Question

Predict whether each of the following is held together by ionic or covalent bonds: (a) zinc bromide, \(\mathrm{ZnBr}_{2}\) (b) carbon dioxide, \(\mathrm{CO}_{2}\) (c) iodine heptafluoride, \(\mathrm{IF}_{7}\) (d) lead(II) sulfate, \(\mathrm{PbSO}_{4}\)

Short answer

(a) Ionic, (b) Covalent, (c) Covalent, (d) Ionic.

Step-by-step solution

Understanding Ionic Bonds

Compounds with ionic bonds are usually formed between metals and nonmetals. In these compounds, metals lose electrons to become positively charged cations, while nonmetals gain electrons to become negatively charged anions.

Understanding Covalent Bonds

Covalent bonds are typically formed between nonmetal atoms. In these bonds, the atoms share electrons to achieve a full outer electron shell.

Analyze Zinc Bromide (ZnBr)

Zinc (Zn) is a metal, and bromine (Br) is a non-metal. The bonding between zinc and bromine in zinc bromide will be ionic, as zinc donates electrons to bromine.

Analyze Carbon Dioxide (CO)

Carbon (C) and oxygen (O) are both nonmetals. In carbon dioxide, they share electrons, forming covalent bonds.

Analyze Iodine Heptafluoride (IF)

Iodine (I) and fluorine (F) are nonmetals. In iodine heptafluoride, electrons are shared between atoms, forming covalent bonds.

Analyze Lead(II) Sulfate (PbSO)

Lead (Pb) is a metal, sulfate (SO) is a polyatomic ion consisting of nonmetals, with sulfur and oxygen sharing electrons covalently within the sulfate. The bond between lead and sulfate is ionic.

Key concepts

Ionic Bonds

Ionic bonds are an important concept in chemistry, especially when it comes to understanding how different elements interact. These bonds typically form between metals and nonmetals. Here's how they work: metals, which have few electrons in their outer shell, tend to lose them, becoming positively charged ions, known as cations. On the other hand, nonmetals, which have nearly full outer electron shells, gain these electrons to become negatively charged ions, called anions. This transfer of electrons creates an electrostatic attraction between the oppositely charged ions, resulting in an ionic bond.

Common characteristics of ionic compounds include:

• High melting and boiling points due to strong ionic bonds.
• The ability to conduct electricity when dissolved in water, as the ions are free to move.
• Usually a crystalline solid structure.

Understanding ionic bonds is essential, as they are the foundation for compounds like zinc bromide (ZnBr₂) and lead(II) sulfate (PbSO₄), where zinc and lead transfer electrons to bromide and sulfate ions, respectively.

Covalent Bonds

Covalent bonds form when two nonmetal atoms share one or more pairs of electrons. This type of bonding allows atoms to achieve a full outer electron shell, resulting in a more stable molecule. Rather than transferring electrons as in ionic bonds, covalent bonds involve sharing, which allows multiple atoms to "cooperate" to attain chemical stability.

Here are some key features of covalent compounds:

• Lower melting and boiling points compared to ionic compounds.
• Often found in gases and liquids at room temperature.
• Do not conduct electricity, as there are no free ions or electrons.

Covalent bonds are crucial for the formation of many organic and inorganic compounds. Carbon dioxide (CO₂) and iodine heptafluoride (IF₇) are two classic examples, where carbon shares electrons with oxygen atoms and iodine shares electrons with fluorine atoms, respectively.

Metals and Nonmetals

Understanding the distinction between metals and nonmetals is fundamental in predicting the type of chemical bonds that will form. Metals, located on the left side of the periodic table, are generally conductive, malleable, and have a shiny appearance. They tend to lose electrons when forming chemical bonds, resulting in the creation of positive ions or cations. Examples include zinc (Zn) and lead (Pb).

Nonmetals, found on the right side of the periodic table, are usually non-conductive and more brittle in their solid form. They attract or gain electrons during chemical reactions, forming negative ions or anions. Examples are oxygen (O), iodine (I), and fluorine (F).

The interaction between metals and nonmetals often results in ionic bonds, as seen with zinc bromide and lead(II) sulfate. In contrast, when nonmetals bond together, covalent bonds form, exemplified by molecules like carbon dioxide and iodine heptafluoride.