Hydrocarbons are chemical compounds made entirely of hydrogen and carbon atoms. They are the main components of gasoline, natural gas, propane, and many other fuels, and they serve as essential raw materials for plastics, synthetic fibers, lubricants, and numerous household products. Although hydrocarbons are often associated with petroleum and fossil fuels, they also occur naturally in living organisms and can be produced through biological and industrial processes.
What makes hydrocarbons especially important is the versatility of carbon. Carbon atoms can form strong bonds with other carbon atoms, creating chains, branches, and rings of different sizes. These structures, combined with the number and arrangement of hydrogen atoms, determine a hydrocarbon’s physical properties, chemical behavior, and practical uses.
Understanding hydrocarbons begins with their basic structure. From there, their major types, characteristic properties, and everyday applications reveal why these compounds play such a significant role in modern life.
What are hydrocarbons made of?
Every hydrocarbon contains only two elements: carbon and hydrogen. Carbon atoms can form four covalent bonds, which are chemical bonds created when atoms share electrons. Hydrogen atoms can form one covalent bond each.
This bonding flexibility allows carbon atoms to connect in many different arrangements. A hydrocarbon may consist of a short chain containing just a few carbon atoms, a long chain containing many carbon atoms, a branched structure, or a ring. Some hydrocarbons contain only single bonds between carbon atoms, while others contain double or triple bonds.
The arrangement of atoms affects how a hydrocarbon behaves. Small molecules generally have lower boiling points than larger molecules of the same broad structural family. Double and triple bonds also influence chemical reactivity, making some hydrocarbons more likely than others to participate in particular reactions.
Methane, the main component of natural gas, illustrates the simplest possible arrangement. It contains one carbon atom bonded to four hydrogen atoms, giving it the chemical formula CH₄.
Ethane contains two carbon atoms and six hydrogen atoms, so its formula is C₂H₆. Propane contains three carbon atoms and eight hydrogen atoms, giving it the formula C₃H₈. These compounds belong to a family called alkanes, whose members contain only single bonds between carbon atoms.
As the number of carbon atoms increases, the possible structures become more varied. Compounds with the same molecular formula can sometimes have different arrangements of atoms, producing substances with different properties. These compounds are called isomers.
This structural diversity explains why hydrocarbons range from gases that disperse rapidly in air to thick liquids used as lubricants and solid materials found in certain waxes.
The main types of hydrocarbons
Chemists classify hydrocarbons according to their bonding patterns and molecular structures. The major categories include alkanes, alkenes, alkynes, and aromatic hydrocarbons. Each category has characteristic chemical features that help explain its behavior and applications.
Alkanes: Hydrocarbons with single bonds
Alkanes are saturated hydrocarbons, meaning that their carbon atoms are connected by single bonds and carry as many hydrogen atoms as their structures permit.
For open-chain alkanes, the general molecular formula is CₙH₂ₙ₊₂, where n represents the number of carbon atoms.
Common examples include methane (CH₄), ethane (C₂H₆), propane (C₃H₈), and butane (C₄H₁₀).
Methane is the primary component of most natural gas. Propane and butane are commonly used as fuels in heating equipment, outdoor cooking appliances, portable stoves, and other applications. Gasoline also contains a mixture of hydrocarbons, including compounds from the alkane family.
Alkanes are generally less reactive than alkenes and alkynes under ordinary conditions because their carbon-carbon single bonds are relatively stable. However, they can react readily under suitable conditions. Burning an alkane in sufficient oxygen produces carbon dioxide and water while releasing energy.
The size and shape of an alkane influence its physical properties. Small alkanes are gases at room temperature, many medium-sized members are liquids, and sufficiently large members can be waxy solids. These are broad trends rather than universal boundaries because branching and molecular structure also affect melting and boiling points.
Alkenes: Hydrocarbons with double bonds
Alkenes contain at least one carbon-carbon double bond. This feature makes them unsaturated hydrocarbons because they do not carry the maximum possible number of hydrogen atoms for an open-chain structure with the same number of carbon atoms.
For a simple open-chain alkene containing one double bond and no rings, the general formula is CₙH₂ₙ.
Ethene, also known as ethylene, has the formula C₂H₄. Propene, also called propylene, has the formula C₃H₆.
