Question

Some plant fertilizer compounds are \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4}, \mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}, \mathrm{~K}_{2} \mathrm{O}\), \(\mathrm{P}_{2} \mathrm{O}_{5}\), and \(\mathrm{KCl}\). Which of these compounds contain both ionic and covalent bonds?

Short answer

The compounds that contain both ionic and covalent bonds are \((\mathrm{NH}_{4})_{2} \mathrm{SO}_{4}\) and \(\mathrm{Ca}_{3}(\mathrm{PO}_{4})_{2}\). In \((\mathrm{NH}_{4})_{2} \mathrm{SO}_{4}\), covalent bonds exist between N and H atoms, and between S and O atoms, while the bond between NH4+ and SO4- groups is ionic. In \(\mathrm{Ca}_{3}(\mathrm{PO}_{4})_{2}\), covalent bonds exist between P and O atoms (within PO4 groups), and the bond between Ca and PO4 is ionic.

Step-by-step solution

Identify Metals and Non-metals in Each Compound

First, list the elements in each compound and identify whether each element is a metal or non-metal. - (NH4)2SO4: N (non-metal), H (non-metal), S (non-metal), O (non-metal) - Ca3(PO4)2: Ca (metal), P (non-metal), O (non-metal) - K2O: K (metal), O (non-metal) - P2O5: P (non-metal), O (non-metal) - KCl: K (metal), Cl (non-metal)

Check for Ionic and Covalent Bonds in Each Compound

Now that we have identified the metals and non-metals in each compound, let's analyze their bonding types: 1. (NH4)2SO4: This compound has both ionic and covalent bonds. The NH4+ (ammonium) groups have a covalent bond between N and H atoms, and the SO4- groups have a covalent bond between S and O atoms. The bond between NH4+ and SO4- is an ionic bond. 2. Ca3(PO4)2: The covalent bonds exist between P and O atoms (within PO4 groups). The bond between Ca and PO4 is an ionic bond. This compound contains both ionic and covalent bonds. 3. K2O: This compound has an ionic bond between K (metal) and O (non-metal). There are no covalent bonds in this compound. 4. P2O5: This compound has only covalent bonds between P (non-metal) and O (non-metal) atoms. 5. KCl: This compound has an ionic bond between K (metal) and Cl (non-metal). There are no covalent bonds in this compound.

Identify the Compounds with Both Ionic and Covalent Bonds

Based on our analysis, the following compounds have both ionic and covalent bonds: - (NH4)2SO4 - Ca3(PO4)2

Key concepts

Ionic Bonds

Ionic bonds are a fundamental type of chemical bond formed between metals and non-metals. They occur when one element donates an electron to another, creating ions with opposite charges that attract each other.

• The donating element, often a metal, becomes a positively charged ion (cation).
• The receiving element, usually a non-metal, becomes negatively charged (anion).

This electrostatic attraction holds the ions together in a lattice structure, typical of ionic compounds. For example, in potassium oxide ( K_2O ), potassium (K) donates electrons to oxygen (O), forming an ionic bond.
Ionic compounds generally have high melting and boiling points due to the strong attraction between ions. They are also often soluble in water and can conduct electricity when dissolved because they break into free ions that carry charge.

Covalent Bonds

Covalent bonds are another primary type of chemical bond, characterized by the sharing of electron pairs between atoms. These bonds generally form between non-metal elements.

• Instead of transferring electrons, atoms in a covalent bond share them to achieve a full outer shell.
• The shared electrons create a strong bond that holds the atoms together.

In the compound P_2O_5 , for example, phosphorus (P) and oxygen (O) atoms are bonded through covalent bonds, sharing their electrons. This sharing allows each atom to achieve stability similar to that in noble gases.
Covalent compounds can exist in different states—gas, liquid, or solid—depending on the strength of the bond and the atomic configuration. They typically have lower melting and boiling points than ionic compounds and do not conduct electricity in any state.

Compound Analysis

Analyzing compounds to identify types of bonds involves understanding the elemental composition and the nature of bonding.

• Compounds like (NH_4)_2SO_4 contain both ionic and covalent bonds.
• The bond between ammonium (NH_4+) and sulfate (SO_4-) is ionic, while the bonds within the ammonium and sulfate ions are covalent.

To analyze a compound: 1. Identify each element as a metal or non-metal. 2. Determine if there is a donation or sharing of electrons. 3. Look at the structural formula to see how atoms are connected.
By understanding these basics, one can easily discern between purely ionic compounds like KCl , purely covalent compounds like P_2O_5 , and complex ones with both types, like Ca_3(PO_4)_2 . This comprehensive understanding is vital for predicting compound behavior and reactivity.