Problem 19 - Biology the Easy Way (E-Z Biology)

Question

Covalent bonding occurs between atoms in (a) calcium (c) salt (b) sodium (d) water

Step-by-Step Solution

Answer

Covalent bonding occurs in (d) water.

Step 1: Understanding Covalent Bonds

Covalent bonds are formed when atoms share electrons, typically between non-metal elements. This type of bond allows atoms to achieve a full outer electron shell, resulting in a stable molecule.

Step 2: Examining the Options

Let's analyze each option: (a) Calcium: Calcium is a metal, and metals typically form ionic bonds by transferring electrons, not sharing. (b) Sodium: Sodium is also a metal, and similar to calcium, it forms ionic bonds rather than covalent bonds. (c) Salt: Salt usually refers to sodium chloride (NaCl), which is an ionic compound formed between a metal (sodium) and a non-metal (chlorine). (d) Water: Water (H₂O) consists of hydrogen and oxygen, both of which are non-metals. They share electrons to form covalent bonds.

Step 3: Identifying the Correct Answer

From our examination, only water, which is a compound of non-metals hydrogen and oxygen, forms covalent bonds by sharing electrons between atoms. Therefore, the correct answer must be water.

Key Concepts

Ionic Bonding

Ionic bonding occurs when electrons are transferred from one atom to another. This movement creates ions, which are atoms with positive or negative charges. In an ionic bond, a metal element typically loses electrons to become a positively charged ion, while a non-metal element gains those electrons, becoming a negatively charged ion.

This electrostatic attraction between the oppositely charged ions forms a strong bond. A common example of ionic bonding is found in sodium chloride (table salt). Here, the metal sodium loses one electron to become Na⁺, and the non-metal chlorine gains an electron to become Cl⁻. These ions then attract each other, resulting in the ionic compound NaCl.

• Key points about ionic bonding:
• Ions are formed through the transfer of electrons.
• Typically occurs between metals and non-metals.
• Results in strong bonds due to electrostatic forces.
• Creates compounds with distinct crystalline structures.

Electron Sharing

Electron sharing is the hallmark of covalent bonding, where pairs of electrons are shared between atoms. This sharing allows molecules to achieve the octet rule, meaning each atom has eight electrons in its outer shell, creating stability. Covalent bonds are common amongst non-metal elements.

The sharing can occur in different ways depending on the elements involved and the electrons they have available. For instance, in a water molecule (H₂O), oxygen shares electrons with two hydrogen atoms, creating a bond where each hydrogen atom satisfies its need for two electrons, and oxygen achieves a stable arrangement.

• Important insights into electron sharing:
• Occurs mainly between non-metal elements.
• Involves the sharing, not transfer, of electrons.
• Creates molecules rather than ionic compounds.
• This type of bonding results in liquid or gaseous substances at room temperature.

Non-metal Elements

Non-metal elements are crucial players in both covalent bonding and ionic compounds. They have high electronegativities, which means they have a strong attraction to electrons. Non-metals are found on the right side of the periodic table and include elements like oxygen, nitrogen, and chlorine.

In covalent bonds, non-metals readily share electrons with each other. This shared bonding leads to stable molecules and can range from simple molecules like oxygen ( ext{O}_2 ext{)} to vast networks in organic compounds. When non-metals participate in ionic bonding, they typically gain electrons from metals, forming negatively charged ions.

• Characteristics of non-metal elements:
• High electronegativity.
• Commonly found forming covalent bonds with each other.
• Act as the element accepting electrons in ionic bonds.
• They often appear as gases or brittle solids at room temperature.