tutorial. A list of solubility rules is provided at the end of the tutorial for review. Net ionic equations are necessary in chemistry for several reasons: 1. They show only those species undergoing chemical change – “spectator” ions are removed. 2. They must be used in any equilibrium calculation. 3. They allow chemical reactions to be combined properly. 4. Used when balancing half-reactions in oxidation-reduction chemistry. To take a chemical reaction in molecular form and rewrite as a net ionic equation is straight forward if you follow the steps given below. We will cover each step in detail using a common gas forming reaction from chemistry 1A. 1. Write the correct reactant and products – DO NOT BALANCE! The first step is to write the correct chemical formulas for the reactants and products, DO NOT BALANCE. The reaction will be balanced once the net-ionic equation is complete. As an example reaction, we will look at the aqueous reaction of sodium carbonate with acetic acid. Na2CO3 + HC2H3O2 ! NaC2H3O2 + H2O + CO2 (skeleton equation) The above reaction is called the skeleton equation; it contains only the correct chemical formulas of each reactant and product. Do not balance this equation! 2. Add phase...
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...Chemistry laboratory Pr. Zineb EDFOUF 3- Compound types CH 1213 Chemistry I Name: …………………………. Group: ….......................... Purpose: To examine the difference between ionic and covalent compounds and understand how their properties give rise to this categorization Introduction: It is amazing what early chemists accomplished even without an understanding of atomic make-up. Reading old chemistry textbooks shows how they justified some of their conclusions, which, with a few exceptions, were right on target. Some discussed the octet rule in terms of “valencies”, and they have it exactly right. What is interesting about this is that at that time they talked about this new sub-atomic particle that they were tentatively calling the “electron”. Another thing they had correct was the categorization of compounds into “covalent” and “ionic”. In class, you have discussed these compounds in terms of electrons, wherein ionic compounds transfer electrons and covalent compounds share electrons. How did the early chemists classify compounds, though, when they did not know what electrons were? They used properties, such as solubilities, melting points, and conduction. Solubility helps us to classify compounds as polar or non-polar, because, as a general rule, polar solutes dissolve in polar solvents (like water), while non-polar solutes dissolve in non-polar solvents (like oils). Conductivity means whether or not a compound will conduct electricity when it is dissolved...
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...Chemistry 1B Experiment 16 77 16 Qualitative Analysis Introduction The purpose of qualitative analysis is to determine what substances are present in detectable amounts in a sample. This experiment has two parts. In the first part, you will analyze an unknown solution for the presence of seven common ions. In the second part, you will test an unknown solid to determine which of two possible identities is correct. Part I. Spot Tests for Some Common Ions A simple approach to the qualitative analysis of an unknown solution is to test for the presence of each possible ion by adding a reagent which will cause the ion, if it is in the sample, to react in a characteristic way. This method involves a series of “spot” tests, one for each ion, carried out on separate samples of the unknown solution. The difficulty with this way of doing qualitative analysis is that frequently, particularly in complex mixtures, one species may interfere with the analytical test for another. Although interferences are common, there are many ions which can be identified in mixtures by simple spot tests. In this experiment we will use spot tests for the analysis of a mixture which may contain the following commonly encountered ions in solution: CO32– SO42– PO43– SCN Cl – – carbonate sulfate phosphate thiocyanate chloride acetate ammonium C2H3O2– NH4+ 78 Chemistry 1B Experiment 16 The procedures we involve simple acid-base, precipitation, complex ion formation or oxidation-reduction...
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...consists of a dense central nucleus surrounded by a cloud of negatively charged electrons Atoms are made up of three basic particles: Protons-carries a positive charge Neutrons-carry no charge Electrons-carry a negative charge and encircles the nucleus. (http://education.jlab.org/atomtour/listofparticles.html) 2. Element A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. http://en.wikipedia.org/wiki/Chemical_element 3. Compound A chemical compound is a pure chemical substance consisting of two or more differentchemical elements[1][2][3] that can be separated into simpler substances by chemical reactions.[4] Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms[3] that are held together in a defined spatial arrangement bychemical bonds. Chemical compounds can be molecular compounds held together bycovalent bonds http://en.wikipedia.org/wiki/Chemical_compound 4. Mass number The mass number (A), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. http://en.wikipedia.org/wiki/Mass_number 5. atomic number the atomic number (also known as the proton number) is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus http://en.wikipedia.org/wiki/Atomic_number 6...
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...CHEMISTRY CHEMISTRY (CLASSES XI–XII) Rationale Higher Secondary Stage is the most crucial stage of school education because at this stage specialised discipline based, content oriented courses are introduced. Students reach this stage after 10 years of general education and opt for Chemistry with a purpose of mostly for pursuing their career in basic sciences or professional courses like medicines, engineering, technology and studying courses in applied areas of science and technology at tertiary level. Therefore, at this stage, there is a need to provide learners with sufficient conceptual background of Chemistry, which will make them competent to meet the challenges of academic and professional courses after the higher secondary stage. National Curriculum Framework for School Education – 2005 recommends a disciplinary approach with appropriate rigour and depth with the care that syllabus is not heavy and at the same time it is comparable to the international level. It emphasizes a coherent focus on important ideas within the discipline that are properly sequenced to optimize learning. It recommends that theoretical component of Higher Secondary Science should emphasize on problem solving methods and the awareness of Syllabus for Secondary and Higher Secondary Levels 22 historical development of key concepts of science be judiciously integrated into content. The present exercise of syllabus development in Chemistry at Higher Secondary Stage is based on this framework...
