2.2.5. Properties of Covalent Compounds

Covalent compounds usually have lower melting and boiling points compared to ionic compounds. They can exist in various physical states (gases, liquids, or solids) at room temperature. Additionally, they are poor conductors of electricity.

Covalent compounds are formed through the sharing of electrons between non-metal atoms. The bonds in these compounds are typically weaker than ionic bonds, leading to lower melting and boiling points. This means that covalent compounds can be found in different physical states at room temperature, such as gases (like oxygen), liquids (like water), or solids (like sugar). These compounds do not conduct electricity because there are no free-moving ions or charged particles in their structure.

Think of covalent compounds like a cozy group of friends who share resources (electrons) equally. They can form small gatherings (gases) or have big parties (solids), and they don’t make a lot of noise (poor conductors), staying under the radar unless there’s an actual reaction taking place.

Covalent compounds generally have lower melting and boiling points than ionic compounds.

The lower melting and boiling points of covalent compounds can be attributed to the weak forces holding the molecules together, known as Van der Waals forces. Unlike ionic compounds, which are held together by strong electrostatic forces between ions, covalent compounds require less energy to break these weaker interactions, hence they can change states (from solid to liquid or gas) at lower temperatures.

Imagine a group of friends who form a book club (covalent bonds). If they want to disperse, they just have to agree to leave; it’s easy for them to split up. Compare this to a rigid structure like a military formation (ionic bonds) that takes time and effort to break apart—lots of shouting and orders!

Covalent compounds are generally poor conductors of electricity.

Covalent compounds do not conduct electricity because they lack charged particles that can move freely. In contrast to ionic compounds, where ions can move and carry an electric current when dissolved in water, covalent compounds are neutral and do not have free-moving charged ions. This is why they do not conduct electricity in solid form, or when dissolved in water.

Think of a covalent compound as a crowd at a concert who are all standing still (like a solid). Even though there are people (molecules) in the crowd, they can’t move freely through the crowd to create a pathway (conduct electricity). In a contrast, if those people were instructed to form a line and move to the exits quickly (the ions in ionic compounds), they would be able to 'conduct' themselves to safety.

Covalent compounds can often exist as gases, liquids, or solids at room temperature.

The physical state of a covalent compound at room temperature depends on the strength of the interactions between the molecules. Stronger intermolecular forces can lead to a solid state, while weaker forces result in liquid or gas states. For example, water (H₂O) is a liquid due to the hydrogen bonds between the molecules, while carbon dioxide (CO₂) is a gas at room temperature due to its weak van der Waals forces.

Picture three types of parties based on different themes: the quiet book reading session (solid), where everyone sits close together; the coffee catch-up (liquid), where people are mingling but aren’t as tightly packed; and the wild dance party (gas), where everyone is spread out and moving around freely. The bond strength and temperature of compounds determine the 'party' they are at—this helps to visualize why some compounds are solid, liquid, or gas at the same temperature.

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