Unit 3: Ionic and Molecular Compounds Name Block · Unit 3: Ionic and Molecular Compounds Name _ Block _ Learning Goals Your Prior Understanding of Learning Goals ... Transitions

Unit 3: Ionic and Molecular Compounds Name __________________________________________ Block _____

Learning Goals Your Prior Understanding of Learning Goals Excellent

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Okay

Poor

A. Describe how chemical bonds can form between atoms.

B. Write the symbols for the simple ions of the representative elements.

C. Using charge balance, write the correct formula for an ionic compound.

D. Given the formula of an ionic compound, write the correct name; given the name of an ionic compound, write the correct formula.

E. Write the name and formula for an ionic compound containing a polyatomic ion.

F. Given the formula of a molecular compound, write its correct name; given the name of a molecular compound, write its formula.

G. Draw the Lewis dot formulas for molecular compounds with multiple bonds.

H. Predict the three-dimensional structure of a molecule and classify it as polar or nonpolar.

I. Use electronegativity to determine the polarity of a bond or a molecule.

Set an appropriate academic goal for yourself and your learning for this unit by responding to the following questions.

a. What would you like to achieve academically by studying this unit?

I want to ______________________________________________________________________________________

_____________________________________________________________________________________________.

b. How will you know that you have met this academic goal?

I will have met my goal when ______________________________________________________________________

_____________________________________________________________________________________________.

c. What are two specific strategies/activities you plan on using or doing in order for you to achieve your goal?

In order to achieve my academic goal, I will __________________________________________________________

_____________________________________________________________________________________________

_____________________________________________________________________________________________.

d. Why is this goal important to you?

This goal is important to me because _______________________________________________________________

_____________________________________________________________________________________________.

e. What is the deadline for reaching this goal?

I will achieve my goal by _________________________________________________________________________.

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Chemical Bonds

Learning Goal: Describe how chemical bonds can form between atoms.

QUESTIONS:

Electrons in the outermost shell of any atom give that atom its chemical properties,

including its ability to form ___________________________________.

• The important outermost electrons are called _______________ electrons; the

shell they occupy is called that atom’s _________________________________.

• __________ valence electrons are relatively stable and are referred to as

_________________________ pairs.

• __________ electrons strongly tend to bond by pairing up with an electron from

another atom.

Chemical bonds forms in either one of two ways:

• when one atom __________ an unpaired electron to another atom which also

has an unpaired valence electron; this is known as an _______________ bond.

• when two atoms, both of which have an unpaired electrons, __________ their

valence electrons to form a single shared valence pair; this is known as a

_______________ bond.

SUMMARY: 34

Ions

Learning Goal: Write the symbols for the simple ions of the representative elements.

QUESTIONS:

When the number of protons in an atomic nucleus __________ the number of

surrounding electrons in that atom, the charges balance and the atom is electrically

_______________.

• If one or more _________________________ are lost or gained, the balance is

upset and the atom then has a net electric charge.

• Any atom that has a net electric charge is called an _____.

- Positive ions are formed when a neutral atom

__________ electrons; these positive ions are

known as __________.

- Negative ions are formed when a neutral atom

__________ electrons; these negative ions are

known as __________.

• Chemists use a ____________________ to the right of the atomic symbol to

show the magnitude and sign of an ion’s charge.

• Usually the numeral 1 is __________ when indicating either a 1+ or 1- charge.

• Atoms tend to lose or gain electrons so that they end up with an outermost

occupied shell that is _______________________________________________.

SUMMARY:

35

Ions

Learning Goal: Write the symbols for the simple ions of the representative elements.

QUESTIONS:

The attraction that an atom’s nucleus has for its valence electrons is weakest for

__________ atoms and strongest for __________ atoms. Therefore,

• _______________ lose their electrons easily and form cations.

• _______________ gain electrons easily and form anions.

• _________________________ tend to not form an ion as they pull strongly on

their valence electrons and they have a full valence shell. Transitions metals tend to form _______________ ions, but the number of electrons lost

tends to __________. The positive charge of any ion formed from an atom of a transition

metal is equal to the number of electrons lost.

SUMMARY: 36

Ionic Compound Formulas

Learning Goal: Using charge balance, write the correct formula for an ionic compound.

QUESTIONS:

When an atom that tends to __________ electrons comes in contact

with an atom that tends to __________ them, an electron

_______________ occurs.

• The result of the transfer is that two ___________________

charged ions are formed.

• The two oppositely charged ions are then attracted to each

other by ______________________________, which holds

them close together.

• This electric force of attraction between oppositely charged

ions is called an ____________________.

