9C.184.108.40.206 Properties & Bonding
Explain how elements combine to form compounds through ionic and covalent bonding.
Use IUPAC (International Union of Pure and Applied Chemistry) nomenclature to write chemical formulas and name molecular and ionic compounds, including those that contain polyatomic ions.
MN Standard in Lay Terms
The manner in which atoms' electrons interact with other atoms' electrons to form chemical bonds will determine the chemical and physical properties of compounds of those elements. Compounds are named in a systematic way related to the type of bonding.
A bond is a force that holds groups of two or more atoms together and makes them act as a unit. The force is between valence electrons which can be transferred or shared. How the electrons are arranged in atom and then in the compound determine the characteristics and chemical behavior of the compound.
An ionic bond is formed by transferring electron(s) between a metal and nonmetal. Ionic compounds conduct electricity in solution and have high melting points.
Covalent bonds share valence electrons between nonmetals. Covalent compounds (molecules) do not conduct electricity in solution and have low melting points.
Be able to name ionic compounds, including those with polyatomic ions, and molecular compounds according to the IUPAC system.
MN Standard Benchmarks
9C.220.127.116.11 Explain how elements combine to form compounds through ionic and covalent bonding.
9C.18.104.22.168 Use IUPAC (International Union of Pure and Applied Chemistry) nomenclature to write chemical formulas and name molecular and ionic compounds, including those that contain polyatomic ions.
12BPS2.1- Atoms interact with one another by transferring or sharing electrons that are furthest from the nucleus. These outer electrons govern the chemical properties of the element.
12BPS2.3 - Bonds between atoms are created when electrons are paired up by being transferred or shared. A substance composed of a single kind of atom is called an element. The atoms may be bonded together into molecules or crystalline solids. A compound is formed when two or more kinds of atoms bind together chemically.
12BPS3.3 A large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Radical reactions control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions.
12BPS2.4 The physical properties of compounds reflect the nature of the interactions among its molecules. These interactions are determined by the structure of the molecule, including the constituent atoms and the distances and angles between them.
Benchmarks of Science Literacy
The number of protons in the nucleus determines what an atom's electron configuration can be and so defines the element. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons. 4D/H2*
Atoms often join with one another in various combinations in distinct molecules or in repeating three-dimensional crystal patterns. 4D/H7a
The configuration of atoms in a molecule determines the molecule's properties. Shapes are particularly important in how large molecules interact with others. 4D/H8
Structure of Matter: Volume 1 (blue) pages 54-61
Atoms and Molecules Map
Conservation of Matter Map
States of Matter Map
Chemical Reactions Map
NAEP 09 Science Frameworks: Physical Science, pages 25- 38
Common Core Standards
2010 Literacy Standards - Reading Benchmarks: Literacy in Science and Technical Subjects 6-12
Common Core Language Arts Standards: Students can write a laboratory report in the proper form and using their knowledge of technical writing skills. Common Core Standards addressed:
RST.9-10-1. Cite specific textual evidence to support analysis of science and technical texts, attending to the precise details of explanations or directions.
RST.9-10-2. Determine the central ideas or conclusions of a text; trace the text's explanation or description of a complex process, phenomena or concept; provide an accurate summary of the text.
RST.9-10.3. Follow precisely a complex multistep procedure when carrying out experiments; taking measurements or performing technical tasks, attending to special cases or exceptions defined in the texts.
- Students believe there is something between atoms of compounds rather than a force of attraction
- Bonding must be either 100% ionic or covalent
- Covalent bonds must be weak since covalent molecules have relatively low melting points
- Students get confused when talking about the forces within molecules versus forces between molecules
Ms. Lewis introduces the new unit by first reviewing how to determine the number of valence electrons of an atom by what column each element is located in on the periodic table. She also reminds them of where the metals and nonmetals are each located. She lists several elements on the board and instructs students to draw the dot diagrams for each. "The rule," she explains, "is to match up pairs so that each have the same number of electrons as the nearest noble gas (this can be achieved by going either forward or backward) by either sharing, losing or gaining electrons." She uses sodium and chlorine as an example. Because each is left charged as they lose and gain one electron respectively, they then "stick" together like poles of a magnet. This is called ionic bonding. Students are then given a puzzle where they do the same type of matching for several other elements. She then uses the hydrogen atom as an example and asks the students what would happen if they combined. Since there are only two electrons available between the two them, they must "share" electrons which makes a covalent bond.
