Bonding: General Concepts-- Chapter 8

Lone pairs are localized pairs of electrons that do not participate in bonding. These electrons are found in the outermost shell of an atom and are not shared with any other atom. They are often represented as dots in Lewis dot structures. Lone pairs play a crucial role in determining the shape and reactivity of molecules.

Covalent bonding occurs when electrons are shared between atoms. In this type of compound, atoms achieve a stable electron configuration by sharing electrons with each other. This sharing allows both atoms to have a full outer shell, resulting in a strong bond between them. Therefore, the correct answer is "covalent".

Water contains polar bonds because it is a polar molecule. This is due to the unequal sharing of electrons between oxygen and hydrogen atoms in the water molecule. The oxygen atom is more electronegative than the hydrogen atoms, causing it to pull the shared electrons closer to itself, creating a partial negative charge. The hydrogen atoms, on the other hand, have a partial positive charge. This polarity allows water molecules to form hydrogen bonds with each other and other polar molecules, giving water its unique properties such as high surface tension and ability to dissolve many substances.

Ions with the same amount of electrons are called isoelectronic. This term refers to ions that have the same electronic configuration, meaning they have the same number of electrons and therefore similar chemical properties. Isoelectronic ions can be formed by gaining or losing electrons to achieve a stable electron configuration, resulting in a net positive or negative charge.

Resonance is the special phenomenon in which more than one Lewis structure can be written for a molecule or ion. This occurs when there are multiple ways to arrange the electrons in the molecule or ion while keeping the same overall connectivity of atoms. Resonance structures are represented by using double-headed arrows between them, indicating that the actual structure is an average of the resonance forms. This phenomenon is important in understanding the stability and reactivity of molecules and ions.

A methane atom takes a tetrahedral shape. In a methane molecule, there are four hydrogen atoms bonded to a central carbon atom. The carbon atom has four electron groups around it, which repel each other and arrange themselves as far apart as possible. This results in a tetrahedral shape, where the hydrogen atoms are positioned at the corners of a tetrahedron around the carbon atom. Therefore, the correct answer is tetrahedral.

Polar covalent bonding is the term used to describe unequal sharing of electrons. In this type of bonding, the electrons are not shared equally between the atoms involved. One atom has a higher electronegativity and attracts the electrons more strongly, resulting in a partial positive charge on one atom and a partial negative charge on the other. This unequal distribution of charge creates a polar molecule. Ionic bonding involves a complete transfer of electrons, nonpolar covalent bonding involves equal sharing of electrons, and electronegativity is a measure of an atom's ability to attract electrons in a chemical bond.

Carbon tetrachloride is a non-polar molecule because it consists of four chlorine atoms bonded symmetrically to a carbon atom, resulting in a tetrahedral shape. In this molecule, the chlorine atoms exert equal pull on the shared electrons, causing the molecule to have a symmetrical distribution of charge. As a result, there are no partial positive or negative charges, making carbon tetrachloride non-polar.

Carbon tetrafluoride (CF4) consists of one carbon atom bonded to four fluorine atoms. Carbon is in group 14 of the periodic table, which means it has four valence electrons. Fluorine is in group 17, which means it has seven valence electrons. Therefore, to draw the structure of CF4, we need to consider the total number of valence electrons, which is 4 (from carbon) + 4x7 (from four fluorine atoms) = 32.

Linear molecules with two identical bonds are not polar because the bond dipoles cancel each other out. In a linear molecule, the two identical bonds are oriented in opposite directions, resulting in equal and opposite bond dipoles. As a result, the molecule as a whole has a symmetrical distribution of charge and is nonpolar.

Sulfur is allowed to sometimes break the octet rule because it can expand its valence shell beyond eight electrons. This is possible due to the presence of empty d orbitals in the sulfur atom, which can accommodate additional electrons. As a result, sulfur can form compounds where it has more than eight electrons in its valence shell, allowing it to exceed the typical octet configuration.

In double covalent bonds, two pairs of electrons are shared between two atoms, while in triple covalent bonds, three pairs of electrons are shared. This allows for a stronger bond between the atoms, as more electrons are being shared. In ionic bonds, electrons are transferred from one atom to another, rather than being shared. Single covalent bonds involve the sharing of only one pair of electrons. Therefore, the correct answers are double covalent bonds and triple covalent bonds.

Carbon tetrachloride (CCl4) contains at least one polar bond because it is a tetrahedral molecule with four identical chlorine atoms bonded to a central carbon atom. The chlorine atoms are more electronegative than carbon, causing the electron density to be pulled towards the chlorine atoms, creating partial negative charges on the chlorine atoms and a partial positive charge on the carbon atom. This unequal distribution of charge results in a polar bond between carbon and chlorine, making the statement true.

In water, each hydrogen atom has a formal charge of 0. This is because hydrogen is less electronegative than oxygen, so the electrons in the covalent bond are more attracted to the oxygen atom. As a result, the hydrogen atom does not gain or lose any electrons and the formal charge is 0.

The given answer is correct because K (+1), Cl (-1), and Ar all have the same number of electrons. K (+1) has lost one electron, Cl (-1) has gained one electron, and Ar has a full valence shell with no net charge. Therefore, they all have the same electron configuration and are considered to be isoelectronic.