• An ionic bond typically forms between __________ cations

and _______________ anions. All chemical compounds that contain ions are known as __________________________.

• FOR ALL IONIC COMPOUNDS, POSITIVE AND NEGATIVE CHARGES MUST BALANCE!

• The chemical formula of a compound represents the _______________ and

____________________ in the lowest whole-number ratio of the atoms or ions.

- The ____________________ in the chemical formula for an ionic

compound indicate the number of _______________________________

needed to create a compound with an overall _____ charge.

- When there is no subscript for a symbol in a formula, it is assumed to be

_____.

- The group of ions that contains the lowest ratio of ions in an ionic

compound that will achieve a zero charge is called a

_________________________.

SUMMARY:

37



QUESTIONS:

Use the following steps to write the chemical formula for an ionic compound using charge

balance.

Guide for Writing Chemical Formulas for Ionic Compounds

Example: lithium and nitrogen

Another method for writing the chemical formula for an ionic compound is known as the

____________________ method.

1. Determine the ionic charges of the elements in the ionic compound.

2. Write the number of the charge for the __________ as the subscript for the

__________ element symbol.

3. Write the number of the charge for the __________ as the subscript for the

__________ element symbol.

4. Reduce the subscripts if necessary to obtain the _________________________

______________________________.

SUMMARY: 38



QUESTIONS:

The formation of ionic compounds can be diagrammed using Lewis dot diagrams.

1. Determine how many ________________________________________ are

required for the ionic compound.

2. Draw a Lewis dot diagram for _______________ of the element that will form

__________.

3. Draw a Lewis dot diagram for _______________ of the element that will form

__________.

4. Draw arrows between the diagrams to show the __________________________

that occurs.

5. Write an arrow, to indicate ___________________________________, followed

by the newly formed ions, including _______________.

sodium chloride, NaCl

magnesium chloride, MgCl2

Diagram the formation of the ionic compounds that result between the following pairs of elements. Include the chemical formula for the final ionic compound as well.

SUMMARY:

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Naming Ionic Compounds

Learning Goal: Given the formula of an ionic compound, write the correct name; given the name of an ionic compound, write the correct formula.

QUESTIONS:

The name of a binary ionic compound, made of two types of ions, has two components:

• the name of the __________ is written first; this

name is the same as the cation’s ___________

______________;

• the name of the __________ is written second;

this name is the _________________________

of the anion’s elemental name followed by the

suffix __________;

• a __________ separates the name of the cations and anions.

Cation Cation Name Anion Anion Name

Al3+ Br-

Ca2+ Cl-

Ge3+ I-

K+ N3-

Li+ O2-

Mg2+ P3-

Na+ S2- Name the following ionic compounds using the provided chemical formulas.

CaCl2

NaI

K3N

Al2O3

SUMMARY: 40



QUESTIONS:

Transition elements and representative metals of groups 4A and 5A can lose electrons

from their valence shell and a lower energy level. Therefore, atoms of these elements

• can form _______________ positively charged ions;

• are described as having a __________ charge that cannot be predicted from the

periodic table;

• require a __________________________________________________ after

their name to indicate the specific charge on the ion.

Name the following ionic compounds using the provided ions or chemical formula.

Cu2+ and S2-

Mn3+ and F-

SnO2

Fe3P2

SUMMARY:

41



QUESTIONS:

The name of an ionic compound can be used to write its chemical formula by following

these steps:

1. Write the _______________ of the elements that form the ionic compound.

2. Determine the __________ of the cation and anion.

a. If the cation has a _________________________ after it, that is the

charge on that ion.

b. If there is no Roman numeral, you can determine the charge from the

cation’s position on the ______________________________.

c. Determine the charge of the __________ by its position on the periodic

table.

3. Determine how many of each cation and anion are

needed to make the compound _______________. The

__________________ method can be used for this step.

4. Write the symbols of each element together and add in

the appropriate ____________________ indicating the

number of each ion needed for the neutral compound. Determine the chemical formula of the following ionic compounds.

magnesium sulfide

iron(II) oxide

calcium fluoride

aluminum phosphide

lead(IV) bromide

SUMMARY: 42

Polyatomic Ions

Learning Goal: Write the name and formula for an ionic compound containing a polyatomic ion.

QUESTIONS:

A polyatomic ion is a group of ________________________________________ that has

an overall ionic charge.

• Most polyatomic ions consist of

_______________ such as phosphorus,

sulfur, carbon, or nitrogen covalently

bonded to oxygen atoms

• Almost all the polyatomic ions are

__________ with charges of _____,

_____ or _____.

• Only one common polyatomic ion,

__________, has a __________ charge.

• The names of the most common

negatively charged polyatomic ions end

in _____or _____ with the exception of

OH- and CN-.