The next day, Ms. Lewis starts the class with a demonstration showing different types of substances and whether they conduct electricity or not. Using a light bulb she tests salt (sodium chloride) water and sugar water to see whether either solution will get the bulb to light up. One solution does and the other does not. Ms. Lewis asks students why they think this happened and writes all ideas on the board. Ms. Lewis discusses how electricity flows because of charged particles. She then has the students pair up and come up with the similarities and differences of each of the solutions. Ms. Lewis discusses with the class, the concepts of ionic and covalent bonding, the different properties each substance has and what type of element each bond is made up of (metal or nonmetal). Ms. Lewis gives the class time to practice identifying whether a compound is ionic or covalent (molecular) for homework. (Benchmark: 9C.22.214.171.124)
After the students are able to identify the type of compound, Ms. Lewis instructs them on the system of naming that chemistry uses (IUPAC). To help keep ideas separate, students first practice naming ionic compounds only. They start first with simple compounds, move onto polyatomic ions and finally to metals that have multiple oxidation numbers. Although she shows them the Latin names, Ms. Lewis only requires the students to be able to name these metals with the stock system using Roman numerals. At the same time, students are going from names to formulas as well as formulas to names. This takes several days and Ms. Lewis is careful to use formative assessment to be sure that all students have acquired this skill. The class ends the week with a contest "March Madness" with a tournament of 64 compounds using the ideas learned this week by students. (Prizes, treats or points can really motivate the kids!)
The next week, Ms. Lewis uses the ball and stick molecule kits to help kids visualize the three dimensional aspects of compound. As they build certain molecules, she explains the molecular naming system using prefixes. The goal of their homework is to be able to go between names and formulas of molecular compounds.
Suggested Labs and Activities
1. Common Labs for this unit include (Good Source is Flinn Topic Labs)
a. building ball and stick models for molecules
b. basic precipitate reaction lab - formulas and naming as a focus
2. Activities for chemical compounds, writing chemical formulas and related topics Chemical compounds (Benchmark: 9C.126.96.36.199).
3. Chemical Bonding Chemical Bonding lab activity (Benchmark: 9C.188.8.131.52)
4. Chemical bonds Includes illustrations and explanations of bonding (Benchmark: 9C.184.108.40.206)
5. Excellent site for games related to chemical bonding The Bonding Game (Benchmark: 9C.220.127.116.11)
1. Videos - Online videos can be a great way to engage students at the start of a unit. A google search of key words in the content area can yield a variety of demonstration sites as well as full length videos.
a. difference between ionic and covalent bonds
b. making of ionic sodium chloride and covalent water (Benchmark: 9C.18.104.22.168)
c. Mr. Kent's Chemical Demonstrations - Several pages of well done you tube videos of various reactions to show using an LCD when materials are too dangerous or costly to perform experiments in class.
d. Exploscience.com - Dynamic Chemistry- This site has a series of videos in one place showing several chemical reactions in action illustrating how bonds affect behavior of compounds. It could be used to replace demonstrations if materials are not available or safety is an issue.
e. World of Chemistry Series - These videos are not modern but give a good foundation of basic information after the class has had some experience with the content. It can be used as a summary of the unit or possible review. Students could come up with a series of questions or use worksheets.
i. Chemical Bonds - The differences between ionic and covalent bonds are explained by the use of scientific models and examples from nature
ii. Molecular Architecture - The program examines isomers and how the electronic structure of a molecule's elements and bonds affects its shape and physical properties
iii. The Age of Polymers - How chemists control the molecular structure to create polymers with special properties is explored
2. Science Literacy: Chemmatters - Published by the American Chemical Society, has relevant, fast reading articles to tie topics in the classroom to the real world of students. Teachers' guides with questions and additional background information are also available.
3. NSTA series of Formative Assessment Probes
Uncovering Student Ideas in Science
a. Chemical Bonds: Volume 2 pages 71-75
b. Salt Crystals: Volume 4 pages 39-43
4. Learning4Mastery.com - Topic 8: Chemical Bonding and the Atomic Theory. Podcasts for students available in 15 minute clips.
5. Using a classroom set of small whiteboards can help an instructor check for understanding. Dot diagrams and shapes can be done nicely since they are larger and easy to erase for rearrangement of electrons in a molecule.
6. The Best Practices of Science Teaching - Many of the best practices are summarized and examples are given in the chapter "Guided inquiry in the science classroom" by Minstrell, J. & Kraus, P. found in How Students Learn: History, Mathematics, and Science in the Classroom. (M. Suzanne Donovan and John D. Bransford, Editors) Washington, DC: National Research Council (2005). Other best practices are to be found in Robert Marzano's Classroom Instruction that Works. (2001). ASCD
Chemical Bonding Tutorial Types of Chemical Bonding (Benchmark: 9C.22.214.171.124)
This site has 15 minute podcasts for every topic in a general chemistry course. They are 15 minute segments posted on YouTube for students to use independently or as a tutorial supplement for classroom instruction.
Nancy Clark's Website - Compounds - the materials and resources that were collected and catagorized during her 37 years as a teacher
Normal Community High School Chemistry: Bonding and Nomenclature - This website is designed as a service to teachers and as a forum for collaboration of high school teachers that want to improve the quality of their classrooms. This website posts only high quality material on a variety of topics which can be quickly downloaded and implemented into your classroom. In addition any collaborating teachers are welcomed and encouraged to post their own developed lesson plans
ChemTours developed specifically for Chemistry, 2nd Edition. These use animation and interactive exercises to help develop your understanding of fundamental concepts.
