What are the physical properties of alkenes?

Alkenes are unsaturated hydrocarbons that are colourless, odourless, and less dense than water.

Alkenes are a type of hydrocarbon, which means they are composed of hydrogen and carbon atoms. They are unsaturated, meaning they contain at least one carbon-carbon double bond. This double bond gives alkenes their unique properties and distinguishes them from other types of hydrocarbons like alkanes and alkynes.

Physically, alkenes are typically colourless and odourless, making them difficult to detect without chemical testing. They are less dense than water, which means they will float if mixed with it. This property is useful in oil spills, where alkenes (in the form of petroleum) can be seen floating on the surface of bodies of water.

Alkenes are also insoluble in water but soluble in organic solvents. This is due to the fact that water is a polar molecule, while alkenes are nonpolar. Polar and nonpolar substances generally do not mix well together, which is why alkenes do not dissolve in water. However, they do dissolve in organic solvents, which are also nonpolar.

The boiling points of alkenes are relatively low and increase with the size (number of carbon atoms) of the molecule. This is because larger molecules have more electrons and thus stronger London dispersion forces (a type of intermolecular force), which require more energy (heat) to overcome.

In terms of reactivity, the carbon-carbon double bond in alkenes makes them more reactive than alkanes. This is because the double bond is a region of high electron density, which can easily be attacked by electrophiles (electron-loving species). This makes alkenes very important in chemical reactions, particularly in the field of organic chemistry.