• The bonding between polyatomic ions

and other ions is one of

______________ attraction.

SUMMARY:

43

Polyatomic Ions

Learning Goal: Write the name and formula for an ionic compound containing a polyatomic ion.

QUESTIONS:

To write correct formulas for compounds containing polyatomic ions, follow the same

rules of ___________________________________ used for writing the formulas of

simple ionic compounds.

• The total negative and positive charges must equal __________.

• When more than one polyatomic ion is needed for charge balance,

____________________ are used to enclose the formula of the ion; a subscript

is written _______________________________________________________ of

the polyatomic ion to indicate the number needed for charge balance. When naming ionic compound containing

polyatomic ions, write the positive ion, usually

a __________, first and then write the name

of the ______________________________.

In each of the following ionic compounds, underline the polyatomic ion, write the name of the ion, determine the charge of the polyatomic ion, and indicate how many of that polyatomic ion is needed to make that compound.

K2SO4

Name: _______________

Charge: _____

# of Ions: ____

Ca(OH)2

Name: _______________

Charge: _____

# of Ions: _____

(NH4)2S

Name: _______________

Charge: _____

# of Ions: _____ Write the names and chemical formulas of the following ionic compounds that contain polyatomic ions.

aluminum phosphate

Mg(NO2)2

lithium carbonate

sodium acetate

NH4OH

SUMMARY: 44

Molecular Compounds

Learning Goal: Given the formula of a molecular compound, write its correct name; given the name of a molecular compound, write its formula.

QUESTIONS:

Two atoms can be held together by their ______________________________________

they share in a covalent bond.

• A substance made up of atoms which are held together by covalent bonds is a

_______________ compound.

• A _______________ is any group of atoms held together by covalent bonds.

• _______________ atoms, and a few metalloids, form covalent bonds, with the

exception of the ____________________ as they typically do not form

compounds due to their full valence shells.

• The chemical formula for a covalent compound uses __________ and

_______________ just like ionic compounds.

- The subscripts indicate the ___________________________________

____________________ used to form the compound.

- Usually, the elements, except for _____, are written in order of

increasing ____________________. Provide the formulas for the following compounds.

__________

__________

__________

__________

The term “covalent” refers to the sharing of _________________________.

• _________________________ of electrons are those electrons found in a single

covalent bond.

- One electron comes from

one of the atoms taking

part in the covalent bond;

the other electron comes

from the other atom taking

part in the bond.

• _________________________ of electrons are those electrons that exist in the

valence shell of an atom but are not part of the covalent bond.

- In a nonbonding pair, both electrons come from the ________________.

- Nonbonding pairs are also known as _______________.

SUMMARY:

45

Molecular Compounds


QUESTIONS:

It is possible to have ________________________________________ shared between

two atoms in ____________________ covalent bonds.

• A ___________________________________ occurs when _____ electrons are

shared between two atoms.

- There are _________________________ of electrons in a double

covalent bond.

- A double covalent bond is abbreviated with the term __________ bond.

• A ___________________________________ occurs when _____ electrons are

shared between two atoms.

- There are _________________________ of electrons in a triple covalent

bond.

- A triple covalent bond is abbreviated with the term __________ bond.

• Multiple bonds like a _______________ covalent bond are not commonly

observed.

• A triple bond is stronger than a _______________ bond, which is stronger than a

_______________ bond. In the following diagrams, circle in blue all the single bonds, red all the double bonds, and orange all the triple bonds.

Multiple covalent bonds are frequently observed in _______________ molecules.

• Diatomic molecules contain ___________________.

• Many _______________ exist in their natural state

as diatomic molecules as this provides the atoms a

stable electron arrangement.

• The elements that are diatomic in their natural state

include ___________________________________.

SUMMARY: 46

Molecular Compounds


QUESTIONS:

The naming of a _____________________________________________ made of only

_____ types of elements involves the use of prefixes. The names need prefixes because

_____________________________________________ from the same two nonmetals.

• The first nonmetal in the compound is named by its _______________ name.

• The second nonmetal in the compound is named by using the _______________

of its elemental name with the ending changed to _____.

• _______________ that indicate two or more atoms of an element are expressed

as __________ placed in front of each name.

• The prefix mono- is omitted from the ____________________ in the name.

• When adding a prefix and the vowels __________ or __________ appear

together, the first vowel is omitted from the prefix.

