Polarity and Bonding

Two pure elements react to form a compound. One element is an alkali metal, X, and the other element is a halogen, Z. Which of the following is the most valid scientific claim that can be made about the compound?

• It does not dissolve in water.

• It contains ionic bonds.

• It contains covalent bonds.

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NGSS.HS-PS1-1

NGSS.HS-PS1-3

Of the following compounds, which is the most ionic?

• SCl₄

• BrCl

• PCl₃

• Cl₂O

• CaCl₂

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NGSS.HS-PS1-3

Which of the following compounds contains both ionic and covalent bonds?

• SO₃

• C₂H₅OH

• MgF₂

• H₂S

• NH₄Cl

The elements C and Se have the same electronegativity value, 2.55. Which of the following claims about the compound that forms from C and Se is most likely to be true?

• The carbon-to-selenium bond is unstable.

• The carbon-to-selenium bond is nonpolar covalent.

• The compound has the empirical formula CSe.

• A molecule of the compound will have a partial negative charge on the carbon atom.

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NGSS.HS-PS1-1

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Which of the following scientific claims about the bond in the molecular compound HF is most likely to be true?

• There is a partial negative charge on the H atom.

• Electrons are shared equally between the H and F atoms.

• The bond is extremely weak.

• The bond is highly polar.

Of the following single bonds, which is the LEAST polar?

• N-H

• H-F

• O-F

• I-F

• O-H

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NGSS.HS-PS1-1

On the basis of the information above, which of the following arranges the binary compounds in order of increasing bond polarity?

• CH₄ < SiCl₄ < SF₄

• CH₄ < SF₄ < SiCl₄

• SF₄ < CH₄ < SiCl₄

• SiCl₄ < SF₄ < CH₄

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NGSS.HS-PS1-1

Which of the following graphs correctly shows the relationship between potential energy and internuclear separation for two hydrogen atoms?

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The potential energy of a system of two atoms as a function of their internuclear distance is shown in the diagram above. Which of the following is true regarding the forces between the atoms when their internuclear distance is x?

• The attractive and repulsive forces are balanced, so the atoms will maintain an average internuclear distance x.

• There is a net repulsive force pushing the atoms apart, so the atoms will move further apart.

• There is a net attractive force pulling the atoms together, so the atoms will move closer together.

• It cannot be determined whether the forces between atoms are balanced, attractive, or repulsive, because the diagram shows only the potential energy

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NGSS.HS-PS1-3

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