YOUNGSTOWN CITY SCHOOLS

SCIENCE: CHEMISTRY

UNIT #4 “IONIC AND COVALENT BONDING” UNIT PLAN (3 WEEKS) 2013-2014SYNOPSIS: In this unit, students build on their learning from the Periodic Table unit and extend to bonding. Students work through a series of labs and readings to understand ionic and covalent bonds. Students work with Lewis Dot diagrams, Ball-Stick lab as well as polarity. Students conduct an error analysis of VSEPR to determine if the information given to them is correct. If there are errors, the students must correct the chart and explain their reasoning in addition to correcting the information

ENABLERS ionic, covalent, lattices, electronegativity, valence electrons, polar, metallic bonding, atomic numbers, masses, polyatomic ions, Lewis structures, VSEPR theory

STANDARDSIV. IONIC AND COVALENT BONDING

A. Atoms with unpaired electrons tend to form ionic and covalent bonds with other atoms forming molecules, ionic lattices or network covalent structures

B. Electron configurations, electronegativity values, and energy considerations will be applied to bonding and the properties of materials with different types of bonding

1. Atoms of many elements are more stable as they are bonded to other atoms. In such cases, as atoms bond, energy is released to the surroundings resulting in a system with lower energy.

2. An atom’s pattern of valence electrons determines how an atom interacts with other atoms3. Using the periodic table, formulas of ionic compounds can be predicted including ionic compounds from groups 1,2, 17,

hydrogen and oxygen and polyatomic ions if given the formula and charge of the polyatomic ion.C. Molecules, ionic lattices, and network covalent structures have different, yet predictable, properties that depend on the identity of

the elements and the types of bonds formed1. Differences in electronegativity values can be used to predict where a bond fits on the continuum between ionic and

covalent bonds2. Polarity of a bond depends on the electronegativity difference and the distance between the atoms (bond length)

D. Polar covalent bonds are introduced as an intermediary between ionic and pure covalent bonds1. Metallic bonding is introduced to explain many of the properties of metals (e.g., conductivity)2. A substance may contain more than one type of bond

E. Compounds containing carbon are an important example of bonding1. Carbon atoms can bond together and with other atoms, especially hydrogen, oxygen, nitrogen, and sulfur to form chains,

rings, and branching networks that are present in a variety of compounds, including synthetic polymers, fossil fuels, and the large molecules essential to life

2. Given the name of an ionic or covalent substance, formulas can be writtenF. Many different models may be used to represent compounds including chemical formulas, Lewis structures, and ball and stick

structures1. These models may be used to visualize atoms and molecules and to predict the properties of substances2. Each type of representation provides unique information about the compound3. Different representations are better suited for particular substances

G. Lewis structures and VSEPR theory can be used to predict the three-dimensional electron pair and molecular geometry of compounds

1. Lewis structures and molecular geometries will only be constructed for the following combinations of elements: hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, and the halogens.2. Organic nomenclature is reserved for more advanced courses

LITERACY STANDARDSRST.5: Analyze how the text structures information or ideas into categories or hierarchies, demonstrating understanding of the information or ideas

RST.7: Integrate and evaluate multiple sources of information presented in diverse formats and media (e.g., quantitative data, video, multimedia) in order to address a question or solve a problem.

MOTIVATION TEACHER NOTES1. Teacher does demonstration of reaction of magnesium and oxygen; have students describe what

happens and they tell that compounds are formed. Students draw Lewis Dot diagrams for magnesium and for oxygen, and explain what will happen. Students have background on the elements and know

Lab: Conductivity Of Covalent And Ionic Compounds attached on

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MOTIVATION TEACHER NOTEScharges of the different groups from their Periodic Table diagrams done in Unit. Review electron configuration from Unit 3.

2. Students set personal and academic goals

3. Preview the Authentic Assessment so students know what is expected by the end of the Unit

pages 4-7: do not do molten materials; give students answers for these, as these are potentially dangerous.

TEACHING-LEARNING (Holt Chemistry pages 158-207) TEACHER NOTES1. Teacher explains types of bonds to students. Ionic and Covalent

In previous chapter, we discussed electronegativity and bonding strength; sharing of electrons (covalent) and giving up of electrons (ionic). Students refer back to the work in the Periodic Table unit and discuss how groups react with each other. (IVA, IVB)

2. Teacher shows students examples of ionic and covalent bonds so they see how elements combine, and students use Periodic Table diagrams and information from previous discussion to determine if bonds formed are ionic or covalent. (IVA, IVB)Students read article on Types of Bonding (attached) or a PowerPoint to analyze how the text structures information into categories to help the reader process the information. (RST.5)

3. Teacher does lecture on polyatomic ions; students take notes for future reference on compounds. They need to determine meaning of polyatomic ions and diatomics - - ask students to use what they know from the structure of the word to determine how to write the formula and what it means. The key is to have students distinguish those that have charges from those that do not. This will be used in writing equations and balancing equations. Teacher introduces suffixes: -ide, -ate, -ite; in addition, mention some prefixes as well. Discuss the Roman Numerals / or prefixes that indicate the charge for the transition elements (ions ) (IVA, IVB; IVD, IV E)

