Valence

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AP Chemistry A. Allan Chapter 8 Notes - Bonding: General Concepts 8.1 Types of Chemical Bonds A. Ionic Bonding 1. Electrons are transferred 2. Metals react with nonmetals 3. Ions paired have lower energy (greater stability) than separated ions B. Coulomb's Law 1. ? ? ? ? ? ? ? ? ?= - r QQ E nmJx 21191031.2 a. E = energy in joules b. Q1 and Q2 are numerical ion charges c. r = distance between ion center in nanometers d. negative sign indicates an attractive force C. Bond Length (covalent) 1. Distance at which the system energy is at a minimum 2. Forces at work a. Attractive forces (proton - electron) b. Repulsive forces (electron - electron, proton - proton) 3. Energy is given off (bond energy) when two atoms achieve greater stability together than apart

Campbell9thEdChapter2ChemicalContextofLife

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The Chemical Context of Life Chapter 2 Matter consists of chemical elements in pure form and in combinations called compounds Organisms are composed of matter Matter is anything that takes up space and has mass ? 2011 Pearson Education, Inc. Elements and Compounds Matter is made up of elements An element is a substance that cannot be broken down to other substances by chemical reactions A compound is a substance consisting of two or more elements in a fixed ratio A compound has characteristics different from those of its elements ? 2011 Pearson Education, Inc. Figure 2.3 Sodium Chlorine Sodium chloride The Elements of Life About 20?25% of the 92 elements are essential to life, but it varies among organisms Humans need 25 elements while plants only need 17 elements

AP Bio Chp 2 2

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AP Biology Reading Guide Chapter 2: The Chemical Context of Life Fred and Theresa Holtzclaw Copyright ? 2010 Pearson Education, Inc. - 1 - Name_______________________Period___________ Chapter 2: The Chemical Context of Life This chapter covers the basics that you may have learned in your chemistry class. Whether your teacher goes over this chapter, or assigns it for you do review on your own, the questions that follow should help you focus on the most important points. Concept 2.1 Matter consists of chemical elements in pure form and in combinations called compounds 1. Define and give an example of the following terms: matter element compound 2. What four elements make up 96% of all living matter?

Ap Bio Chp 2

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AP Biology Reading Guide Chapter 2: The Chemical Context of Life Fred and Theresa Holtzclaw Copyright ? 2010 Pearson Education, Inc. - 1 - Name_______________________Period___________ Chapter 2: The Chemical Context of Life This chapter covers the basics that you may have learned in your chemistry class. Whether your teacher goes over this chapter, or assigns it for you do review on your own, the questions that follow should help you focus on the most important points. Concept 2.1 Matter consists of chemical elements in pure form and in combinations called compounds 1. Define and give an example of the following terms: matter element compound 2. What four elements make up 96% of all living matter?

BIO CH 2 TEST

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Supramolecular chemistry

Chemical bond

Proton

Ionic bonding

Covalent bond

Hydrogen bond

Atom

Campbell's Biology, 9e (Reece et al.) Chapter 2 The Chemical Context of Life This chapter presents basic chemical principles for understanding the chemical context of living organisms, from atomic structure to the nature of chemical bonds and an introduction to chemical equilibrium. These questions focus on elements most important to life or the study of life, including the elements that comprise organic molecules and important trace elements. Some isotopes are important in geologic dating and in biological tracer studies. How elements participate in forming different types of chemical bonds is essential to mastering subsequent topics on the behavior and properties of biological molecules, structures, and energy metabolism. Multiple-Choice Questions

Principles of Chemistry Chapter 7

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Orbital hybridisation

Pi bond

Chapter 7: Chemical Bonding Section 7.3: The Covalent Bond Wednesday, October 1, 2014 1:55 PM Covalent bonds - attractive force resulting from the sharing of electrons between pairs of atoms ? Chemical Bonds and Energy ? Driving force between all bond formation is lowering overall energy (NOTE: attractive interactions lower potential energy) ? Typically in interactions between nonmetals! ? -point of minimum energy in a system = formation of covalent bond Bond energy - energy released when isolated atoms form a covalent bond Bond length - distance between the nuclei of bonded atoms ? Formation of a chemical bond always releases energy Bond strength is determined by the amount of energy released in the formation of that bond (more released energy means stronger bond) ?

Chapter 9

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Chemistry 1210: Introduction to General Chemistry Dr. Gina M. Florio 15 Nov. 2012 Jespersen, Brady, Hyslop Chapter 9 Chemical Bonding: General Concepts Ionic Bonds Ch. 9.2 Ionic bonds are the attraction between positive and negative ions in an ionic compound. e.g. NaCl An electron is transferred from the metal (Na) to the nonmetal (Cl): Ionic compounds form when metals and nonmetals react and they are held together by ionic bonds. Compounds (ionic and molecular) are formed due to a decrease (lowering) of the potential energy of system. Net energy change associated with the electron transfer reaction. So, why does NaCl (s) form at all? 2 Lattice Energy of Ionic Compounds Ch. 9.2 The energy needed to produce separated gaseous ions from one mole of the solid is the lattice energy:

campbell_ap_bio_practice_test_ch2

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Physics

Atom

Chemical reaction

Proton

ion

Covalent bond

Technology

Chapter?2 The?Chemical?Context?of?Life Multiple-Choice?Questions 1) About?25?of?the?92?natural?elements?are?known?to?be?essential?to?life.?Which?four?of?these?25?elements?make?up approximately?96%?of?living?matter? A) carbon,?sodium,?chlorine,?nitrogen B) carbon,?sulfur,?phosphorus,?hydrogen C) oxygen,?hydrogen,?calcium,?sodium D) carbon,?hydrogen,?nitrogen,?oxygen E) carbon,?oxygen,?sulfur,?calcium Answer: D Topic: Concept?2.1 Skill: Knowledge/Comprehension 2) Trace?elements?are?those?required?by?an?organism?in?only?minute?quantities.?Which?of?the?following?is?a?trace element?that?is?required?by?humans?and?other?vertebrates? A) nitrogen B) calcium C) iodine D) sodium E) phosphorus Answer: C Topic: Concept?2.1 Skill: Knowledge/Comprehension

Bob Jones PPT Notes -- Chapter 6b

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Section 6B Types of Bonds 1 Covalent Bonds usually nonmetals little or no ?EN (Therefore, atoms share electrons.) The 2 shared electrons are called a bonding pair. located between atoms most of the time Covalent Bonds The negative region between the atoms attracts the nuclei with an electrostatic force. Diatomic Elements H2 N2 O2 F2 Cl2 Br2 I2 ? triple bond ? double bond H N O Halogens Lewis Structures sometimes called dot diagrams show the valence e? only use a dash to represent a bonding pair Lewis Structures Cl2 + Cl Cl Cl Cl + Cl Cl Cl Cl Lewis Structures H2 + H H H H + H H H H Lewis Structures H2O + H O H + H O H + H O H + H O H Lewis Structures O2 O + O O O O + O O O Lewis Structures N2 N + N N N N + N N N Lewis Structures C2H2 + C C H + H + C C H H + C C H + H + C C H H

Anatomy Chemistry

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ion

Proton