Predict formulas and names Compounds

Match the following terms to their definitions: Ionic compound, Molecular compound, Cation, Anion, Polyatomic ion.

• A chemical species composed of two or more atoms covalently bonded that has an overall charge.

• A positively charged ion.

• A compound where electrons are transferred between metals and non-metals.

• A negatively charged ion.

• A compound where electrons are shared between non-metals.

Answer explanation

An ionic compound involves electron transfer between metals and non-metals, forming cations (positively charged ions) and anions (negatively charged ions). A molecular compound consists of atoms sharing electrons.

Tags

NGSS.HS-PS1-1

What happens to metals in ionic bonding?

• Gain electrons

• Lose electrons

• Share electrons

• Become negatively charged

Answer explanation

In ionic bonding, metals lose electrons to achieve a stable electron configuration. This loss of electrons results in the formation of positively charged ions, making 'Lose electrons' the correct choice.

In a molecular compound, electrons are:

• Transferred

• Gained

• Lost

• Shared

Answer explanation

In a molecular compound, electrons are shared between atoms to form covalent bonds. This sharing allows each atom to achieve a more stable electron configuration, distinguishing molecular compounds from ionic compounds where electrons are transferred.

Which of the following compounds is molecular?

• CO2

• NaCl

• CuCl2

• Fe(NO3)3

Answer explanation

CO2 is a molecular compound made of covalently bonded carbon and oxygen atoms. In contrast, NaCl, CuCl2, and Fe(NO3)3 are ionic compounds, formed from the electrostatic attraction between ions.

Tags

NGSS.MS-PS1-1

Which of the following compounds has a polyatomic ion?

• NaCl

• MgCO3

• KCl

• Li2O

Answer explanation

MgCO3 contains the polyatomic ion carbonate (CO3^2-), while NaCl, KCl, and Li2O consist of only monatomic ions. Therefore, MgCO3 is the correct choice.

What is the correct name for Ca(ClO)2?

• Calcium hypochlorite

• Calcium chloride

• Calcium perchlorate

• Calcium dichloride

Answer explanation

Ca(ClO)2 is named calcium hypochlorite because it contains calcium (Ca) and hypochlorite ions (ClO). The other options refer to different compounds, making calcium hypochlorite the correct name.

Tags

NGSS.MS-PS1-1

Molecular compounds tend to have lower melting and boiling points compared to ionic compounds.

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OFF

Answer explanation

Molecular compounds have weaker intermolecular forces compared to the strong ionic bonds in ionic compounds. This results in lower melting and boiling points for molecular compounds.

Tags

NGSS.HS-PS1-3

Ionic compounds conduct electricity when dissolved in water.

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OFF

Answer explanation

Ionic compounds dissociate into ions when dissolved in water. These free-moving ions allow the solution to conduct electricity, making the statement true.

Tags

NGSS.HS-PS2-5

Multivalent ions only form one type of ion.

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OFF

Answer explanation

Multivalent ions can form multiple types of ions due to their ability to lose different numbers of electrons. Therefore, the statement is incorrect; multivalent ions do not only form one type of ion.

Polyatomic ions are composed of only one atom.

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OFF

Answer explanation

The statement is false. Polyatomic ions consist of two or more atoms bonded together, unlike monatomic ions, which are made of only one atom.