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...Assignment #3 Documented Essay: Chemistry SCI 110 Professor Denise Stiglich Describe the difference between a mixture and a compound As described in the text book, a mixture has unlike parts and a composition that varies from sample to sample (Tillery, p. 200). The book provides an example of sand from a beach. It has a variable mixture of such things as bits of rocks, minerals and sea shells (Tillery, p. 200). A compound is a pure substance that can be decomposed by a chemical change into simpler substances with a fixed mass ratio (Tillery, p. 201). So the difference is that a compound is made up of two or more elements that have a composition that is constant. And a Mixture is an aggregate of two or more substances that are not chemically united. Suppose that you have a pure substance. How can you tell whether it is a compound or an element? The way you can tell if a pure substance is a compound or an element is that an element is made up of one kind of atom. For example, gold is an element. If you were to keep cutting the gold until you only had one particle of gold that couldn’t be cut anymore, you would have one atom. A substance that is a compound has two or more elements. For example, water is a compound that is made up of two different elements, hydrogen and oxygen. What is the difference between an ionic and a covalent bond? As stated in the text book, an ionic bond is defined as the chemical bond of...
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...Organic Chemistry Laboratory – CH 200L (2012 – 2013) 2A-BC Group 4 Experiment 1 Title of the Experiment Juan C. dela Cruz*, Pedro R. Reyes and Pablo S. Santos Department of Biochemistry, Faculty of Pharmacy University of Santo Tomas, Espana Street, Manila 1008 Date Submitted: ------------------------------------------------- Abstract The atoms in a compound are held together by a chemical bond. There are two types of chemical bond: ionic and covalent bond. An ionic or electrovalent bond results from the electrostatic attraction between metal and non-metal atoms by the transfer of electrons. _____________________________________________________________________________________ Introduction The atoms in a compound are held together by a chemical bond. There are two types of chemical bond: ionic and covalent bond. An ionic or electrovalent bond results from the electrostatic attraction between metal and non-metal atoms by the transfer of electrons. One example is the formation of bond between a sodium metal atom and a chlorine non-metal atom [1]. In contrast, covalent bond involves the sharing of valence electrons between non-metal atoms. A covalent bond becomes polar when there is unequal sharing of bonding electrons. This happens when the elements involved in the bond has a significant difference in their electronegativity, such as in hydrochloric acid, HCl. Equal distribution of bonding electrons leads to the formation of a non-polar covalent bond. ...
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...Chapter 2 “The Chemistry of Life” Worksheet ANSWERS Section Review 2-1 1. Protons; neutrons 2. electrons 3. neutrons 4. electrons 5. ionic 6. The two main types of chemical bonds are ionic and covalent bonds 7. At atom becomes an ion when it gains or loses electrons 8. Electrons and protons are both subatomic particles; however, they have different charges and locations within the atom. 9. When atoms are joined together by covalent bonds, the structure that results is a molecule. 10. The property of radioactive isotopes that is useful for dating is that they break down at a constant rate over time. Section Review 2-2 1. a 2. b 3. c 4. c 5. a 6. b 7. c 8. Polarity in a water molecule is caused by an uneven distribution of electrons between the oxygen and hydrogen atoms. 9. the concentration of H+ ions determines whether a solution is acidic or basic 10. Capillary action is the effect of water rising in a narrow tube against the force of gravity. 11. Two types of mixtures are solutions and suspensions 12. A base is a compound that can form a basic solution when dissolved. 13. Acidic solutions have a lower pH than pure water. This is due to the greater concentration of H+ ions than pure water. 14. Strong acids and bases are dangerous to cells. Buffers are dissolved compounds that help prevent sharp, sudden swings in pH. Section Review 2-3 1. Carbohydrates 2. Proteins ...
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...We recently did two labs where we were given the task of observing single-replacement and double-replacement reactions. This paper has background information on the different types of chemical reactions, as well as the chemistry behind the two reactions we observed in lab. A chemical reaction is a process that is characterized by a chemical change in which the reactants (starting products) are different from the products. Chemical reactions involve the breaking of old bonds and the formation of new bonds. They can result in the formation of precipitates, changes in color, production or absorption of heat, or formation of gas bubbles. Chemical reactions can be placed in the following five categories: (i) synthesis (ii) decomposition...