The double bond gives alkenes distinctive chemical behavior. They can undergo addition reactions, in which atoms or groups of atoms attach to the carbon atoms involved in the double bond. These reactions allow manufacturers to transform relatively small hydrocarbon molecules into larger and more complex substances.
Ethene is particularly important in the production of polyethylene, one of the world’s most widely used plastics. Propene is used to manufacture polypropylene, which appears in food containers, packaging, household goods, and many other products.
Some plants also produce ethene as a signaling molecule involved in fruit ripening. Although ethene is a hydrocarbon, its biological role depends on how living tissues produce and respond to it.
Alkynes: Hydrocarbons with triple bonds
Alkynes contain at least one carbon-carbon triple bond. Like alkenes, they are unsaturated hydrocarbons, but the triple bond gives them a different structure and pattern of chemical reactivity.
For a simple open-chain alkyne containing one triple bond, the general formula is CₙH₂ₙ₋₂.
The best-known example is ethyne, commonly called acetylene, with the formula C₂H₂.
Acetylene burns in oxygen at a very high temperature, making it useful in oxyacetylene torches for cutting and welding metals. Its ability to release substantial heat during combustion makes it valuable for specialized industrial work.
Alkynes are generally less common in everyday consumer products than alkanes and alkenes. Nevertheless, they are important in chemical manufacturing, where their reactive triple bonds can serve as starting points for producing other compounds.
Aromatic hydrocarbons: Stable ring structures
Aromatic hydrocarbons contain one or more aromatic ring systems. The simplest and most familiar example is benzene, which has the formula C₆H₆.
Benzene is often represented as a six-carbon ring with alternating single and double bonds. This drawing is a simplified representation: in the actual molecule, the electrons associated with the ring’s bonding are delocalized, meaning they are spread across the ring rather than confined to separate double bonds.
This delocalization gives benzene unusual stability compared with what a simple alternating-bond picture might suggest. It also contributes to the characteristic chemical reactions of aromatic compounds.
Other important aromatic hydrocarbons include toluene and the xylene isomers. These compounds are used as industrial solvents and as raw materials in chemical manufacturing.
Aromatic hydrocarbons occur in petroleum and may be present in gasoline. However, their uses require careful management because some members of this family pose serious health hazards. Benzene, for example, is a known human carcinogen and can damage the blood-forming system.
The term aromatic has a historical origin and does not mean that every aromatic hydrocarbon has a pleasant smell. It refers to a particular kind of chemical structure and bonding.
The physical properties of hydrocarbons
Although all hydrocarbons contain only carbon and hydrogen, they can differ considerably in their appearance, state of matter, volatility, density, and other physical properties. Molecular size and structure are among the most important factors responsible for these differences.
State of matter and molecular size
Hydrocarbons occur as gases, liquids, and solids at ordinary temperatures, depending largely on the size and structure of their molecules.
Methane, ethane, propane, and butane are gases at typical room temperature and atmospheric pressure. Gasoline-range hydrocarbons are mostly liquids under ordinary conditions, while much larger hydrocarbon molecules can form oils, waxes, and other solids.
The general trend is that larger hydrocarbon molecules have higher boiling points. Larger molecules have more electrons and generally experience stronger London dispersion forces, a type of intermolecular attraction caused by temporary changes in electron distribution.
These forces must be overcome when a liquid boils. Stronger attractions usually mean that more energy is needed to separate the molecules, raising the boiling point.
Molecular shape matters as well. For example, branching can change how effectively molecules interact with one another. As a result, two hydrocarbons with the same molecular formula can have different boiling points.
Volatility and evaporation
Volatility describes how readily a substance enters the gas phase. Many small hydrocarbons are highly volatile, meaning they evaporate easily under ordinary conditions.
Gasoline contains a mixture of hydrocarbons with different boiling points, allowing some components to evaporate more readily than others. This volatility helps fuel mix with air in an engine, where it can be ignited.
However, hydrocarbon vapors can also create hazards. Many are flammable, and some can contribute to air pollution. Evaporating gasoline releases volatile organic compounds, or VOCs, that can participate in chemical reactions in the atmosphere.
The term VOC covers a broad range of carbon-containing compounds, not just hydrocarbons. Some VOCs contribute to the formation of ground-level ozone when they react with nitrogen oxides in sunlight.
