Answers PBCSD_Grade_Forgiveness_2003310_Physical Science_S1_2022Covalent Bonds

Covalent Bonds — Unit test Answers

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Sal drew the electron dot diagram of an aluminum atom as shown.

He should add five more dots so that the atom obeys the octet rule.

He should add ten more dots so that all thirteen electrons are shown.

He should add a single dot below the symbol.

He should add one dot below and one dot to the left of the symbol.

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Which refers to the type of chemical bond that involves the transfer of electrons between atoms?

metallic

polar covalent

ionic

covalent

The table describes the properties of four compounds.Which compounds are most likely ionic?

compounds A and B

compounds B and C

compounds C and D

compounds D and A

Which is a characteristic of all ions?

They are metals.

They have a charge.

They are made of two or more types of atoms.

They form chemical bonds through electron sharing.

What best explains whether bromine (Br) or neon (Ne) is more likely to form a covalent bond?

Bromine forms covalent bonds because it has seven valence electrons, but neon has eight valence electrons and already fulfills the octet rule.

Bromine forms covalent bonds because it has many electron shells, but neon has only two electron shells and is tightly bound to its electrons.

Neon forms covalent bonds because it can share its valence electrons, but bromine has seven valence electrons and can gain only one more electron.

Neon forms covalent bonds because it has only two electron shells, but bromine has many electron shells and will lose electrons in order to fulfill the octet rule.

Which is most likely a covalent compound?

LiF

MgS

NH3

CaCl2

What does the octet rule state that explains why atoms bond?

An atom bonds to have eight valence electrons to become stable.

An atom bonds to lose eight valence electrons to become stable.

An atom bonds to have eight valence electrons to become unstable.

An atom bonds to lose eight valence electrons to become unstable.

An atom of lithium (Li) forms an ionic bond with an atom of chlorine (Cl) to form lithium chloride. How are the valence electrons of these atoms rearranged to form this bond?

A few valence electrons are shared between the atoms.

Many valence electrons are shared between the atoms.

Electrons are transferred from the chlorine atom to the lithium atom.

Electrons are transferred from the lithium atom to the chlorine atom.

Which ionic compound is used as a building material?

salt

limestone

magnesium oxide

iron oxide

Shameeka is studying for an exam. She took the notes below about calcium and chlorine, which are known to form ionic bonds.Calcium, which is a metal, donates 2 electrons to chlorine.The individual calcium atoms become ions with a negative 2 charge. The bond between calcium and chlorine makes the atoms stable. Calcium and chlorine attract each other. Which best describes Shameeka’s error?

Calcium is a metal, so it donates protons, not electrons.

The individual calcium atom has a positive, not negative, 2 charge.

The bond formed makes the atoms unstable, not stable.

Calcium and chlorine repel, not attract, each other.

To what extent do covalent compounds conduct electricity?

always

usually

rarely

never

Which describes the substances that form covalent bonds?

a metal and a metalloid

a metal and a nonmetal

two nonmetals

two metals

The compound ethylene (C2H4) is represented by this diagram.

Each carbon atom shares two electrons with one hydrogen atom and also shares two electrons with the other carbon atom.

Each carbon atom shares four electrons with one hydrogen atom and also shares four electrons with the other carbon atom.

One electron is shared between each hydrogen atom and the carbon atom bonded to it, and two electrons are shared between the carbon atoms.

Two electrons are shared between each hydrogen atom and the carbon atom bonded to it, and four electrons are shared between the carbon atoms.

Which best describes most covalent compounds?

resilient

brittle

cold

warm

In carbon dioxide (CO2), there are two oxygen atoms for each carbon atom. Each oxygen atom forms a double bond with carbon, so the molecule contains two sets of double bonds.Two sets of double bonds means that the total number of electrons being shared in the molecule is

two.

four.

six.

eight.

Iodine and potassium form an ionic bond. Iodine has seven electrons in its outer shell, and potassium has one electron in its outer shell. Which conclusion is best supported by this information?

Iodine is a noble gas.

Potassium is a nonmetal.

Iodine becomes an ion with a negative 1 charge.

Potassium becomes an ion with a positive 7 charge.

Fluorine (F) and bromine (Br) are in the same group on the periodic table. How do atoms of these elements compare when they form bonds?

Both a fluorine atom and a bromine atom lose one electron, and both atoms become stable.

A fluorine atom becomes stable by losing one electron, but a bromine atom cannot become stable by losing only one electron.

Both a fluorine atom and a bromine atom gain one electron, and both atoms become stable.

A fluorine atom becomes stable by gaining one electron, but a bromine atom cannot become stable by gaining only one electron.

Which product relies on the ability of ionic compounds to conduct electricity?

paper

batteries

soap

glazed pottery

Which two elements will most likely form an ionic bond? (Click on the periodic table icon to view these elements)

krypton and lithium

magnesium and bromine

calcium and potassium

iodine and chlorine

Which atom is most likely to form a metallic bond?

aluminum (Al)

helium (He)

phosphorus (P)

carbon (C)

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Covalent Bonds — Unit test Answers

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