Generally lower melting points and poor electrical conductivity, with strong bonds within molecules.
Practise Bonding & Molecular Structure All Bonding & Molecular Structure topics
Covalent compounds are usually made of discrete molecules held together by relatively weak intermolecular forces. Because these forces are weak compared with the strong bonds within the molecules, the compounds tend to have low melting and boiling points and are often gases, liquids or soft solids. They generally do not conduct electricity, since they contain no free ions or delocalized electrons. Solubility depends on polarity, with polar molecules dissolving in water and nonpolar molecules in organic solvents. Covalent network solids are a major exception, forming extremely hard, high-melting materials.
Key ideas: Distinguish two classes: simple molecular substances with low melting points and no conduction, and giant covalent networks with very high melting points. Melting trend within molecular substances follows the strength of intermolecular forces and molar mass. Test of conduction in water: acids such as HCl conduct after ionizing even though they are covalent.
Common mistakes and connections: A common error is saying covalent bonds break when a molecular substance melts or boils, when only intermolecular forces are overcome. Another is claiming all covalent compounds are insoluble in water, ignoring sugar, ethanol and ammonia. Connects to intermolecular forces, polarity, network solids and electrolytes.
Covalent molecules interact only through weak intermolecular forces, so they readily move past each other as liquids or gases at modest temperatures. The interactive lesson shows this as a live animation or chart.
Methane boils at -162 degrees Celsius because its molecules attract one another only weakly.
Generally lower melting points and poor electrical conductivity, with strong bonds within molecules.
Properties of Covalent Compounds is a beginner topic in Bonding & Molecular Structure. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in Bonding & Molecular Structure first: Lattice Energy, Born-Haber Cycle, Properties of Ionic Compounds.
The next topics in Bonding & Molecular Structure are Properties of Metals and Band Theory.
Yes. The interactive lesson includes a self-check question on Properties of Covalent Compounds, and the Bonding & Molecular Structure quiz draws on every topic in this area.
Properties of Covalent Compounds is topic 30 of 104 in Bonding & Molecular Structure.