Solubility in water
Most hydrocarbons are nonpolar, meaning their electrical charge is distributed relatively evenly across their molecules. Water, by contrast, is polar, with a partial negative charge near its oxygen atom and partial positive charges near its hydrogen atoms.
Because water molecules attract one another strongly through hydrogen bonding, they generally do not mix well with nonpolar hydrocarbons. This is why gasoline and cooking oil do not dissolve readily in water.
The principle that substances with similar intermolecular characteristics tend to mix is often summarized as “like dissolves like.” It is a useful guideline, although the actual solubility of any substance depends on several factors.
Many hydrocarbons dissolve readily in nonpolar or relatively nonpolar organic solvents. This property makes certain hydrocarbons useful in industrial cleaning, extraction, and manufacturing.
Their poor water solubility also has environmental consequences. When petroleum enters a lake, river, or ocean, it can form a separate layer or disperse into droplets rather than dissolving uniformly. Some components may evaporate, some may dissolve to a limited extent, and others may persist in sediments or on shorelines.
Density and appearance
Many common liquid hydrocarbons are less dense than water, which helps explain why petroleum products often float when spilled on water. However, this is a general trend, not a rule that applies to every hydrocarbon.
Pure hydrocarbons are often colorless, although commercial petroleum products can contain mixtures and impurities that give them distinctive colors or odors. Their appearance alone does not reliably identify their composition or determine whether they are safe.
Some hydrocarbons are nearly odorless. Others have recognizable smells, and commercial fuels may contain added odorants to make leaks easier to detect. For example, natural gas supplied to many homes is odorized because methane itself has no distinctive smell.
The chemical properties of hydrocarbons
Hydrocarbons are important not only because of their physical characteristics but also because of the chemical reactions they undergo. Their reactions can release energy, produce useful materials, or generate pollutants, depending on the conditions.
Combustion and energy release
Combustion is a chemical reaction in which a substance reacts with an oxidizer, usually oxygen, releasing energy. Hydrocarbons are widely used as fuels because their combustion can produce substantial amounts of heat.
During complete combustion, a hydrocarbon reacts with sufficient oxygen to produce carbon dioxide and water. For methane, the balanced chemical equation is:
CH₄ + 2O₂ → CO₂ + 2H₂O + energy
The reaction releases energy because the formation of the products involves the creation of strong chemical bonds, resulting in an overall decrease in chemical energy.
In a natural gas furnace, stove, or power plant, the released heat can be used directly or converted into another form of energy.
Complete combustion requires adequate oxygen and suitable reaction conditions. If oxygen is limited or mixing is poor, incomplete combustion can occur. Depending on the conditions, this may produce carbon monoxide, soot, and other partially oxidized compounds.
Carbon monoxide is particularly dangerous because it is colorless and odorless and interferes with the blood’s ability to transport oxygen. Properly installed and maintained combustion appliances, adequate ventilation, and working carbon monoxide alarms help reduce the risk of exposure.
Addition reactions and polymer formation
Alkenes and alkynes can undergo addition reactions because their multiple bonds provide reactive sites.
One important example is polymerization, a process in which many small molecules called monomers chemically join to form a much larger molecule called a polymer.
In addition polymerization, an alkene’s carbon-carbon double bond can open to form new bonds with neighboring units. When many ethene molecules join together, they form polyethylene.
The simplified relationship is:
nCH₂=CH₂ → (–CH₂–CH₂–)ₙ
Here, n represents a large number of repeating units.
Polyethylene is used in bags, bottles, films, pipes, and many other products. Similar reactions produce polypropylene and several other important plastics.
This connection between hydrocarbon chemistry and polymer manufacturing helps explain why small molecules obtained from petroleum or natural gas can become materials with very different physical properties.
Substitution reactions
Alkanes can undergo substitution reactions in which one atom is replaced by another atom or group of atoms. A familiar example is the reaction of methane with chlorine under ultraviolet light.
In this process, light can initiate a chain reaction that substitutes chlorine atoms for hydrogen atoms. The reaction may produce chloromethane and, with further substitution, other chlorinated products.
Such reactions illustrate that alkanes are not chemically inert. Although their carbon-carbon and carbon-hydrogen single bonds are relatively stable, suitable conditions can initiate reactions that change their composition.
Substitution reactions also demonstrate why the products of a chemical reaction depend on more than the starting materials. Light intensity, temperature, reactant proportions, and reaction pathways can influence the mixture of products formed.