Prefix # of Atoms Prefix # of Atoms 1 6 2 7 3 8 4 9 5 10

Writing a chemical formula from the name of a covalent compound is easily done by

following these two steps:

• Write the ______________________________ for each nonmetal in order as

they appear in the name.

• Convert the __________ of the names into _______________. Write either the name or chemical formula of the following covalent compounds.

N2O4

Cl2O7

SiF4

sulfur trioxide

tetraphosphorus decoxide

SUMMARY:

47

Electron Dot Formulas of Molecular Compounds

Learning Goal: Draw the Lewis dot formulas for molecular compounds with multiple bonds.

QUESTIONS:

Electron dot formulas illustrate the bonds in a molecule. Electron-dot formulas show

• the _____________________________________

___________________________ in a molecule;

• the ______________________________ of

electrons shared between atoms;

• the nonbonding or unshared (________________)

of electrons;

• the ____________________ bonded to other

atoms. The following steps are used to draw an electron dot formula for a molecule.

1. Determine how many ________________________________________ are

found in the atoms of the molecule.

2. If there is more than one type of atom in the molecule, place the __________

___________________________________ in the center of the electron dot

structure.

3. Place electrons so that _____________________________________________

_________________________ _____between each atom.

4. Place the remaining valence electrons around the atoms; check that each atom

has an __________.

5. If octets are not formed, move the electrons around to form _______________

__________ between the atoms until octets are made.

6. If needed, redraw the electrons on each atom to form _________________ pairs. Write a chemical formula for each covalent compound and draw its electron dot formula.

phosphorus trichloride

formula: __________

total # of valence e-: _____

carbon monoxide

formula: __________


oxygen gas

formula: __________


SUMMARY: 48

Electron Dot Formulas of Molecular Compounds

Learning Goal: Draw the Lewis dot formulas for molecular compounds with multiple bonds.

QUESTIONS:

Some exceptions to the octet rule in an electron dot formula include:

• hydrogen, H, only gets a ____________________;

• boron, B, has only _____ electrons around it to form bonds;

• compounds of P, S, Cl, Br, and I can have _________________________ with

_____, _____, or even _____ valence electrons around them. Draw electron dot formulas for the following compounds.

BH3 SF6 PBr5

There are variations on how to draw an electron dot formula.

• Chemists often use a straight line to represents the two electrons involved in a

covalent bond.

- __________ straight line represents a single bond.

- __________ straight lines a double bond.

- __________ straight lines a triple bond.

• In some representations, the _________________________ pairs are left out. Redraw the following electron dot formulas by replacing bonding pairs of electrons with lines and then by removing the nonbonding pairs of electrons.

Electron Dot Formula w/ All Valence e-

Electron Dot Formula w/ Lines for Bonding e-

Electron Dot Formula w/o Nonbonding e-

SUMMARY:

49

VSEPR, Molecule Shape and Polarity

Learning Goal: Predict the three-dimensional structure of a molecule and classify it as polar or nonpolar.

QUESTIONS:

The three-dimensional shape of a molecule is important to understanding how it interacts

with its surroundings.

• In the valence shell electron-pair repulsion (__________) theory, the electron

groups around an atom are arranged as far apart as possible to minimize the

____________________ between their _______________ charges.

• An electron group can be _______________ of electrons or _______________

of electrons in single or multiple bonds.

• The number of electron groups is determined by drawing the _______________

_________________________ of a molecule.

2 Electron Groups

off Central Atom

Electron Group

Structure

2 bonding electron groups

lone pair

bonding electron group

Molecular

Shape

________________

3 Electron Groups

off Central Atom

Electron Group

Structure



1 lone pair

Molecular Shape

________________

________________

________________

4 Electron Groups

off Central Atom

Electron Group

Structure



1 lone pair


2 lone pairs

Molecular Shape

________________

________________

________________

SUMMARY: 50

VSEPR, Molecule Shape, and Polarity

Learning Goal: Predict the three-dimensional structure of a molecule and classify it as polar or nonpolar.

QUESTIONS:

A chemical bond is a tug-of-war between atoms for electrons.

• If the two atoms in a covalent bond are _______________, their nuclei have the

same positive charge, and therefore, the electrons are shared ______________.

• In a covalent bond between non-identical atoms, the nuclear charges are

_______________, and the bonding electrons may be shared ______________.

• Uneven sharing of electrons may give rise to slightly positive and negative

charges on atoms; this ___________________________________ is known as

a __________.

- A bond is considered _______________ if there is no dipole.

- A bond is considered __________ if there is a dipole.

• The positive and negative ends of a dipole are indicated with the symbol _____

or _____.

