Chemistry CPA Unit 4 Notes: Compounds and Nomenclature West Essex Regional High School 2013-2014 Callahan, Pengitore & Ricafort.

Chemistry CPA Unit 4 Notes:

Compounds and Nomenclature

West Essex Regional High School2013-2014

Callahan, Pengitore & Ricafort

NJCCCS & Common Core

• NJCCCS - 5.2.12.B.1:• An atom’s electron configuration, particularly of the outermost electrons, determines how

the atom interacts with other atoms. Chemical bonds are the interactions between atoms that hold them together in molecules or between oppositely charged ions.

• Model how the outermost electrons determine the reactivity of elements and the nature of the chemical bonds they tend to form.

• Common Core LLA: • CCSS.ELA-Literacy.RST.11-12.4: Determine the meaning of symbols, key terms, and other

domain-specific words and phrases as they are used in a specific scientific or technical context relevant to grades 11–12 texts and topics.

• CCSS.ELA-Literacy.RST.11-12.5: Analyze how the text structures information or ideas into categories or hierarchies, demonstrating understanding of the information or ideas.

• CCSS.ELA-Literacy.RST.11-12.9: Synthesize information from a range of sources (e.g., texts, experiments, simulations) into a coherent understanding of a process, phenomenon, or concept, resolving conflicting information when possible.

Unit Objectives:

Chapter 4• Distinguish the properties of compounds

from those of the elements of which they are composed.

• Compare and contrast the properties of sodium chloride, water, and carbon dioxide

• Model the two types of compound formation, ionic and covalent, at the atomic level

• Demonstrate how and why atoms achieve chemical stability by bonding

• Compare, using examples, the effect of covalent and ionic bondings on the physical properties of compounds

Chapter 5• Apply ionic charge to writing formulas for

ionic compounds.• Apply formulas to name ionic compounds• Interpret the information in a chemical

formula• Compare the properties of covalent and

ionic substances.• Distinguish among allotropes of an

element• Apply formulas to name covalent

compounds.

Formation of Compounds

Chapter 4

Element Properties vs. Compounds Properties: What’s the difference?

Sodium and Chlorine• Sodium as an element (Na) –• Shiny, white, soft, solid metal• Melting point - 98°C• Extremely reactive with water and

air!

• Chlorine as an element (Cl)• Pale green, poisonous gas with

choking odor and kills living cells• Extremely hazardous to society

Sodium Chloride (NaCl)• Two dangerous elements combine

to form a safe substance we use each day!• Tiny white crystals (which are

brittle)• Melting point of 800°C!• Not a conductor• Used as table salt, in recipes and as

a food preservative• Natural part of the human diet

Sodium Chlorine Sodium Chloride

Element Properties vs. Compounds Properties: What’s the difference? • Carbon and Oxygen• Carbon as an element (C)

• Nonreactive at room temp• Can be in forms of charcoal, diamonds

and graphite

• Oxygen as an element (O)• Colorless, odorless, tasteless gas • Humans need it to breath• Rusting is due to reaction with oxygen

• Carbon Dioxide (CO2)• Colorless, odorless gas at room

temperature• More dense than air• When cooled below -80°C it goes from a

gas right to a white solid• Can make Carbon Dioxide simply by

burning carbon in air• Used in photosynthesis• Application and Critical thinking -

• What do power plants use to create energy?

• How does the burning of that substance produce carbon dioxide?

• Why do you think an abundance of carbon dioxide is bad for our atmosphere?

Carbon Oxygen Carbon Dioxide (CO2)

Element Properties vs. Compounds Properties: What’s the difference? • Hydrogen and Oxygen• Hydrogen (H) as an element• Colorless, odorless, tasteless gas• Reactive and reacts vigorously

with other elements

• Oxygen (O) – we learned about that above.

• Water (H2O)• Universal solvent• Important everywhere – from

rivers from blood • Only one of three substances that

occurs naturally in the environment in all three states of matter (ice, water, vapor)• Important component of nearly all

biochemical reactions

Hydrogen Oxygen Water

Chemical Bonds

Why and how do you suppose elements are mostly found in compounds and not alone?• Think about their valence electrons! And quietly answers in the space

provided.