Everyday examples of hydrocarbons
Hydrocarbons are found in many familiar products, often as mixtures rather than isolated chemical compounds. Their applications depend on properties such as energy content, volatility, viscosity, and ability to serve as raw materials for other chemicals.
Gasoline and diesel fuel
Gasoline is a blend of many hydrocarbons, primarily in the range of relatively small to medium-sized molecules. Its composition is adjusted to provide suitable performance in spark-ignition engines.
Diesel fuel also contains a mixture of hydrocarbons, generally with a different distribution of molecular sizes and properties. Diesel engines ignite fuel through the heat produced by compressing air, rather than relying on a spark plug to initiate combustion as in a typical gasoline engine.
Both fuels release chemical energy when their hydrocarbons react with oxygen. However, combustion also produces carbon dioxide, and real engines can emit nitrogen oxides, particulate matter, and other pollutants depending on operating conditions and emission controls.
Natural gas and propane
Natural gas consists primarily of methane, although its exact composition varies by source and processing. It is used for home heating, cooking, industrial processes, and electricity generation.
Propane is a three-carbon alkane that can be stored as a liquid under moderate pressure. When released from a pressurized container, it vaporizes and can be burned as a fuel.
Propane is used in outdoor grills, portable heaters, some residential heating systems, and equipment in locations without a natural gas connection. Butane, another small alkane, is used in some lighter fuels and portable gas appliances.
Because these fuels can form flammable mixtures with air, leaks can create fire or explosion hazards. Methane and propane can also displace oxygen in confined spaces, creating an asphyxiation risk. Safe storage, proper ventilation, and equipment designed for the specific fuel are essential.
Plastics and synthetic fibers
Many plastics begin with hydrocarbons or compounds derived from them. Ethene and propene, for example, are key starting materials for polyethylene and polypropylene.
Other hydrocarbon-derived chemicals are used to produce polyester fibers, nylon, synthetic rubber, coatings, adhesives, and numerous industrial materials. These products are not necessarily hydrocarbons themselves because their final chemical structures may contain oxygen, nitrogen, chlorine, or other elements.
Synthetic textiles illustrate this distinction. Some fibers are made from polymers whose production depends on hydrocarbon feedstocks, but the finished materials have chemical structures more complex than those of hydrocarbons alone.
Hydrocarbon chemistry therefore supports a wide range of materials whose properties can be tailored for strength, flexibility, heat resistance, durability, or other requirements.
Lubricants and waxes
Lubricating oils often contain mixtures of relatively large hydrocarbons. Their viscosity allows them to form films between moving surfaces, reducing direct contact, friction, and wear.
Engine oils and industrial lubricants may also contain additives that improve performance or protect equipment. As a result, the properties of a finished lubricant depend on more than its hydrocarbon base.
Paraffin wax is another familiar material derived from petroleum refining. It consists mainly of larger saturated hydrocarbons and is used in candles, protective coatings, packaging, and various household products.
The molecular size of these compounds helps explain their physical form. Compared with small gaseous hydrocarbons, large molecules tend to have stronger intermolecular attractions and lower volatility, making them more suitable for applications requiring a persistent coating or solid material.
Household solvents and cleaning products
Some hydrocarbon mixtures are used as solvents because they can dissolve oils, grease, and other nonpolar substances. Certain petroleum-derived solvents have applications in manufacturing, maintenance, and specialized cleaning.
However, not every household cleaner contains hydrocarbons, and not every hydrocarbon solvent is appropriate for home use. Some are highly flammable, and inhaling their vapors can cause harmful effects.
Product labels and safety instructions matter because hydrocarbon mixtures differ in composition, volatility, toxicity, and intended application. A substance’s ability to dissolve grease does not automatically make it safe for use on skin, food-contact surfaces, or enclosed indoor spaces.
Where hydrocarbons come from
Hydrocarbons have several natural and industrial sources. The most widely used supplies come from petroleum and natural gas, but biological processes also produce hydrocarbons in the environment.
Petroleum and natural gas
Petroleum and natural gas formed through complex geological processes involving organic matter buried in sediments over long periods. Heat, pressure, and chemical transformations altered this material, producing mixtures of hydrocarbons and other compounds.
