Chem 101 Written Exam

Cesium will typically form a _____ cation.

1+ Cesium has one lone valence electron, so it will typically lose that electron to become a 1+ cation and gain xenon electron configuration.

The Lewis symbol for sodium will have how many dots?

1 As sodium has one valence electron, its Lewis symbol will have one dot.

The octet rule predicts that fluorine will tend to make ____ bond(s).

1 With three lone pairs and one unpaired electron, fluorine will gain an octet by making one covalent bond.

The symbol used for partial charges is a lowercase:

A lowercase delta (δ) is the symbol we use for partial charges.

What is the electron configuration of Br−?

Ar]4s23d104p6 The electron configuration of Br− would be 1 more electron than the original configuration of Br giving us [Ar]4s23d104p6.

C12H22O11 is an example of a(n):

C12H22O11 is an example of a molecular compound because it consists of two or more elements that are nonmetals, and are covalently bonded.

Carbon tetrabromide has the formula __________.

CBr4

Which element does NOT have multiple stable cations? Fe Ni Ti Ga

Ga Gallium is not a transition metal but rather a p block element, so it will tend to lose its p electron and both of its s electrons to form the 3+ ion. While transition metals commonly form multiple stable cations.

An example of a polar covalent bond is: Select the correct answer below: H-H H-Cl Cl-Cl none of the above

H-Cl The chlorine attracts electrons more strongly than the hydrogen, so this will be a polar covalent bond.

Which of the following is a molecular compound? Li2CO3 KI H2O2 CaF2

H2O2, or hydrogen peroxide, consists of covalently bonded nonmetals, and is therefore molecular.

Which molecule has the most lone pairs? Select the correct answer below: CH4 NH3 H2O HF

HF The hydrogen fluoride atom will have three lone pairs, whereas water has two, ammonia has one, and methane has none.

Which of the following is a molecular compound? HF NaF CaCl2 MgO

HF is a compound consisting of two nonmetals, which will form a covalent bond. Molecular compounds are composed of covalently bonded nonmetals.

Which of the following elements will form a molecular compound with one another? F and Na F and Ca F and Mg F and O

F and O Oxygen is the only other nonmetal listed, so it is the only combination that could yield a molecular compound.

Which of the following has a polar covalent bond? Select the correct answer below: H2 Cl2 HI O2

HI has a polar covalent bond. All of the other molecules listed are diatomic molecules of a single element, so the bonds in each of these are pure covalent.

Potassium selenide is formed from the K+ cation and the Se2− anion. What is the correct formula for this compound?

K2Se An ionic compound must be electrically neutral, so it must have the same number of positive and negative charges. Two potassium ions, each with a charge of 1+, would give us two positive charges, while one selenide ion, with a charge of 2−, would give us two negative charges. Therefore, the formula is two potassium ions to one selenide ion: K2Se.

Lithium arsenide is formed from the Li+ cation and the As3− anion. What is the correct formula for this compound?

Li3As An ionic compound must be electrically neutral, so it must have the same number of positive and negative charges. Three lithium ions, each with a charge of 1+, would give us three positive charges, while one arsenide ion, with a charge of 3−, would give us three negative charges. Therefore, the formula is three lithium ions to one arsenide ion: Li3As.

Which of the following is a molecular compound? TiBr3 Cu3P N2O4 NH4Cl

N2O4 is a molecular compound. The other choices are ionic compounds.

Identify the compound with the pure covalent bond. Not quite - review the answer explanation to help get the next one. O2 HCl SO2 all of the above

O2 O2 has a pure covalent bond because the atoms it contains are identical and thus the electrons in this bond are shared equally.

All of the following are ionic compounds except: Select the correct answer below: SO2 NaOH FeBr3 SrI2

SO2 is a covalent compound.

Which element will NOT commonly form a 3− anion? Select the correct answer below: Sc As Sb P

Sc Scandium will tend to form the 3+ cation, but not the 3− anion because it is a metal and metals form cations not anions.

Which of the following anions is most likely to form? Select the correct answer below: Br2− S− Se3− Te2−

Te2− Tellurium will tend to gain two electrons to fill its valence shell. Sulfur and selenium also should become 2−, while bromine should become 1−.