Mark Bishop's Online Chemistry Textbook Includes lessons, powerpoints, and tutorials along with typical written text.
ChemChalkboard Great resource for chemistry units, includes power points (many with animations), activities and labs
Awesome Science Teachers Resources Includes lessons, labs and activities pertinent to chemistry
Making Sense of Secondary Science - research into children's ideas
Particle Models of Elements and Compounds - page 96-97
- ionic bond - transfer of electrons from a metal to a nonmetal
- covalent bond - sharing of valence electrons between nonmetals
- polar covalent bond - unequal sharing of electrons, so the more electronegative element has a slight negative charge and the less electronegative element has a slight positive charge
- Lewis structure - a representation of a molecule that shows how the valence electrons are arranged among the atoms in the molecule
- polyatomic ion - a charged group of covalently bonded atoms
- ionic compound - made up of metal and nonmetal that transfer electrons to complete octet
- molecular compound - two or more nonmetals that share electrons to complete octet
PHET simulation site. Various simulations to explore for states of matter and gas behavior. Works very well as a demonstration on an interactive white board. Many simulations are available in translated versions.
Vernier Labs for Chemistry - this is the general site for all things vernier. If you are just beginning to use digital collection tools, look at the starter kit that Vernier puts together.
Chemical Education Research Group - site with animation of bonding and polarity
Positive and negative numbers are manipulated for balancing charges - students need to understand that two equal numbers with opposites signs are equal to zero.
Assessment of Students
Which of the following pairs will form a covalent bond?
- a. Ca, Cl b. Mg, N c. P, O d. Li, Cl
knowledge and application
Which type of bonded substance has the highest melting points.
- a. metallic b. covalent c. hydrogen d. ionic e. all compounds have the same melting points
A bond in which one of the atoms share a pair of electrons is a(n) _____ bond.
- a. ionic b. metallic c. covalent d. hydrogen
Name the following compounds:
- a. NaNO3 _____________ (sodium nitrate)
- b. FeCl3 _________________ (iron (III) chloride)
- c. N2O3 ___________________ (dinitrogen trioxide)
Write correct formulas for the following compounds:
a. magnesium bromide __________ (MgBr2)
b. lead (II) sulfate _______________ (PbSO4)
c. carbon tetrachloride ____________ (CCl4)
Explain how a sodium atom uses its electrons to bond to a chlorine to make salt.
The sodium atom has one more valence electron than a Neon atom. Chlorine atoms have one less electron than Argon atoms. The sodium atom will lose an electron to the chlorine atom which gives both atoms the same electron structure as one of the noble gases. Once sodium loses an electron the atom becomes a positive ion and the chlorine which has gained a negatively charged electron becomes negative. The two opposite charges attract which is the force holding them together or Ionic Bond.
Assessment of Teachers
How might a teacher respond to a student's challenge: "Why do we need to learn this?"
Understanding how chemical compounds are bonded together will help students understand how substances around them interact and affect them.
Why you can burn/melt sugar but not salt
How electrolytes work in their bodies
Be able to figure out what type of ingredients are in the food they consume.
How is this concept important to other disciplines, biology for example?
The chemical bonds holding important molecules like ATP and DNA together
How electrolytes work in the body
Are there any everyday examples to help students understand this concept?
Administrators would see the students engaged in discrepant events, labs, lecture, online simulations videos and hands-on activities.
White boards or clickers should be common as teachers use methods to get all students participating in naming and formula formative assessments. Naming and formulas are a MUST for students in order to continue to be successful in chemistry.
Struggling and At-Risk
At risk students should be engaged with hands on activities as often as possible. It may be difficult for them to visualize the abstract manner in which atoms bond. Have these students build models using concrete items such as Styrofoam balls.
Using legos of multiple sizes or cut out shapes help students grasp the idea of balancing charges in ionic compounds without having to use positive and negative numbers.
Teaching Science to ELL - part 1 and 2 - NSTA journal The Science Teacher articles available for free on ELL language and learning.
The Sourcebook for Teaching Science - Strategies, Activities, and Instructional Resources
The science classroom is often a frustrating place for English language learners. Science has a complex vocabulary that is difficult even for native English speakers to learn. Difficulty learning English should not be confused with an inability to think scientifically. Many of the strategies that are useful for English language learners are effective for differentiating instruction for others.
Teaching Science to English Language Learners: Building on Students' Strengths - Can a student's cultural background support learning in science? Or is concentrating on the specialized vocabulary of science the best way to help English language learners learn science? This book addresses these and other pressing questions you face when working with students whose linguistic and cultural backgrounds, as well as their languages, are different from your own.
Have students make a poster, clay model, or other representation of the properties of substances with metallic, ionic, and covalent bonds. Be sure students label their representations with the name of bond type. (Modern Chemistry Holt, Rinehart and Winston 2006)
Have your student note various types of material (such as breakfast cereals) around the house and determine if these are ionic or covalent compounds from the formulas on the labels.