4. Use Ball-Stick Lab (VSEPR) to reinforce ionic and covalent bonds and introduce double and triple bonding. This lab includes Lewis Dot Structures. (Note: this takes 2-3 class periods). In the lab, the focus is the diatomics. (IVF, IVG)

5. Teacher discusses the concept of polarity and students can distinguish between polar and non-polar types of bonds. Students use Periodic Table and electronegativity chart to determine if polar or non-polar; the smaller the difference, the more likelihood it is polar. Discuss the naming of molecular compounds using prefixes. (IVC, IVD)

6. Define organic compounds for students and cite examples. Explain what a polymer is as well as a fossil fuel. Connect to Ball-Stick Lab. (IVE)

Formulas/Oxidation Lab (T-L #1,3)(Attached on pages 8-9)

Article attached on pages 10-11

VSEPR Lab (#4, attached on pages 12-13)

For future reference: use letters such as A, B, x, and y to introduce compounds (atoms) in a formula. Later on, substitute A’s etc with chemical symbols.

TRADITIONAL ASSESSMENT TEACHER NOTES1. Unit Test: Multiple-Choice

TEACHER ASSESSMENT TEACHER NOTES1. Lab reports or practical reports, using rubrics for quality points.2. Assignments/worksheets3. 2- 4-point questions

AUTHENTIC ASSESSMENT TEACHER NOTES1. Students evaluate their goals for the Unit.

2. Teacher creates 2-4 charts that follow the examples in the VSPER lab, and students conduct error analysis to determine if the information is correct. If there are errors, the students must correct the

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AUTHENTIC ASSESSMENT TEACHER NOTESchart and explain their reasoning in addition to correcting the information.

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MOTIVATION LAB: Conductivity of Covalent and Ionic Compounds

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T-L #1 and 3: Formulas and Oxidation Numbers

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T-L #2

Types of Chemical BondAlthough there are only two main ways for atoms to form a molecule, there are several variations. Ionic bonds, polar bonds, dative bonds and hydrogen bonds are explained.

By Martin Bell on Apr 28, 2009

A chemical molecule is formed when two or more atoms join together. They join either when one or more atoms "donates" electrons to the other(s), in a process called ionic bonding, or when they share electrons, to form a covalent bond. For an explanation of what electrons and atoms are, the article Structure of the Atom is good background.

Ionic BondingThis type of molecular bond happens when an atom, or group of atoms, "donates" one or more electrons to another atom, or group of atoms. An atom is electrically neutral, but when an atom loses one or more electrons, it is positively charged. It is then called an "ion".

An example of ionic bonding is Sodium Chloride, or table salt. Sodium has one spare electron in the outer shell, and Chlorine has an outer shell that needs one electron to complete it. They can therefore react to form an ionic compound. Another example is Potassium Iodide, that is used to dissolve gold.

Covalent BondingA covalent bond is formed when one or more atoms share electrons so that they can each end up with completed outer shells. There are several different types of covalent bond.

Non-Polar Covalent BondingThis type of chemical bond happens when two atoms from the same element share electrons. Hydrogen gas, for example, is made from molecules that are formed from pairs of Hydrogen atoms. Each hydrogen atom has one electron, but needs two electrons to complete the outer shell. Since each atom has the same "pull" on the electrons, the covalent bond is not biased towards any of the atoms. It is therefore non-polar.

Polar Covalent BondingThis type of chemical bond happens when atoms share electrons, but one of the atoms takes a larger "share" of the electrons. Hydrogen Chloride molecules are made from one atom each of Hydrogen and Chlorine. Each atom shares one electron with the other. It is polar, because the

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Chlorine "uses" the two shared electrons more than the Hydrogen does. Most molecules are at least slightly polar.

Dative Bond (aka Coordinate Covalent Bond)This type of chemical bond is formed when the shared electrons are all provided by one of the atoms in the molecule. A good example is the Ammonium ion. Nitrogen has five electrons in the outer shell, and Hydrogen has one. Ammonia is formed when three Hydrogen atoms combine with one Nitrogen atom to form a molecule. There are therefore three pairs of shared electrons plus one pair of electrons provided solely by the Nitrogen. In a solution of water, however, a Hydrogen ion can "tag" onto the pair of electrons provided by the Nitrogen, to form the Ammonium (NH4+) ion. (Note that Ammonium is Ammonia [NH3] plus Water [H2O] giving NH4OH, and the ions from it are NH4+ and OH-).

Hydrogen BondThis type of bond is formed when the polar (positive) Hydrogen atom in a molecule is attracted to the slightly polar (negative) atom in a molecule. A good example of this is water, H2O. Two Hydrogen atoms each share an electron with Oxygen, which needs two electrons to complete the outer shell. Since the Hydrogen is slightly positive, because it gets a smaller share of the electrons, it is attracted to the slightly negative side of the Oxygen atom, even though it is part of a different molecule.

Summary of Chemical Bond TypesThere are two main types of chemical bond, ionic and covalent. They can all be considered to be a sharing of electrons for the purpose of giving each atom an outer electron shell that is complete. The amount of electron sharing is what defines the type of bond.

Copyright Martin BellMartin BellM

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T-L #4 Shapes and Polarities of Covalent Molecules

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