Alkane

Some things are made of carbon and air.

These small pieces join together like a tree.

They can be gases. They can be liquids. They can even be hard waxes.

Most come from oil or natural gas. Some are even made by tiny living things. These small pieces are found all over our world.

Alkanes are a group of molecules made from carbon and hydrogen.

They are built like tiny trees. The carbon atoms form a backbone. This backbone can be a straight line. It can also have branches.

Some alkanes even form rings. We call these rings cycloalkanes.

These molecules change based on their size. Small alkanes are gases. For example, methane is a gas.

Medium alkanes are liquids. Large alkanes are solid waxes.

Alkanes can have the same parts but different shapes. These different shapes are called isomers. A small change in shape can make a big difference. For example, butane and isobutane are isomers. They have the same number of atoms. But their atoms are joined in different ways.

We find most alkanes in petroleum and natural gas.

Some tiny living things also make methane. This is a very simple alkane.

Alkanes are a special group of molecules made of carbon and hydrogen atoms.

Scientists call them hydrocarbons because they only contain those two elements. They are also known as saturated hydrocarbons. This means they have the maximum number of hydrogen atoms possible. Each carbon atom is linked to others by single bonds. These bonds create a structure that looks like a tiny tree.

This backbone of carbon atoms is called a carbon skeleton. Alkanes are very important in our world. They can be found in natural gas and petroleum.

How an alkane is built depends on how the atoms connect. In a simple chain, the carbons link one after another in a line. Some alkanes are branched, meaning a chain sticks out from the main line.

You can also find cycloalkanes, where the atoms form one or more rings.

Even with the same atoms, the shape can change. These different shapes are called structural isomers. For example, butane and isobutane both have four carbons. However, their atoms are arranged in different patterns. As you add more carbons, the number of possible shapes grows very fast.

People have studied these molecules for a long time. In 1866, a scientist named August Wilhelm von Hofmann helped create a system for naming them. He suggested using different endings based on the types of bonds present. Today, the International Union of Pure and Applied Chemistry, or IUPAC, sets the official rules. These rules use Greek prefixes to tell us how many carbons are in a molecule. For example, "meth-" means one carbon, and "eth-" means two. This system helps scientists all over the world talk about the same thing. It makes studying complex chemistry much easier.

There are many specific facts about the alkane family. Methane is the simplest alkane and has only one carbon.

It is a gas at normal temperatures. As the molecules get larger, they change their physical state. Small alkanes like propane are gases. Medium ones like hexane are liquids.

The largest alkanes, with more than 17 carbons, are solid waxes.

Some alkanes are even made by tiny living things called methanogenic archaea.

These tiny organisms produce methane as part of their life.

You can see the effects of alkanes in many places. Most of the fuel we use comes from these molecules. We find them in the crude oil pulled from deep underground.

Some plants and fungi use long-chain alkanes as protective waxes. Certain animals even use them as pheromones to communicate. You might recognize the smell of propane or butane from a kitchen stove. Even the gas on the planet Jupiter is mostly methane.

These molecules are truly a part of our daily lives.

Alkanes are a fundamental class of organic compounds known as acyclic saturated hydrocarbons.

This means they consist entirely of carbon and hydrogen atoms. In an alkane, every carbon atom is saturated with hydrogen. This occurs because the carbon atoms are joined only by single bonds. These single bonds allow each carbon to hold the maximum number of hydrogen atoms possible. The International Union of Pure and Applied Chemistry (IUPAC) defines them as unbranched or branched chains. Some scientists also use the term to include cycloalkanes, which are molecules where the atoms form rings.

To understand how an alkane is built, we must look at its molecular structure. Each carbon atom in an alkane is sp3-hybridized. This specific type of orbital hybridization results in four sigma bonds for every carbon. These bonds can connect to other carbon atoms or to hydrogen atoms. The longest continuous chain of these carbon atoms is called the carbon backbone or skeleton.

All alkanes belong to a homologous series. This means they follow a repeating pattern of methylene units, or -CH2- groups. Because of this pattern, each member of the series differs from the next by a molecular mass of 14.03 u. This mass comes from one carbon atom and two hydrogen atoms.

Alkanes can exist in several different structural forms. The simplest form is a linear chain, often called an n-isomer. However, the carbon backbone can also branch out to create different shapes. These different arrangements of the same atoms are called structural isomers. For example, C4H10 can exist as both butane and isobutane. As the number of carbon atoms increases, the number of possible isomers grows rapidly. A molecule with 10 carbons has 75 possible isomers. By the time you reach 60 carbons, there are over 22 sextillion possible arrangements.

Beyond linear and branched chains, there are cycloalkanes. These are hydrocarbons where the carbon atoms are joined in one or more rings. While some sources group them with alkanes, they have a different general formula. For instance, a cycloalkane with five carbons has the formula C5H10, whereas a straight-chain pentane is C5H12.

There are also branched alkanes that can be chiral. This means they have a specific spatial arrangement that makes them non-superimposable on their mirror images. An example is 3-methylhexane, which has a stereogenic center at the third carbon atom.

Scientists have developed specific systems to name these complex molecules. In 1866, August Wilhelm von Hofmann suggested a system using vowel suffixes. He used -ane, -ene, -ine, -one, and -une to distinguish different types of hydrocarbons. Modern IUPAC nomenclature has refined this. We now use Greek prefixes to indicate the number of carbon atoms. For example, "meth-" is for one carbon and "eth-" is for two. To name a branched molecule, you must find the longest continuous carbon chain first. Then, you identify and number the side chains, which are called alkyl groups.

Physical properties of alkanes change based on their molecular weight. All alkanes are colorless. Small alkanes with low molecular weights, like methane, are gases at standard temperature and pressure.

As the carbon chain gets longer, the molecules become liquids. For example, octane is a liquid. Once the carbon backbone exceeds about 17 atoms, the alkanes become solid waxes. These heavier alkanes are used for various industrial and natural purposes.

Alkanes are highly significant in both nature and industry. Most of our commercial alkanes come from petroleum or natural gas.

In the biological world, methane is produced by tiny organisms called methanogenic archaea.

Some long-chain alkanes serve as protective waxes for plants and fungi. Certain animals even use these molecules as pheromones for communication. Even in space, alkanes are present; methane is a major component of the atmosphere on Jupiter.