Titanium (IV) oxide is formed from the Ti4+ cation and the O2− anion. What is the correct formula for this compound?

TiO2 An ionic compound must be electrically neutral, so it must have the same number of positive and negative charges. One titanium ion, with a charge of 4+, would give us four positive charges, while two oxide ions, each with a charge of 2−, would give us four negative charges. Therefore, the formula is one titanium ion to two oxide ions: TiO2.

An ion will form when a neutral atom gains or loses __________.

electrons

Different ions of a given element will have differing numbers of __________.

electrons

In a pure covalent bond:

electrons are shared evenly

In general, covalent bonding can occur between which of the following?

Two neutral atoms

A single shared pair of electrons forms:

a single bond

Which of the following does not correctly match the ion name with its ion symbol? Select the correct answer below: magnesium cation, Mg2+ barium cation, Ba2+ aluminum cation, Al3− iodide, I−

aluminum cation, Al3− All of the answer choices are correctly paired except for the aluminum cation, whose symbol should be Al3+.

What is a cation?

an atom that has lost electrons

Neutral nonmetal atoms typically gain electrons, thus becoming __________.

anions

Ca(OH)2 is called __________.

calcium hydroxide

All positively charged ions are called __________.

cations

Metals usually form positively charged ions, which are also called __________.

cations

CuOH is called:

copper(I) hydroxide As the hydroxide has a charge of 1−, the copper atom must have a charge of 1+, thus we use the roman numeral I.

What type of bond is characteristic of a molecular compound?

covalent bonds

In general, electronegativity

increases from left to right across a period in the periodic table and decreases down a group.

Electrons in a pure covalent bond:

have an equal probability of being near either nucleus

Ionic compounds tend to have:

high melting points, high boiling points, and high water solubility

Which of the following is correct nomenclature for a binary acid?

hydrofluoric acid

Hydrogen iodide, when placed in water, will be called:

hydroiodic acid Following the rules of nomenclature will give us hydroiodic acid. The word "hydrogen" is changed to the prefix hydro- The other nonmetallic element name is modified by adding the suffix -ic The word "acid" is added as a second word

Ions comprised of a single atom are known as __________.

monatomic ions

Electrons in a polar covalent bond are shifted toward the:

more electronegative atom

If an atom has a full octet, it will have:

noble gas electron configuration

The _______ is the tendency of main group elements to form enough bonds to obtain eight valence electrons.

octet rule

A polar covalent bond is characterized by a __________ charge on one atom, and a ___________ charge on the other.

partial positive; partial negative

In a polar covalent bond, the atom that has electron excess will be:

partially negative

In a polar covalent bond, the atom that is electron deficient will be:

partially positive

What is the name of oxyacid: H3PO4?

phosphoric acid

What is the name for the binary compound: PCl3?

phosphorus trichloride

Bonds that are composed of electrons shared unequally between two atoms are called __________.

polar covalent bonds

Once all of the valence electrons have been placed on a Lewis structure:

rearrange electrons to satisfy the octet rule If there are atoms without a full octet, we can move lone pairs and covalent bonds around in an effort to fill those octets.

s block elements lose their _____ electrons first.

s

Ionic compounds are also known as:

salts

The electrons in pure covalent bonds are:

shared equally

H2SO3 is called:

sulfurous acid

In a molecule of HCl:

the chlorine atom is partially negative

In a polar covalent bond, the atom that attracts the electrons more strongly has:

the partial negative charge

When an element loses its valence electrons to form a cation, it assumes the electronic structure of:

the preceding noble gas

What is the name of SnO2?

tin (IV) oxide SnO2 is an ionic compound with a tin cation and the oxide anion. Tin can have multiple charges, so the name must indicate the charge with a roman numeral. To find the charge on the tin cation, use the fact that oxide has a charge of −2. There are two oxide anions, so the charge on the tin cation must be +4 in order to give a neutral charge overall. 1(+4)+2(−2)=0.

Elements in the same group have the same number of __________.

valence electrons

How many bonds would nitrogen need to form to obtain an octet?

3 Nitrogen would need 3 bonds to form an octet because it already has 5 electrons.

A double bond contains how many electrons?

