Properties of Covalent Compounds
Molecular substances have low melting points and rarely conduct.
About this topic
Simple molecular covalent compounds have strong bonds within molecules but weak forces between them, so they typically have low melting and boiling points, are often gases or liquids at room temperature, and do not conduct electricity because they have no free ions or electrons. Many are insoluble in water but dissolve in organic solvents.
When a molecular substance melts or boils, only the weak intermolecular forces are overcome, not the covalent bonds, which explains the low temperatures. Without charged particles able to move, they are insulators, as with sugar, wax and plastic. Solubility follows polarity: polar molecules like ethanol and sugar dissolve in water, while nonpolar ones like oil and iodine do not, but iodine does dissolve in hexane. Larger molecules are generally solids because of stronger dispersion forces.
Compare carbon dioxide, a gas with a sublimation point of minus 78 degrees Celsius, to sodium chloride, a solid melting at 801. Candle wax softens in a flame while table salt is unaffected. Covalent compounds make fuels, plastics, medicines and perfumes.
A common error is believing that all covalent substances have low melting points; giant covalent structures such as diamond and silicon dioxide melt at very high temperatures. Also, a few molecules like hydrogen chloride conduct when dissolved because they react with water to form ions.
Key ideas
- Weak forces between molecules
- Gases, liquids or soft solids
- Network solids like diamond are hard
Quick check
Use cases: where Properties of Covalent Compounds helps
- Homework: review the key idea behind Properties of Covalent Compounds before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Properties of Covalent Compounds without notes.
- Visual learning: play with the interactive lab to see how Properties of Covalent Compounds changes when you adjust its inputs.
- Teaching a friend: explain Properties of Covalent Compounds in your own words, then compare your version with the key ideas.
Chemistry explains medicine, food, cleaning products, fuels and building materials.
Frequently asked questions
What is Properties of Covalent Compounds?
Molecular substances have low melting points and rarely conduct.
What will I learn in Properties of Covalent Compounds?
Weak forces between molecules. Gases, liquids or soft solids. Network solids like diamond are hard.
Is Properties of Covalent Compounds part of Chemistry?
Yes. It is one of 150 Chemistry topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Properties of Covalent Compounds lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Properties of Covalent Compounds?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
Do I need an account, and is my progress saved?
No account is needed. Marking a topic as learned is saved in your own browser, so it stays on that device and is not sent to a server.