Question

Determine whether each of the following compounds is ionic or covalent and draw an appropriate Lewis structure: a. \(\mathrm{K}_{2} \mathrm{O}\) b. \(\mathrm{CHClO}\) (carbon is the central atom) c. \(\mathrm{SrS}\) d. \(\mathrm{CH}_{3} \mathrm{Cl}\) (Carbon is the central atom)

Short answer

a. K2O is ionic. b. CHClO is covalent. c. SrS is ionic. d. CH3Cl is covalent. Lewis structures illustrate the K+ and O2- ions for K2O, shared electron pairs for covalent bonds in CHClO and CH3Cl, and Sr2+ and S2- ions for SrS.

Step-by-step solution

Determine the Type of Bonding in K2O

To determine if K2O is ionic or covalent, look at the elements it consists of. Potassium (K) is a metal and oxygen (O) is a nonmetal. Metals and nonmetals typically form ionic bonds. Therefore, K2O is likely ionic.

Draw the Lewis Structure for K2O

For ionic compounds like K2O, Lewis structures are not typically drawn because they do not share electrons but rather transfer them. However, you can show potassium giving its one valence electron to oxygen, creating K+ and O2- ions.

Determine the Type of Bonding in CHClO

CHClO is made up of nonmetallic elements, which typically form covalent bonds by sharing electrons. Since there are no metals present, CHClO is covalent.

Draw the Lewis Structure for CHClO

With carbon as the central atom, it forms double bonds with oxygen, thus satisfying oxygen's octet. Carbon then shares a single electron with each hydrogen and each chlorine atom, each of the other atoms also satisfies their octet or duet (in the case of hydrogen).

Determine the Type of Bonding in SrS

SrS consists of strontium (Sr), a metal, and sulfur (S), a nonmetal. As with K2O, this metal-nonmetal combination typically results in an ionic compound.

Draw the Lewis Structure for SrS

For the ionic compound SrS, representing the transfer of two valence electrons from Sr to S is sufficient, resulting in Sr2+ and S2- ions.

Determine the Type of Bonding in CH3Cl

CH3Cl consists only of nonmetals (carbon, hydrogen, and chlorine), indicating that it is a covalent compound.

Draw the Lewis Structure for CH3Cl

The central carbon atom forms three single covalent bonds with three hydrogen atoms and a single covalent bond with one chlorine atom, completing all atoms' octets or duets (in the case of hydrogen).

Key concepts

Ionic and Covalent Bonds

At the heart of chemistry lies the understanding of how atoms bind together to form compounds. There are two main types of chemical bonds: ionic and covalent.

Ionic bonds form when one atom, typically a metal, donates one or more electrons to another atom, typically a nonmetal, resulting in positive and negative ions that attract each other. This process is aptly named electron transfer. The compounds formed, such as potassium oxide ((K_{2}O)), consist of ions held together by the strong electrostatic forces between oppositely charged particles.

Covalent bonds, on the other hand, occur when two nonmetals share electrons to obtain a stable electron configuration. This electron sharing allows each atom to achieve a complete octet, contributing to the formation of a molecule. Compounds like methane ((CH_{4})) and chloromethane ((CH_{3}Cl)) are examples where atoms are held together by shared electrons.

Bonding in Compounds

Compounds are substances formed from two or more elements that are chemically bonded. The type of bond—ionic or covalent—depends greatly on the nature of the elements involved.

Compounds with ionic bonding, such as strontium sulfide ((SrS)), typically exhibit high melting and boiling points due to the strong attractions between ions. These compounds also tend to be soluble in water and conduct electricity when molten or in solution, as their ions are free to move.

In covalent compounds like chloromethane ((CH_{3}Cl)), atoms are held together in a definite and stable group by shared electrons, creating molecules. Covalent compounds can range from gases, like carbon dioxide, to large, complex biomolecules like DNA, with widely varying properties.

Electron Transfer in Ionic Compounds

Ionic compounds are typically formed through the electron transfer process. This process involves a metal losing one or more electrons to become a positively charged ion, while a nonmetal gains those electrons to become a negatively charged ion. For instance, in potassium oxide ((K_{2}O)), each potassium atom loses one electron to form K+ ions, and the oxygen atom gains two electrons to form an O2- ion.

The transfer process results in a crystal lattice of ions with each positively charged ion surrounded by negatively charged ions and vice versa, stabilizing the structure and creating a solid under normal conditions. This crystalline structure is a result of the ionic bonds formed between the ions with opposite charges.

Electron Sharing in Covalent Compounds

In contrast to ionic bonds, covalent bonds involve the sharing of electrons between atoms. Such sharing allows each atom in the molecule to attain a stable octet or duet configuration. For example, in chloromethane ((CH_{3}Cl)), the central carbon atom fulfills its octet by forming three covalent bonds with hydrogen atoms and one with a chlorine atom.

The shared electrons count toward the octet of both bonded atoms. Covalent bonds can be single, double, or triple, representing the sharing of one, two, or three pairs of electrons, respectively. This type of bonding is characteristic of a wide range of compounds, including organic molecules and polyatomic ions.