Electrons Review

• Atomic number = number of Electrons• Electrons vary in the amount of energy they possess, and they

occur at certain energy levels or electron shells• Electron shells determine how an atom behaves when it

encounters other atoms• The first shell wants a maximum of 2 electrons, and all others

want a maximum of 8 electrons. • Valence shell filling is the ultimate goal of ALL atoms. • They bond and react IN ORDER to fill their valence shell.

Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons

C would like to N would like toO would like to

Gain 4 electronsGain 3 electronsGain 2 electrons

Why are electrons important?

• Elements have different electron configurations• Different electron configurations mean different levels of bonding

Take a look at the diagram and answer the following questions:

1. Review: A. X would be the electron dot formula for

1) Na 2) K 3) Al

B. X would be the electron dot formula

1) B 2) N 3) P 2. Exercise – draw the Lewis dot structures for the first 18 elements on the periodic

table.3. What elements do you see that could “hook up” with one another to create a

“partnered” 8-valence electron shell?

Electron Dot Structures

Symbols of atoms with dots to represent the valence-shell electrons

1 2 13 14 15 16 17 18

H He:

Li Be B C N O : F :Ne :

Na Mg Al Si P S :Cl :Ar :

Atoms form partnerships by making bonds1. Atoms share or exchange their electrons with

another atom or atoms in order to share a completed valence shell.

2. When they “hook up”, it’s called a bond.3. There are two types of bonds:

1. Ionic2. Covalent

Properties of Ionic Compounds

• Hard solids that have a crystal appearance and structure at room temperatures • Are referred to as “salts”• Ions are held together in very

organized and tight/strong bonds which take an enormous amount of energy to break• Soluble in water• Electrolytes – conduct electricity

when dissolved in water

Ionic Bonds

• bond formed between two ions by the transfer of electrons• Ionic compounds form when metals bond to nonmetals.•Metals loose or give their electrons away to match the

number of valence electrons of their nearest noble gas, forming cations• Nonmetals gain or take electrons from a metals to match

the number of valence electrons of their nearest noble gas forming anions

Metals Loose, Nonmetals Gain

Sodium Loosing Chlorine Gaining

More on Metals Loosing…

Positive ions form when the number of electrons are less than the number of protons

Group 1 metals ion 1+

Group 2 metals ion 2+

• Group 13 metals ion 3+

Formation of Sodium Ion

Sodium atom Sodium ion Na – e Na +

1st shell: 2 1st shell: 22nd shell: 8 2nd shell: 83rd shell: 1 ( = Ne’s configuration!)

(2-8-1) (2-8) 11 p+ 11 p+

11 e- 10 e-

0 1+

Formation of Magnesium Ion

Magnesium atom Magnesium ion

Mg – 2e Mg2+

1st shell: 2 1st shell: 22nd shell: 8 2nd shell: 83rd shell: 2 ( = Ne’s configuration!)

(2-8-2) (2-8)

12 p+ 12 p+

12 e- 10 e-

0 2+

Some Typical Ions with Positive Charges (Cations)

Group 1 Group 2 Group 13

H+ Mg2+ Al3+

Li+ Ca2+

Na+ Sr2+

K+ Ba2+

Learning Check

A. Number of valence electrons in aluminum1) 1 e- 2) 2 e- 3) 3 e-

B. Change in electrons for Al’s octet1) lose 3e- 2) gain 3 e- 3) gain 5 e-

C. Ionic charge of aluminum 1) 3- 2) 5- 3) 3+

Solution

A. Number of valence electrons in aluminum3) 3 e-

B. Change in electrons for octet1) lose 3e-

C. Ionic charge of aluminum 3) 3+

Learning Check

Give the ionic charge for each of the following:A. 12 p+ and 10 e-

1) 0 2) 2+ 3) 2-

B. 50p+ and 46 e-1) 2+ 2) 4+ 3) 4-

C. 15 p+ and 18e-2) 3+ 2) 3- 3) 5-

More on Nonmetals Gaining…

In ionic compounds, nonmetals in 15, 16, and 17 gain electrons

from metals

Nonmetals add electrons to achieve the octet arrangement

Nonmetal ionic charge:

3-, 2-, or 1-

Fluoride Ion

unpaired electron octet 1 -

: F + e : F :

1st shell: 2 1st shell: 22nd shell: 7 2nd shell: 8(2-8-1) ( = Ne’s configuration!)

