1. Which of the following would be considered an ionic compound?
a. CH4
b. SO
c. LiCl
d. N2O4
An ionic compound is formed between cations and anions.
... [Show More] Typically, the cation is a metal
and the anion is a nonmetal. In this case LiCl is the ionic compound.
2. In general an ionic bond forms between atoms classified as:
a. metals and nonmetals
b. more than one metal
c. transition metals
d. more than one nonmetal
Metals and nonmetals interact to form ionic compounds.
3. In an ionic bond electrons are:
a. created
b. destroyed
c. shared
d. Transferred
In an ionic compound, electrons are transferred, forming a cation and an anion. The cation
and anion are then held together by electrostatic forces (think opposites attract).
4. Which of the following would you classify as a polyatomic cation?
a. NH4+
b. F-
c. O2-
d. OHPolyatomic ions are molecular compounds that have an overall, or net, charge. Cations are
positively charged ions. NH4+ is a polyatomic cation.
As we see in the examples of ionic bonds here, metals lose electrons, forming cations, while nonmetals will gain electrons, forming anions. The resulting charge differences hold the ionic
compound together.
Molecule Cation Anion
Element that
lost one or more
valence
electrons
Element that
gained one or
more valence
electron
KF K
+ F
- K F
MgCl2 Mg2+ Cl- Mg Cl
Li2O Li+ O
2- Li O
Al2S3 Al3+ S
2- Al S
FeCl3 Fe3+ Cl- Fe Cl
As we see in the examples the charges of these molecules cancel out.
Molecule Number of
cations
Charge of each
cation
Number of
anions
Charge of each
anion
Na2S 2 +1 1 -2
Mg3N2 3 +2 2 -3
AlBr3 1 +3 3 -1
You may recognize some of these simple ionic compounds on the back of food labels. The
correct answers are Calcium oxide, Magnesium phosphide, Sodium iodide, Sodium
phosphide, and Lithium sulfide.
The crossover method is useful for determining the structure of ionic compounds. The
correct answers are Mg3P2, Al2S3, Ca3P2
Aluminum Nitrite= Al(NO2)3
Ammonium Sulfate= (NH4)2SO4
Calcium Phosphate= Ca3(PO4)2
Ammonium Nitrate= NH4NO3
Sodium Phosphate= Na3PO4, Contact solution
Sodium Chloride= NaCl, Skincare products
Sodium Bicarbonate= NaHCO3, Deodorant
5. Which of the following would be considered an ionic compound? Select all that apply.
a. CaSO4
b. CaO
c. N3O6
d. Mg3P2
e. CF4
A good indication that you have an ionic compound is that you have the interaction
between atoms classified as metals forming cations with those classified as nonmetals
forming anions. Polyatomic ions can also act as cations or anions in ionic compounds.
Mg3P2, CaO, and CaSO4 are all ionic compounds. The other options do not contain either
a metal or a polyatomic ion.
6. What would be the name of the compound with the name Na2O?
a. Sodium oxygen
b. Sodium oxide
c. Sodium Hydroxide
d. Sodium dioxide
For naming simple ionic compounds, we give the first atom the elemental name and the
second atom uses the element name using the ~ide suffix. Na2O is sodium oxide.
7. Na3PO4 would be named as
a. Trisodium phosphide
b. Trisodium phosphate
c. Sodium phosphide
d. Sodium phosphate
When naming an ionic compound containing a polyatomic ion, the polyatomic ion keeps
the original name. We also do not use any prefixes in ionic compounds. Na3PO4 is sodium
phosphate.
8. I would expect the compound NaBr to: (select all that apply)
a. conduct electricity if dissolved in water
b. dissolve in oil
c. dissolve in water
d. have a crystalline structure
Be sure to review the properties of ionic compounds as they are different from the
properties of other molecules you will be studying and we want to be able to contrast these
properties. Ionic compounds dissolve in water, have crystalline structure, are hard/brittle,
and conduct electricity in water.
When naming an ionic compound containing a polyatomic ion, the polyatomic ion keeps
the original name. If the nonmetal anion is an element, we instead use the ~ide suffix.
Na3N is sodium nitride, NaNO3 is sodium nitrate, NaNO2 is sodium nitrite, NaBr is
sodium bromide, and Na2CO3 is sodium carbonate.
