UNIT 2 CHAPTER 20 CHEMICAL BONDS OCTOBER 5-9, 12-16, 2015

UNIT 2CHAPTER 20

CHEMICAL BONDSOCTOBER 5-9, 12-16, 2015

DO NOW:

1. Review “Composition of Matter” in your interactive notebook.

2. List 4 compounds that you already know.

HOMEWORK

DUE Friday, October 9: Science Fair Research Paper, Bibliography

Bring your textbook Wednesday!!

GEORGIA PERFORMANCE STANDARDS

SPS1. Students will investigate our current understanding of the atom.

b. Compare and contrast ionic and covalent bonds in terms of electron movement.

THE BIG IDEA: TYPES OF CHEMICAL BONDS

ESSENTIAL QUESTION:WHY DO ATOMS FORM CHEMICAL

BONDS?

TYPES OF CHEMICAL BONDS

Compound—substances made of the combined atoms of two or more elements.

Chemical formula—tells what elements a compound contains and the exact number of the atoms of those elements.


Some Common Compounds

Vinegar Acetic acid HC2H3O2

Sand Silicon dioxide SiO2

Stomach Acid

Hydrochloric acid

HCl

Cane Sugar Sucrose C12H22O8


Coefficient-Represents the #of units of each substance

2H2O

Subscript—represents # of atoms in a molecule of a particular element

SO42-

Superscript—represents oxidation # or how many electrons have been gained or lost.


Atoms form compounds to become chemically stable. An atom is chemically stable when the outer energy level or valence shell is complete or full.

Chemical bond—force that holds together the atoms in a substance.


Ionic Bond vs. Covalent Bonds

*loses or gains electrons

* Shares electrons

*attraction between opposite charges of ions

*can form multiple bonds

*between metal & nonmetals

Between a nonmetal and a nonmetal

** ION—positive or negatively charged atoms

DO NOW:Chapter 20 Vocabulary:

1. Chemical bond2. Chemical

formula3. Ionic bond4. Covalent bond5. Molecule

See Pg. 626

6. Polar molecule7. Nonpolar molecule8. Oxidation number9. Polyatomic ion10. Ion




THE BIG IDEA: ATOMIC BONDING

ESSENTIAL QUESTION:WHAT IS AN ION?

ATOMIC BONDS

An atom that has lost or gained electrons is called an ion.

Ions are charged particles because it now has either more or fewer electrons than protons.

ATOMIC BONDS

Ionic bonding occurs when an electron is donated.

loss of electron + called a cation

gain of electron - called an anion

ATOMIC BONDSCovalent Bonding occurs when electrons are shared.

1. Single covalent bonds—2 shared electrons

2. Multiple covalent bonds—more than 1 pair of electrons.

3. Unequal sharing

polar bonds=unequal sharing, slightly +

nonpolar bonds=equal sharing

Watch video: Chemistry Basics Part 2

DO NOW:

•COMPLETE THE QUIZ (OPEN NOTE)




THE BIG IDEA: WRITING FORMULAS AND NAMING

COMPOUNDS

ESSENTIAL QUESTION:WHAT WOULD A CHEMIST NAME THE

COMPOUND CaCl?

WRITING FORMULAS AND NAMING COMPOUNDS

Binary compound—compound composed of 2 elements

Oxidation number—positive or negative number (on PT) which indicates how many electrons an element has gained, lost or shared when bonding with another atom.


When writing formulas for binary ionic compounds, it is important to remember that compounds formed have a net charge of zero.


When writing formulas for binary ionic compounds, it is important to remember that compounds formed have a net charge of zero.


Polyatomic ions—a positively or negatively charged covalently bonded group of atoms.

The prefix poly—means “many” so the term polyatomic means “having many atoms.”

POLYATOMIC IONSCHARG

ENAME FORMULA

1+ AMMONIUM NH4+

1- ACETATE C2H3O2-

1- CHLORATE ClO3-

1-HYDROXID

EOH-

1- NITRATE NO3-

2-CARBONAT

ECO3

2-

2- SULFATE SO42-

3-PHOSPHAT

EPO4

3-


Hydrate—a compound that has water chemically attached to its ions and written into its chemical formula.

Covalent compounds can form more than one compound with each other. Scientists use Greek prefixes to indicate # of atoms of each element in binary compounds.


PREFIXES FOR BINARY COVALENT COMPOUNDS

# ATOMS

1 2 3 4 5 6 7 8

PREFIXMONO

-DI-

TRI-

TETRA-

PENTA-

HEXA-

HEPTA-

OCTA

WRITING FORMULAS

•STEP 1: Write the symbol of the element or the polyatomic ion that has the positive oxidation number.

•STEP 2: Write the symbol of the element of the polyatomic ion with the negative oxidation number

•STEP 3: Add subscripts so that the sum of oxidation numbers of all atoms in the formula is zero—use the criss-cross method: the charge (without the sign) of one ion becomes the subscript of the other ion.

NAMING COMPOUNDS•STEP 1: Write the name of the first element. (Subscripts do not become part of the name for the ionic compound but are used to determine prefixes when naming covalent compounds.)

•STEP 2: Write the root of the name of the second element. EX: Chlorine root is chlor-; oxygen root is ox-; bromine root is brom-

•STEP 3: Add the ending –ide to the root. Ex:

(Ionic) BaF2—Barium Fluoride, AlCl3—Aluminum

Chloride; (Covalent) N2O—Dinitrogen Monoxide,

CO—Carbon Monoxide

DO NOW:

1. WHICH OF THESE ELEMENTS CONTAINS FOUR VALENCE ELECTRONS? A. HELIUM B. BERYLLIUM C. CARBON D. OXYGEN




THE BIG IDEA: BONDING RULES/CHEMICAL

STRUCTURE

ESSENTIAL QUESTION:WHAT DOES “ENDS AND BENDS”

MEAN?

BONDING RULES/CHEMICAL STRUCTURE

Hydrogen H—

Carbon —C

—

Nitrogen —N—

Oxygen —O

—

How many carbons?

Code# of

carbons

Examples

Meth- 1Methane (CH4)

Eth- 2 Ethane (C2H6)

Prop- 3Propane (C3H8)

But- 4Butane (C4H12)

Pent- 5Pentane (C5H12)

Hex- 6Hexane (C6H14)

BONDING RULES/CHEMICAL STRUCTURE

Types of Carbon-Carbon BondsCode Means-ane Only carbon-carbon single bonds

-eneContain a carbon-carbon double

bondRule 1: Carbon lives on ends and bendsRule 2: Hydrogens bring carbon happinessWatch video: Making Sense of Chemical Structures




THE BIG IDEA: REVIEW MAIN IDEAS OF CHAPTER 20

CHAPTER 20 REVIEW

•ON A SEPARATE SHEET OF PAPER COMPLETE QUESTIONS #1-32

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UNIT 2 CHAPTER 20 CHEMICAL BONDS OCTOBER 5-9, 12-16, 2015