What Is Chemistry?
Chemistry is the
study of matter, its properties, how and why substances combine or separate to
form other substances, and how substances interact with energy. Many people
think of chemists as being white-coated scientists mixing strange liquids in a
laboratory, but the truth is we are all chemists. Understanding basic chemistry
concepts is important for almost every profession. Chemistry is part of
everything in our lives.
Every material in existence is made up of matter — even our
own bodies. Chemistry is involved in everything we do, from growing and cooking
food to cleaning our homes and bodies to launching a space shuttle. Chemistry
is one of the physical sciences that help us to describe and explain our world.
Five
branches
There are five main branches of chemistry, each of which has many areas of study.
Analytical
chemistry uses qualitative and quantitative observation to identify and
measure the physical and chemical properties of substances. In a sense, all
chemistry is analytical.
Physical
chemistry combines chemistry with physics. Physical chemists study how
matter and energy interact. Thermodynamics and quantum mechanics are two of the
important branches of physical chemistry.
Organic
chemistry specifically studies compounds that contain the element
carbon. Carbon has many unique properties that allow it to form complex
chemical bonds and very large molecules. Organic chemistry is known as the
“Chemistry of Life” because all of the molecules that make up living tissue
have carbon as part of their makeup.
Inorganic
chemistry studies materials such as metals and gases that do not have
carbon as part of their makeup.
Biochemistry
is the study of chemical processes that occur within living organisms.
Fields of study
Within these broad categories are countless fields of study,
many of which have important effects on our daily life. Chemists improve many
products, from the food we eat and the clothing we wear to the materials with
which we build our homes. Chemistry helps to protect our environment and
searches for new sources of energy.
Food
chemistry
Food science deals with the three biological components of
food — carbohydrates, lipids and proteins. Carbohydrates are sugars and
starches, the chemical fuels needed for our cells to function. Lipids are fats
and oils and are essential parts of cell membranes and to lubricate and cushion
organs within the body. Because fats have 2.25 times the energy per gram than
either carbohydrates or proteins, many people try to limit their intake to
avoid becoming overweight. Proteins are complex molecules composed of from 100
to 500 or more amino acids that are chained together and folded into
three-dimensional shapes necessary for the structure and function of every
cell. Our bodies can synthesize some of the amino acids; however eight of them,
the essential amino acids, must be taken in as part of our food. Food
scientists are also concerned with the inorganic components of food such as its
water content, minerals, vitamins and enzymes.
Food chemists improve the quality, safety, storage and taste
of our food. Food chemists may work for private industry to develop new
products or improve processing. They may also work for government agencies such
as the Food and Drug Administration to inspect food products and handlers to
protect us from contamination or harmful practices. Food chemists test products
to supply information used for the nutrition labels or to determine how
packaging and storage affects the safety and quality of the food. Flavorists work
with chemicals to change the taste of food. Chemists may also work on other
ways to improve sensory appeal, such as enhancing color, odor or texture.
Environmental
chemistry
Environmental chemists study how chemicals interact with the
natural environment. Environmental chemistry is an interdisciplinary study that
involves both analytical chemistry and an understanding of environmental
science. Environmental chemists must first understand the chemicals and
chemical reactions present in natural processes in the soil water and air.
Sampling and analysis can then determine if human activities have contaminated
the environment or caused harmful reactions to affect it.
Water quality is an important area of environmental
chemistry. “Pure” water does not exist in nature; it always has some minerals
or other substance dissolved in it. Water quality chemists test rivers, lakes
and ocean water for characteristics such as dissolved oxygen, salinity,
turbidity, suspended sediments, and pH. Water destined for human consumption
must be free of harmful contaminants and may be treated with additives like
fluoride and chlorine to increase its safety.
Agricultural
chemistry
Agricultural chemistry is concerned with the substances and
chemical reactions that are involved with the production, protection and use of
crops and livestock. It is a highly interdisciplinary field that relies on ties
to many other sciences. Agricultural chemists may work with the Department of
Agriculture, the Environmental Protection Agency, the Food and Drug
Administration or for private industry. Agricultural chemists develop
fertilizers, insecticides and herbicides necessary for large-scale crop
production. They must also monitor how these products are used and their
impacts on the environment. Nutritional supplements are developed to increase
the productivity of meat and dairy herds.
Agricultural biotechnology is a fast-growing focus for many
agricultural chemists. Genetically manipulating crops to be resistant to the
herbicides used to control weeds in the fields requires detailed understanding
of both the plants and the chemicals at the molecular level. Biochemists must
understand genetics, chemistry and business needs to develop crops that are
easier to transport or that have a longer shelf life.
Chemical
engineering
Chemical engineers research and develop new materials or
processes that involve chemical reactions. Chemical engineering combines a
background in chemistry with engineering and economics concepts to solve
technological problems. Chemical engineering jobs fall into two main groups:
industrial applications and development of new products.
Industries require chemical engineers to devise new ways to
make the manufacturing of their products easier and more cost effective.
Chemical engineers are involved in designing and operating processing plants,
develop safety procedures for handling dangerous materials, and supervise the
manufacture of nearly every product we use. Chemical engineers work to develop
new products and processes in every field from pharmaceuticals to fuels and
computer components.
Geochemistry
Geochemists combine chemistry and geology to study the
makeup and interaction between substances found in the Earth. Geochemists may
spend more time in field studies than other types of chemists. Many work for
the U.S. Geological Survey or the Environmental Protection Agency in
determining how mining operations and waste can affect water quality and the
environment. They may travel to remote abandoned mines to collect samples and
perform rough field evaluations, and then follow a stream through its watershed
to evaluate how contaminants are moving through the system. Petroleum
geochemists are employed by oil and gas companies to help find new energy
reserves. They may also work on pipelines and oil rigs to prevent chemical
reactions that could cause explosions or spills.
Forensic
chemistry
Forensic chemists capture and analyze the physical evidence
left behind at a crime scene to help determine the identities of the people
involved as well as to answer other vital questions regarding how and why the
crime was carried out. Forensic chemists use a wide variety of analyzation
methods, such as chromatography, spectrometry and spectroscopy.
In new research appearing in the Journal of the American
Society of Mass Spectrometry, scientists from the department of chemistry at Louisiana State University (LSU) set
out to apply laser technology to the field of forensic science.
They developed a system that goes above and beyond the
identification of a fingerprint. The technique can capture molecules contained
within a fingermark, including lipids, proteins, genetic material, or even
trace amounts of explosives, which can be further analyzed. The new tool
essentially takes the mystery out of identifying the chemical composition of
fingermarks at crime scenes.
The tool focuses a laser — using mirrors and optical fibers — onto a surface containing a
fingermark. The laser then heats up any water or moisture on the surface,
triggering chemical bonds in the water to stretch and vibrate, according to the
LSU College of Science Blog. All of this focused energy causes the water to “explode,” turning it into a gas and
separating biomolecules such as DNA. This process is called laser ablation.
Next a small vacuum pump system pulls the water and
molecules into a tiny filter that captures everything left behind by a person’s
finger. Forensic scientists can then put the contents into an analysis device
such as a mass spectrometer or a gas chromatography-mass spectrometer.
Importantly, this laser ablation technique can easily capture
fingermarks on porous surfaces, such as cardboard (on which traditional
forensic methods have not been very successful).
To test their new technique, the researchers placed
fingermarks on many different surface types, including glass, plastic, aluminum
and cardboard. These fingermarks were laced with substances as diverse as
caffeine, antiseptic cream, condom lubricants and TNT, according to the LSU
College of Science Blog. After each fingermark capture, the chemists were able
to identify these substances using mass spectrometry
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