9. What would be the chemical formula for Calcium Phosphate?
a. CaPO4
b. CaPO42
c. Ca3P2
d. Ca3(PO4)2
When working with polyatomic ions, we want to be sure to use parenthesis to clearly show
how many of that polyatomic ion we have in the chemical formula. Calcium phosphate is
Ca3(PO4)2.
10. In the bond(s) within ionic compounds, what is holding the atoms together?
a. Sharing of electrons
b. Electrostatic attraction
c. Hydrogen bonding
d. Attraction between multiple metals
When an ionic bond is formed, electrons are transferred from the species forming the
cation (usually a metal) to the species forming the anion (usually a nonmetal). Once the
electrons are exchanged, the ions are held together through electrostatic interaction.
11. In a reaction forming an ionic bond, which of the following would NOT be expected to
occur?
a. The transfer of two valance electrons from a metal to a nonmetal
b. The sharing of two valance electrons between two nonmetals
c. The transfer of a valance electron from a metal to a nonmetal
d. The transfer of a valance electron from a metal to a polyatomic ion
In the formation of an ionic bond, one or more electrons are transferred. Typically, this
transfer happens from a metal to a nonmetal. The sharing of two valance electrons between
two nonmetals is not expected to occur.
12. If an ionic bond forms between an atom of Al and an atom of N, how many valance
electrons are transferred?
a. 1
b. 4
c. 2
d. 3
Al has 3 valance electrons and N has 5 valance electrons. When 3 electrons are transferred
to the N from the Al, both will have a full valance shell.
13. In an ionic compound, the total charge of the compound must balance out to:
a. 0
b. +1
c. -1
d. -2
The overall charge on an ionic compound must equal zero for a stable compound to form.
14. The compound nitrogen trifluoride would have what chemical formula?
a. NF3
b. (NF)3
c. NF
d. N3F
When naming molecular compounds (compounds containing only covalent bonds), we use
prefixes such as mono, di, and tri to show how many of each atom a molecule contains.
Nitrogen trifluoride is NF3
15. Which of the pairs of atoms below would be expected to make covalent bonds? Select
all that apply:
a. Sodium and bromine
b. Carbon and chlorine
c. Hydrogen and oxygen
d. Calcium and nitrogen
Covalent forms tend to form between two atoms classified as non-metals. Sodium and
calcium are both metals and so those choices are not correct.
In a covalent bond, electrons are:
a. transferred
b. destroyed
c. shared
d. taken
In covalent bonds, electrons are shared between the atoms within the bond.
Covalent bonds form from atoms classified as non-metals. These atoms could be different,
such as in N2O3, or the same, as is the case with S8. H2O and S2F10 also form covalent
bonds. If a molecule contains a metal, we would expect an ionic bond instead of a covalent
bond to form.
16. What is the chemical name of water, H2O?
a. Trihydrogen monoxide
b. Dihydrogen oxide
c. Hydrogen oxide
d. Dihydrogen monoxide
Since there are two hydrogens and one oxygen, this would be dihydrogen monoxide.
Covalent bonds involve the sharing of electrons and is between nonmetals. There are only
two electrons in each single covalent bond and the driving force for this bonding
interactions is having a valance shell that needs additional electrons to fill. The correct
answers are the I I sharing and the I F sharing.
Two atoms of Phosphorous= Triple bond. Lithium and Bromine= Ionic bond (metal and
nonmetal). Hydrogen and Chlorine= Single bond. Sulfur and Oxygen= Double bond.
17. Select all compounds that you would expect to contain covalent bonds.
a. MgCl2
b. O3
c. Na3N
d. C2H6
e. N4O6
Bonds between nonmetals tend to be covalent in nature as they share electrons. C2H6,
N4O6, and O3 all contain covalent bonds. MgCl2 and Na3N both contain metals and so the
bonds would not be covalent.
18. What type of bond would you expect to form between two oxygen atoms?
a. Ionic bond
b. Single covalent bond
c. Double covalent bond
d. Triple covalent bond
As both oxygen atoms have two unpaired electrons, we would expect a double bond to
form.
19. What is the name of the compound P2O5?
a. Phosphorus oxide
b. Phosphorus tetroxide
c. Phosphorus oxygen
d. Diphosphorus pentoxide
The prefixes help us to determine chemical formula. P2O5 is diphosphorus pentoxide.
20. What is the chemical formula for nitrogen trifluoride?
a. N2F2
b. NF
c. NF3
d. N4F
The prefixes help us to describe how many of each atom are in a molecular compound.