Petroleum is a liquid mixture containing hydrocarbons across a wide range of molecular sizes and structures. Natural gas consists mainly of gaseous hydrocarbons, especially methane, although other gases and impurities may also be present.
After extraction, these resources undergo processing to separate useful components and remove unwanted substances. Petroleum refineries use methods such as fractional distillation, which separates components according to differences in boiling points.
Additional refining processes can change the size or structure of hydrocarbon molecules, helping produce fuels and chemical feedstocks with desired properties.
The resulting products include gasoline, diesel, jet fuel, heating oil, lubricants, and materials used by the chemical industry.
Hydrocarbons in living organisms
Hydrocarbons are not limited to fossil fuels. Some living organisms produce them naturally.
Plants can release small amounts of hydrocarbons and related volatile compounds into the atmosphere. Certain marine organisms, bacteria, and other microorganisms also produce hydrocarbons through biological processes.
Waxes and protective surface coatings on plants may contain long-chain hydrocarbon compounds that help limit water loss. Some insects use hydrocarbon mixtures on their outer surfaces as part of their chemical communication systems or as protective coatings.
These biological examples show that hydrocarbon production is not exclusively a geological or industrial process. Carbon-based chemistry is fundamental to life, and some organisms make compounds composed entirely of carbon and hydrogen for specific biological purposes.
Alternative ways to produce hydrocarbons
Hydrocarbons can also be produced from sources other than conventional petroleum and natural gas.
For example, biomass can be converted into fuels or chemical feedstocks through processes that break down or transform organic material. Some of these routes produce hydrocarbon mixtures that can be further processed into usable fuels.
Industrial processes can also synthesize hydrocarbons from carbon monoxide and hydrogen. Depending on the process and operating conditions, these reactions can produce a range of hydrocarbon molecules.
The environmental impact of these alternatives depends on how the feedstocks are obtained, how much energy the production process consumes, what energy sources are used, and how the final products are handled. A fuel made from a non-fossil feedstock is not automatically low-carbon across its entire life cycle.
Hydrocarbons and the environment
Hydrocarbons have enabled transportation, heating, electricity generation, and large-scale chemical manufacturing. Their production and use also create environmental challenges, particularly when fuels are burned or petroleum products enter natural ecosystems.
Greenhouse gas emissions
When hydrocarbons are burned completely, their carbon atoms are converted mainly into carbon dioxide. Carbon dioxide absorbs infrared radiation and contributes to the greenhouse effect, which warms Earth’s surface and lower atmosphere.
The climate impact of fossil fuels includes more than the carbon dioxide produced at the point of combustion. Extracting, processing, and transporting fuels can also release greenhouse gases.
Methane deserves particular attention because it is a potent greenhouse gas. Leaks from natural gas systems, coal production, landfills, agriculture, and other sources can add methane to the atmosphere. Methane released during fossil fuel production may contribute to climate change even before the fuel is burned.
Reducing greenhouse gas emissions therefore involves both limiting carbon dioxide from fuel use and preventing avoidable methane leaks. The relative benefits of different energy sources depend on their full life-cycle emissions and how they are used.
Air pollution from combustion
Burning hydrocarbons can produce pollutants in addition to carbon dioxide and water.
Incomplete combustion can generate carbon monoxide and particulate matter. High-temperature combustion can also cause nitrogen in the air to react with oxygen, forming nitrogen oxides. These pollutants contribute to health problems and environmental damage.
In the atmosphere, nitrogen oxides and certain VOCs can react in sunlight to produce ground-level ozone, a major component of smog. Ozone near the ground can irritate the respiratory system and damage vegetation.
The amount and type of pollution depend on the fuel, combustion conditions, engine or appliance design, and pollution-control technology. Properly maintained equipment and effective emission controls can reduce many of these pollutants, although they do not eliminate every environmental impact.
Oil spills and contamination
When petroleum enters water or soil, its effects depend on the composition of the mixture, the quantity released, environmental conditions, and the organisms exposed.
Some components evaporate relatively quickly, while others remain in the environment for longer periods. Certain hydrocarbons can be toxic to aquatic organisms, damage feathers and fur, interfere with biological functions, or contaminate sediments and shorelines.
Microorganisms can break down many hydrocarbons, but the process varies considerably by compound and environmental conditions. Oxygen availability, temperature, nutrient levels, and the physical form of the contamination can all affect how quickly degradation occurs.
