Unit 5 Review

The attractive force that binds atoms in a molecule is known as a:

• Chemical bond

• Ionic force

• Magnetic bond

• Electromagnetic interaction

Answer explanation

The attractive force that binds atoms in a molecule is called a chemical bond. This term encompasses various types of bonds, including ionic and covalent bonds, which are essential for forming molecules.

Which of the following elements is least likely to form a covalent bond?

• H

• N

• Mg

• Cl

Answer explanation

Mg (magnesium) is a metal and typically forms ionic bonds by losing electrons, rather than covalent bonds where atoms share electrons. In contrast, H, N, and Cl are nonmetals that readily form covalent bonds.

Tags

NGSS.HS-PS1-1

A polar molecule is characterized by:

• Symmetrical charge distribution

• An uneven charge distribution

• No charge distribution

• A balanced ionic state

Answer explanation

A polar molecule has an uneven charge distribution due to differences in electronegativity between atoms, leading to partial positive and negative charges. This distinguishes it from nonpolar molecules, which have symmetrical charge distribution.

The correct Lewis dot structure for ammonia (NH3) illustrates that:

• Nitrogen has three bonded pairs and one lone pair

• Each hydrogen atom has a full octet.

• Ammonia has only ionic bonds.

• Nitrogen has no lone pairs.

Answer explanation

The correct Lewis dot structure for ammonia (NH3) shows nitrogen with three bonded pairs (to hydrogen atoms) and one lone pair. Each hydrogen has only two electrons, not a full octet, and ammonia has covalent, not ionic, bonds.

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NGSS.HS-PS1-2

The attraction of free-floating valence electrons for positively charged metal ions is called a metallic bond.

• True

• False

Answer explanation

True. Metallic bonds are formed due to the attraction between free-floating valence electrons and positively charged metal ions, allowing metals to conduct electricity and heat.

The electrostatic attraction that binds oppositely charged ions together by transferring electrons is called an ionic bond.

• True

• False

Answer explanation

True. An ionic bond is formed through the electrostatic attraction between oppositely charged ions, which occurs when electrons are transferred from one atom to another.

Tags

NGSS.HS-PS1-3

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Atoms tend to react so as to acquire the stable electron configuration of a noble gas.

• True

• False

Answer explanation

True. Atoms seek to achieve a stable electron configuration similar to that of noble gases, which have full outer electron shells, making them less reactive.

Tags

NGSS.HS-PS1-1

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According to the VSEPR model, what is the molecular geometry of ammonia (NH3)?

• Bent

• Linear

• Trigonal planar

• Pyramidal

Answer explanation

According to the VSEPR model, ammonia (NH3) has a central nitrogen atom bonded to three hydrogen atoms and one lone pair of electrons. This arrangement results in a pyramidal molecular geometry.

Identify the type of bond described as surrounded by a "sea" of free-flowing electrons, which is malleable and ductile:

• Ionic bond

• Covalent bond

• Metallic bond

• Molecular bond

Answer explanation

The metallic bond is characterized by a 'sea' of free-flowing electrons, allowing metals to be malleable and ductile. This distinguishes it from ionic and covalent bonds, which do not exhibit these properties.

Which of the following compounds is not covalent?

• SCl2

• KCl

• HCl

• PF3

Answer explanation

KCl is an ionic compound, formed by the transfer of electrons between potassium and chlorine. In contrast, SCl2, HCl, and PF3 are covalent compounds, where atoms share electrons.

Tags

NGSS.HS-PS1-1