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...following shows the Table of Contents from Paradis’ Explorations in Conceptual Chemistry: A Student Activity Manual. The numbers in the last column show the related sections students should read in John Suchocki’s Conceptual Chemistry 5th ed. Unit 1: The particulate nature of matter Activity 1a: Matter is particulate (low-tech evidence) 1.1-1.2, 2.1, 2.2 Activity 1b: Matter is particulate (high-tech evidence) 5.1 Unit 2: Phases, phase changes, and the effect of heat on matter Activity 2a: The properties of solids, liquids and gases 2.3, 2.4, 2.7 Activity 2b: Understanding atmospheric pressure 16.5 Activity 2c: Heat and the motion of sub-microscopic particles 2.5, 2.6 Activity 2d: Absolute zero and the Kelvin temperature scale 2.6 Activity 2e: Exploring the phase changes 2.7, 8.2-8.6 Activity 2f: The difference between boiling and evaporation 8.4 Unit 3: An overview of the periodic table Activity 3: Properties of the elements and the periodic table 3.2, 3.3, 2.2 Unit 4: The structure of the atom Activity 4a: The nucleus, isotopes, and atomic mass 4.2, 4.3, 4.4 Activity 4b: The electrons and the shell model 4.2, 4.5-4.8 Unit 5: An introduction to ionic, covalent, and metallic bonding Activity 5: Conductivity and models of chemical bonding 3.4, 6.2-6.5 Unit 6: Exploring covalent compounds (molecules) Activity 6a: Molecules and lewis dot structures 6.5 ...
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...Chemistry note on thermodynamics A born haber cycle= a thermochemical cycle that includes all the enthalpy changes involved in the formation of an ionic compound. e.g the born haber cycle for sodium chloride if we know any five we can calculate the other: starting from the elements in their standard states. Na s -> Na g +108kjmol-1 ½ CL2-> Cl g +122kjmol-1 Na g -> Na+ + e- +496kjmol-1 Cl g + e+ -> Cl- g -349kjmol-1 Na s + ½ Cl2 -> NaCl s -411kjmol-1 When drawing the born haber cycles: * Make up a rough scale 1 line of paper to 100kjmol-1 * Plan out roughly first to avoid going off the top or bottom of the paper. The zero line representing elements in their standard state will need to be in the middle of the paper. * Remember to put in the sign of each enthalpy change and an arrow to show its direction. Possitive enthalpy changes go up, negative enthalpy changes go down. Using born haber cycle we are able to see the formation of an ionic compound from its elements is an exothermic process. This is mainly due to the large amount of energy given out when the lattice forms. 1. Elements in their standard states. This is the energy zero of the diagram 2. Add in the atomisation of sodium. This is positive, drawn uphill. 3. Add in the atomisation of chlorine. This is positive, drawn uphill. 4. Add in the ionisation of sodium, also posstive, drawn uphill. 5. Add in the electron affinity of chlorine. This is negative...
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...a polar arrangement of the oxygen and hydrogen atoms—one side (hydrogen) has a positive electrical charge and the other side (oxygen) has a negative charge. A polar bond is a covalent bond between two atoms where the electrons forming the bond are unequally distributed. This causes the molecule to have a slight electrical dipole moment where one end is slightly positive and the other is slightly negative. "Like dissolves like" is an expression used by chemists to help them remember how solvents work. The expression refers to "polar" and "nonpolar" solvents and solutes. For example water is polar and Oil is non polar thus water will not dissolve oil. Therefore nonpolar molecules don't dissolve very well in water, including many organic compounds, such as fats and waxes. Water molecules can become attracted to several other types of molecules due to its polar bonds. Water can become so heavily attracted to a different...
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...AS/A Level GCE GCE Chemistry A OCR Advanced Subsidiary GCE in Chemistry A H034 OCR Advanced GCE in Chemistry A H434 Vertical black lines indicate a significant change to the previous printed version. © OCR 2008 version 2 – February 2008 QAN 500/2425/5 QAN 500/2347/0 Contents 1 About these Qualifications 1.1 1.2 1.3 1.4 1.5 The Three-Unit AS The Six-Unit Advanced GCE Qualification Titles and Levels Aims Prior Learning/Attainment 4 4 4 5 5 5 2 Summary of Content 2.1 2.2 AS Units A2 Units 6 6 7 3 Unit Content 3.1 3.2 3.3 3.4 3.5 3.6 AS Unit F321: Atoms, Bonds and Groups AS Unit F322: Chains, Energy and Resources AS Unit F323: Practical Skills in Chemistry 1 A2 Unit F324: Rings, Polymers and Analysis A2 Unit F325: Equilibria, Energetics and Elements A2 Unit F326: Practical Skills in Chemistry 2 8 8 20 38 40 51 62 4 Schemes of Assessment 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 AS GCE Scheme of Assessment Advanced GCE Scheme of Assessment Unit Order Unit Options (at AS/A2) Synoptic Assessment (A Level GCE) Assessment Availability Assessment Objectives Quality of Written Communication 64 64 65 66 66 66 67 67 68 5 Technical Information 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Making Unit Entries Making Qualification Entries Grading Result Enquiries and Appeals Shelf-life of Units Unit and Qualification Re-sits Guided Learning Hours Code of Practice/Subject Criteria/Common Criteria Requirements Arrangements for Candidates with Particular...
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