4 Each covalent bond contains two electrons, so a double bond contains four electrons.

Which is NOT a typical cation of chromium? 2+ 3+ 5+ 6+

5+ Most transition metals will readily form 2+ and 3+ ions. The electron configuration for neutral chromium is 1s22s22p63s23p64s13d5. Chromium is a d-block transition metal, and so the valence electrons are removed from the ssubshell before they are removed from the d subshell. Therefore, Chromium would lose its one s electron first and a delectron to form Cr2+, which is only stable in the absence of air. Chromium can lose two more d electrons to become Cr3+, which is the most stable oxidation state for chromium. Chromium can also lose all the remaining valence electrons to become Cr6+. Chromium is seen in this oxidation state in chromium(VI) sulfide Cr2S3.

The Lewis symbol for chlorine will have how many dots?

7 Chlorine has seven valence electrons, so its Lewis symbol will have seven dots.

Which of the following is a characteristic of ionic solids? Select the correct answer below: Their ionic bonds are very strong Ionic solids are poor conductors of electricity Ionic solids dissolve easily in water All of the above

All of the above The properties of ionic compounds shed some light on the nature of ionic bonds. Ionic solids exhibit a crystalline structure and tend to be rigid and brittle; they also tend to have high melting and boiling points, which suggests that ionic bonds are very strong. Ionic solids are also poor conductors of electricity for the same reason. Most ionic solids, however, dissolve readily in water.

Ions may consist of __________.

Ions can be either monoatomic, consisting of one atom, or polyatomic, consisting of multiple atoms. There is no specific limit to the number of atoms in an ion.

Mg3N2 consists of __________.

Mg2+ and N3− ions From the periodic table, we know that magnesium will form 2+ ions, and nitrogen will form 3− ions. The two will, therefore, come together in a 3:2 ratio to form a neutral compound.

Magnesium fluoride is formed from the Mg2+ cation and the F− anion. What is the correct formula for this compound?

MgF2 An ionic compound must be electrically neutral, so it must have the same number of positive and negative charges. One magnesium ion, with a charge of 2+, would give us two positive charges, while two fluoride ions, each with a charge of 1−, would give us two negative charges. Therefore, the formula is one magnesium ion to two fluoride ions: MgF2.

Manganese oxide is formed from Mn5+ cations and O2− anions. What will be its chemical formula?

Mn2O5 An ionic compound must be electrically neutral, so it must have the same number of positive and negative charges. Two manganese cations, each with a charge of 5+, would give us ten positive charges, while five oxygen anions, each with a charge of 2−, would give us ten negative charges. Therefore, the formula would be Mn2O5.

What is the formula of the ionic compound sodium chromate?

Na2CrO4 Step 1: Identify the symbol of the cation.Result of this step = Na+. Step 2: Identify the formula of the anion.Result of this step = CrO2−4. Step 3: Use the minimum number of cations and anions needed to make the sum of all charges in the formula equal to zero.Result of this step = Na+ has a 1+ charge and CrO2−4 has a 2− charge, which do NOT equate to zero. In order to balance the charges, you need 2 Na+ for every one CrO2−4. The resulting formula of this compound is Na2CrO4.

Which of the following is NOT a covalent compound? CO2 Na2O H2O NH3

Na2O Sodium is a metal and oxygen is a nonmetal, so this will be an ionic compound.

Neutral atoms that gain electrons become __________.

Neutral atoms that gain electrons become anions (negatively charged ions).

Which describes an ionic compound?

They are generally solids.

What is the abbreviated electron configuration of Mn2+?

[Ar]3d5 The abbreviated electron configuration of Mn is [Ar]4s23d5. Because Mn is a d-block transition metal, the electrons of the s subshell are removed before the (n−1)d electrons. Thus the abbreviated electron configuration for Mn2+ is [Ar]3d5.

What is the electron configuration of As3−?

[Ar]4s23d104p6 The electron configuration of As3− would be 3 more electrons than the original configuration of As. Therefore, the electron configuration of As3− is 1s22s22p63s23p64s23d104p6. Alternatively, this can be written as [Ar]4s23d104p6 or [Kr].