(2-8)

9 p+ 9 p+

9 e- 10 e- 0 1 -

ionic charge

Ions happen because of bonding

• Ionic Bond:•Between atoms of metals and nonmetals with

very different electronegativity•Bond formed by transfer of electrons•Produce charged ions all states. •Conductors•Have high melting point.•Examples; NaCl, CaCl2, K2O

Ionic bond – electron from Na is transferred to Cl, this causes a charge imbalance in each atom. The Na becomes (Na+) and the Cl becomes (Cl-), charged particles or ions.

Practice – Predict the ion that will form with each element listed below. Show your work!!!• 1. Ca

• 2. P

• 3. S

• 4. K

• 5. Br

Properties of Covalent Compounds• Composed of molecules held together by strong forces called

covalent bonds which aren’t based on charge.• Molecules are held together by intermolecular forces which are

weaker than the force that hold ions together.• Tend to be liquids or gases at room temperature.• Not conductors of electricity• Don’t usually dissolve in water

Covalent Bond

•bond formed by the sharing of electrons•Between nonmetallic elements of similar

electronegativity.• Formed by sharing electron pairs• Stable non-ionizing particles, they are not conductors

at any state• Examples; O2, CO2, C2H6, H2O, SiC

There are Two Types of Covalent Bonds…•Nonpolar Covalent•Polar Covalent

when electrons are shared equally

NONPOLAR COVALENT BONDS

H2 or Cl2

Oxygen AtomOxygen Atom Oxygen AtomOxygen Atom

Oxygen Molecule (O2)

O2 is an example of a nonpolar covalent bond

when electrons are shared unequally

POLAR COVALENT BONDS

H2O

- water is a polar molecule because oxygen is more electronegative than hydrogen, and therefore electrons are pulled closer to oxygen.

Practice: Tell whether the examples below are elements, ionic compounds or covalent compounds.1. Potassium (K)

2. Lithium fluoride (LiF)

3. Carbon dioxide (CO2)

4. Oxygen gas (O2)

5. Cobalt (Co)

Writing Formulas and Naming Compounds

Chapter 5

Naming a Binary Ionic CompoundA binary compound is one in which contains only two elements. To name a binary compound,• identify the cation and anion.• name the cation first• name of the anion second, but change the ending to “-ide”

Examples: Sodium + Chlorine = Sodium ChlorideMagnesium + Oxygen = Magnesium Oxide

47

Complete the names of the following ions. Ba2+ Al3+ K+

_________ __________ _________

N3 O2 F

_________ __________ _________

P3 S2 Cl _________ __________ _________

Learning Check

Practice – Naming Binary Ionic Compounds1. Lithium + Nitrogen2. KCl3. Strontium + Selenium4. MgCl2

5. Calcium + Chlorine6. Al2O3

Writing Formulas for Binary Ionic Compounds

1. Write the symbol for the metal first with the charge• Example: Magnesium, Mg2+

2. Write the symbol for the nonmetal next with the charge• Example: Chlorine, Cl 1-

3. Crisscross the number of the charge (don’t write a number if the charge is -1 or +1)• Example: Mg2+ Cl 1-

MgCl2• All compounds are neutral, so the charges must add to ZERO:

1(+2) + 2(-1) = 2 – 2 = 0

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Charges of Representative Elements

Copyright © 2005 by Pearson Education, Inc.Publishing as Benjamin Cummings

Names of Some Common Ions

Learning CheckWrite the formulas and names for compounds of the following ions:

Br− S2− N3−

Na+

Al3+

EXAMPLES

Different Charges:

1. Aluminum sulfideAl+3 S-2

Al2S3

2. Calcium chlorideCa+2 Cl-1

CaCl2

Equal but opposite charges:

3. Magnesium oxide

Mg+2 and O-2

Mg2O2 this can be reduced to

MgO

Practice – forming binary ionic compounds

Calcium and Oxygen

Aluminum and Fluorine

Boron and Oxygen

Strontium and Nitrogen

Barium and Selenium

Ions with charges

Ca 2+ O2-

Criss-cross and drop Charge

Formula:

Ca2O2

Reduces to 0:

CaOName:

Naming when the metal forms more than one chargeLook at the Periodic Table – some elements have more than one charge –

Transition Metals Ex: Copper +1 or +2

• Roman Numerals are used to indicate the charge. Copper (I) or Copper (II)

Cu+1 or Cu+2

• Example: Copper (Cu+2) and Chlorine (Cl1-)• Writing the name: Copper (II) chloride• Writing the formula: CuCl2

Common Roman NumeralsNumber Roman Numeral1 I2 II3 III4 IV5 V6 VI7 VII8 VIII9 IX10 X

Naming compounds that have metals with multiple charges – THE TRICK… • Determine the charge by working backwards•Write the charge in roman numerals in the name

CuF2• Copper is either +1 or +2 charge• In this case it is +2 since there are two Fluorine atoms

for every one copper (F is always -1 charge)• Copper (II) Fluoride

Practice – write the formula and name

Chromium (2+) and Chlorine

Lead (2+) and Oxygen

Manganese (3+) and iodine

Iron (3+) and Oxygen

Write the ions with their charges

Criss-Cross and drop the charge –Formula

Name

Practice – Predict the charge & formula from the formula

Iron (III) Chloride Lead (IV) Fluoride Nickel (III) Bromide Mercury (II) oxide

Write the Ions Cl 1-

Criss- cross and drop chargeFormula

Polyatomic Ions

•What are they?•An ion that has two or more different elements •The ion is a group of atoms held together by covalent bonds. •The group as a whole has a charge, so it acts just like an anion, which the exception of the Ammonium (NH4)+ ion

How To Handle Polyatomic Ions…•Always include parenthesis around these ions• End in –ate or –ite• Exceptions – Hydroxide, Cyanide, Ammonium

• Found on the back of your periodic table!

Common Polyatomic Ions

Naming Compounds with Polyatomic Ions•Metal bonded to a polyatomic ion

Al2(SO4)3

1.Name the metal2.Name the polyatomic ion as it appears on the back

of your periodic table

Examples

MgSO4

CaCO3

Sn(OH)4

Writing Formulas for Compounds with Polyatomic Ions1. Write the symbol for the metal and charge2. Write the polyatomic ion in parenthesis and with

charge outside3. Criss-cross the charges

Practice making formulas for compounds with polyatomic ions

Magnesium Hydroxide Sodium Sulfate Calcium Carbonate Aluminum Sulfite

Write the Ions with their charges – put polyatomics in parenthesis with charge outside!!

Mg2+ (OH)-

Criss-cross and drop charge outside parenthesisFormula

Mg(OH)2

Naming Molecular (Covalent) Compounds

• Two non-metals bonded together; shared bond of electrons

Example: CO2 = carbon dioxide•Prefixes are used to express the number of each

element• The second nonmetal ends in –ide•Never reduce!!

PrefixesNumber Prefix1 mono-2 di-3 tri-4 tetra-5 penta-6 hexa-7 hepta-8 octa-9 nona-10 deca-

ATTENTION!!!• The prefix mono- is not used with the first

named element• Use the back of your periodic table to help

you

Practice Naming Covalent/Molecular CompoundsCompound SO3 N2O5 CO C2Br6

Name

Practice Writing Formulas for Covalent/Molecular Compounds

Name pentacarbon decahydride tetrasulfur heptoxide carbon monobromide Iodine trichloride

Compound

Naming and Writing Formulas for Hydrocarbons• Compounds containing Carbon are organic compounds• Hydrocarbon is an organic compound that contains only Carbon (C)

and Hydrogen (H)• Hydrocarbons occur naturally as fossil fuels such as coal, natural gas,

and petroleum• All carbon atoms can form 4 covalent bonds.

Table 5.8 (p.180) HydrocarbonsFormula NameCH4 methane

C2H6 ethane

C3H8 propane

C4H10 butane

C5H12 pentane

C6H14 hexane

C7H16 heptane

C8H18 octane

C9H20 nonane

C10H22 decane