• A dipole can also be represented by a crossed arrow,_________, pointing to the

_______________ side of the bond. The molecular shape can be used to predict the polarity of a molecule.

Molecular Shape Polarity Explanation

polar nonpolar

the polarity depends on the electronegativity of the bonded atoms in the molecule

polar nonpolar


polar nonpolar

the lone pairs of electrons create an uneven distribution of electrons

polar nonpolar


polar nonpolar

the lone pairs of electrons create an uneven distribution of electrons

Identify whether you think the following molecules are polar or nonpolar based on shape and dipoles.

polar nonpolar

polar nonpolar

polar nonpolar

polar nonpolar

SUMMARY:

51

Electronegativity and Polarity

Learning Goal: Use electronegativity to determine the polarity of a bond or a molecule.

QUESTIONS:

The attraction that an atom has to electrons has been measured experimentally and

quantified as the atom’s ____________________.

• The range of electronegativities runs from _____ to _____.

• The _______________ an atom’s electronegativity, the _______________ its

ability to pull electrons toward itself when bonded.

• Electronegativity is greatest for elements at the ____________________ of the

periodic table and lowest for elements at the ____________________.

Rank the following element from largest to smallest electronegativity: Al, F, Mg, Rb, S. _____ > _____ > _____ > _____ > _____

Why do the noble gases have no electronegativity values?

Electronegativity values can be used to determine the _______________ of a chemical

bond by calculating the _______________ between the electronegativity values of the

bonded atoms.

• Bonds with an electronegativity difference of _______________are considered

______________________________.

• Bonds with an electronegativity difference of _______________ are considered

______________________________.

• Bonds with an electronegativity difference _______________ are considered

__________. Determine the polarity of each of the following bonds.

SUMMARY: 52

Electronegativity and Polarity

Learning Goal: Use electronegativity to determine the polarity of a bond or a molecule.

QUESTIONS:

Recall that a _______________, and not just a __________, can be classified as polar or

nonpolar. There are two questions to answer in order to determine molecular polarity.

• What is the symmetry of the molecular shape?

- ____________________ shapes can be divided into equal parts.

Examples: _________________________________________________

- ____________________ shapes cannot be divided equally.

Examples: _________________________________________________

• Are the atoms bonded to the central atom the same or are they different?

- Same atoms form dipoles that _____________________

____________________________ by equally distributing

electrons within the bonds.

- Different atoms form dipoles that may not cancel each

other out. This is because of ______________________

_____________________ and ____________________

_______________________ within the bonds.

The polarity of the molecule depends on the combination of a molecule’s symmetry and

type of atoms.

Symmetry Type of Atoms Bonded to Central Atom Polarity

N/A Note that a molecule can have polar covalent bonds and not be a polar molecule! Determine the shapes of the following molecules by drawing their electron dot formulas. Then, decide whether the molecules are polar or nonpolar.

SUMMARY:

53

Unit 3: Ionic and Molecular Compounds

Learning Goals Your Level of Mastery of Learning Goals Excellent

Good

Okay

Poor

A. Describe how chemical bonds can form between atoms.

B. Write the symbols for the simple ions of the representative elements.

C. Using charge balance, write the correct formula for an ionic compound.

D. Given the formula of an ionic compound, write the correct name; given the name of an ionic compound, write the correct formula.

E. Write the name and formula for an ionic compound containing a polyatomic ion.

F. Given the formula of a molecular compound, write its correct name; given the name of a molecular compound, write its formula.

G. Draw the Lewis dot formulas for molecular compounds with multiple bonds.

H. Predict the three-dimensional structure of a molecule and classify it as polar or nonpolar.

I. Use electronegativity to determine the polarity of a bond or a molecule.

On a scale of 1 (low) to 10 (high), how well do you think your performance on this exam demonstrated your understanding of these learning goals?

1 2 3 4 5 6 7 8 9 10

Why did you choose this ranking? What learning objective(s) did you enjoy studying the most from this unit?

A B C D E F G H I

What learning objective(s) did you enjoy studying the least from this unit?

A B C D E F G H I

Did you meet the goal you set for yourself for this unit? If yes, explain what was successful in helping you reach your goal.

If no, describe what you could have done to help you reach your goal.

54

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Unit 3: Ionic and Molecular Compounds Name Block · Unit 3: Ionic and Molecular Compounds Name _____ Block _____ Learning Goals Your Prior Understanding of Learning Goals ... Transitions

Unit 3: Ionic and Molecular Compounds Name Block · Unit 3: Ionic and Molecular Compounds Name _ Block _ Learning Goals Your Prior Understanding of Learning Goals ... Transitions