Nitrogen trifluoride is NF3
21. Select the pairs of atoms you would expect to form single covalent bonds. Select all that
apply.
a. Two atoms of O
b. O and S
c. an atom of F and an atom of H
d. H and Cl
e. Two atoms of Cl
Nonmetals with one unpaired electron tend to form covalent bonds. In this case you would
expect H and Cl, Cl and Cl, and F and H to form single covalent bonds.
22. What shape would you expect the compound Hydrogen Fluoride to have?
a. Pyramidal
b. Tetrahedral
c. Bent
d. Linear
Since there are only two atoms, and you can make a line between any two points, the shape
of this molecule would be linear.
23. Which of the following substances would you not expect to dissolve in water?
a. Salt
b. Alcohol
c. Sugar
d. Oil
You have likely noticed in the kitchen that oil and water to do not mix together. This has to
do with hydrogen bonding.
There are two electrons in each covalent bond. Nonmetals can also make double or triple
bonds to one another, by making two or three covalent bonds between two atoms
respectively. The correct one is:
Hydrogen atoms each have 1 unpaired valence electron while an oxygen atom has 2
unpaired valence electrons.
24. Between an atom of hydrogen and an atom of oxygen, which do you think could make
more covalent bonds?
a. oxygen
b. hydrogen
Hydrogen only has one unpaired valance electron, each hydrogen atom can only make one
covalent bond. As an oxygen atom has two unpaired valance electrons, each oxygen can
make two single covalent bonds or one double covalent bond.
Use the flow chart and Lewis Dot Structure to determine the shapes. CO2= Linear. NH3=
Trigonal pyramidal. H2S= Bent. CCl4= Tetrahedral. PF3= Trigonal pyramidal.
HCl= Cl. OP= O. NO= O. SeCl= Cl. FO= F. SCl= Cl.
25. Select all molecules that you would expect to contain one or more polar covalent bonds.
Select all that apply.
a. CF4
b. P2Br6
c. O3
d. CH4
e. NaF
Polar covalent compounds have at least two different nonmetal elements, giving an
electronegativity difference. Key to note here is that NaF is not considered polar because
Na is a metal and covalent bonds are between non-metals. Also, CH4 is not considered
polar as C and H have very similar electronegativity values. CF4 & P2Br6 are polar
covalent compounds.
The key to Lewis Dot Structure is to put the atom that can make the most covalent bonds,
as determined by number of unpaired electrons, in the middle and then put all the other
atoms around the center atom and match unpaired electrons until all have eight valance
electrons (except for H which should have 2). S has two spots to fill and Br has one spot to
fill each. This is the correct choice:
26. Which of the molecules below would you expect to participate in hydrogen bonding?
Select all that apply.
a. H2S
b. NH3
c. CH4
d. HCl
Hydrogen bonding occurs when polar molecules containing hydrogen interact with another
molecule with a negative or partial negative charge to form an intermolecular interaction.
H2S, NH3, and HCl have hydrogen bonds.
Electron areas such as bonds and unpaired electrons will repel one another, resulting in the
shapes.
CF4= Tetrahedral
PCl3= Trigonal pyramidal
CH2S= Trigonal planar
CO2= Linear
SeF2= Bent
27. Select all molecules that you would expect to contain one or more polar covalent bonds.
a. BrF
b. N2O4
c. CaCl2
d. S8
e. CF4
Polar covalent bonding involves unequal sharing of electrons. Be sure to review
electronegativity trends to help determine when there is unequal sharing of electrons,
indicating a polar covalent compound. Also, be sure to note that ionic compounds are not
classified as as polar compounds. BrF, N2O4, and CF4 have polar covalent bonds.
28. In which of the following molecules would you expect to contain nonpolar bonds. Select
all that apply
a. S8
b. HF
c. H2S
d. N2
Nonpolar covalent compounds involve near equal sharing of electrons. Be sure to review
how lack of significant electronegativity differences results in the near equal sharing of
electrons. N2 and S8 contain nonpolar bonds.
29. The double helix structure of or DNA is held together by
a. Covalent bonds
b. Ionic bonds
c. Metal to metal bonds
d. Hydrogen bonds
Hydrogen bonds are an important intermolecular force that explains the boiling point and
viscosity of water and is also involved in many important biological processes including
holding bases in DNA together and protein folding. [Show Less]