Oil spills may therefore require physical removal, containment, or other remediation measures. Natural breakdown can help reduce contamination, but it does not guarantee that an affected ecosystem will recover quickly or completely.
Plastics and persistent waste
Hydrocarbon-derived polymers have practical advantages, including low weight, durability, and resistance to many forms of degradation. Those same properties can create waste-management challenges when products are discarded carelessly.
Plastic pollution occurs when plastic materials accumulate in terrestrial and aquatic environments. Larger items can fragment into smaller pieces, including microplastics, while some plastics persist for long periods.
Not all plastic is made exclusively of hydrocarbons, and the environmental behavior of a plastic depends on its polymer, additives, size, and surrounding conditions. Nevertheless, many widely used plastics originate from hydrocarbon feedstocks.
Reducing unnecessary consumption, designing products for reuse, improving collection systems, and using recycling methods suited to particular materials can help limit plastic waste. The most effective approach depends on the product and the available waste-management infrastructure.
Are hydrocarbons dangerous?
Hydrocarbons vary greatly in their hazards. Some are widely used fuels when handled correctly, while others can cause serious health effects through inhalation, skin contact, ingestion, or environmental exposure.
Flammability is one of the most important shared hazards among many common hydrocarbons. When vapor concentrations fall within a combustible range and an ignition source is present, a fire or explosion can occur. Liquefied petroleum gases can also cause cold burns if rapidly released liquid contacts the skin.
Inhalation risks differ by compound. High concentrations of gases such as methane can displace oxygen in enclosed spaces, causing suffocation. Some liquid hydrocarbon vapors can irritate the respiratory system or affect the nervous system. Benzene is a well-established carcinogen, whereas the health effects of other hydrocarbons depend on their particular chemical structures and exposure levels.
Swallowing certain petroleum products can be especially dangerous because liquid can enter the lungs during swallowing or vomiting, causing chemical lung injury. Suspected poisoning or significant exposure requires prompt advice from a medical professional or poison control service.
Safe handling depends on the specific substance rather than the general label hydrocarbon. Ventilation, suitable storage containers, ignition control, protective equipment, and compliance with product instructions are important safeguards.
How hydrocarbons differ from other organic compounds
Hydrocarbons are part of a much larger group of substances called organic compounds. In modern chemistry, organic compounds are generally understood as carbon-based compounds, although some carbon-containing substances, such as carbon dioxide and carbonates, are classified as inorganic.
The defining feature of a hydrocarbon is that it contains only carbon and hydrogen. Many other organic compounds contain additional elements, including oxygen, nitrogen, sulfur, phosphorus, or halogens such as chlorine.
For example, ethanol contains carbon, hydrogen, and oxygen, so it is an alcohol rather than a hydrocarbon. Acetic acid, the acid responsible for vinegar’s characteristic acidity, also contains oxygen and is not a hydrocarbon.
This distinction matters when comparing chemical properties. Adding oxygen or other elements can change a compound’s polarity, solubility, acidity, reactivity, and biological effects.
Hydrocarbon molecules are often relatively nonpolar, but their derivatives may interact strongly with water or participate in reactions unavailable to the original hydrocarbon. The transformation of hydrocarbons into more complex organic chemicals is therefore central to both industrial chemistry and biological processes.
Why the structure of a hydrocarbon matters
Hydrocarbons demonstrate how a small number of elements can produce a remarkable variety of substances. Their properties arise from the number of carbon atoms, the arrangement of those atoms, the types of bonds between them, and the forces acting between separate molecules.
A short, saturated hydrocarbon such as methane is a gas under ordinary conditions and serves as a major fuel. An unsaturated hydrocarbon such as ethene can undergo polymerization to form plastic. An aromatic hydrocarbon such as benzene has a distinctive ring structure and serves as an important industrial chemical, although its health hazards restrict safe use.
Larger hydrocarbons can form liquids used in fuels and lubricants or solids used in waxes and coatings. Their low water solubility helps explain why petroleum does not mix readily with water, while their carbon content explains why combustion releases carbon dioxide.
These connections reveal the central principle of hydrocarbon chemistry: the arrangement of atoms determines a molecule’s properties, and those properties determine how the molecule behaves and how people can use it. Understanding that relationship helps explain the role of hydrocarbons in energy, manufacturing, household products, living systems, and environmental change.
