Chemistry is a branch of natural science that deals principally with the properties of substances, the changes they undergo, and the natural laws that describe these changes. The more qualitative chemist might work on synthesizing a new compound used in medicine, for example, while the more quantitative work can seem much like physics applied to the microscopic level of atoms and molecules. Anything you can touch or smell or see contains one or more chemicals.
It is often seen as linked to the quest to turn lead or another common starting material into gold,  though in ancient times the study encompassed many of the questions of modern chemistry being defined as the study of the composition of waters, movement, growth, embodying, disembodying, drawing the spirits from bodies and bonding the spirits within bodies by the early 4th century Greek-Egyptian What is chemistry Zosimos.
The current model of atomic structure is the quantum mechanical model. This matter can be studied in solid, liquid, or gas statesin isolation or in combination.
The interactionsreactions and transformations that are studied in chemistry are usually the result of interactions between atoms, leading to rearrangements of the chemical bonds which hold atoms together. Such behaviors are studied in a chemistry laboratory. The chemistry laboratory stereotypically uses various forms of laboratory glassware.
Solutions of substances in reagent bottles, including ammonium hydroxide and nitric acidilluminated in different colors A chemical reaction is a transformation of some substances into one or more different substances. It can be symbolically depicted through a chemical equationwhich usually involves atoms as subjects.
The number of atoms on the left and the right in the equation for a chemical transformation is equal. When the number of atoms on either side is unequal, the transformation is referred to as a nuclear reaction or radioactive decay.
The type of chemical reactions a substance may undergo and the energy changes that may accompany it are constrained by certain basic rules, known as chemical laws. Energy and entropy considerations are invariably important in almost all chemical studies. Chemical substances are classified in terms of their structurephase, as well as their chemical compositions.
They can be analyzed using the tools of chemical analysise. Scientists engaged in chemical research are known as chemists.
Several concepts are essential for the study of chemistry; some of them are: Matter In chemistry, matter is defined as anything that has rest mass and volume it takes up space and is made up of particles.
The particles that make up matter have rest mass as well — not all particles have rest mass, such as the photon. Matter can be a pure chemical substance or a mixture of substances.
Atom A diagram of an atom based on the Bohr model The atom is the basic unit of chemistry. It consists of a dense core called the atomic nucleus surrounded by a space occupied by an electron cloud.
The nucleus is made up of positively charged protons and uncharged neutrons together called nucleonswhile the electron cloud consists of negatively charged electrons which orbit the nucleus. In a neutral atom, the negatively charged electrons balance out the positive charge of the protons.
The nucleus is dense; the mass of a nucleon is appromixately 1, times that of an electron, yet the radius of an atom is about 10, times that of its nucleus. Chemical element A chemical element is a pure substance which is composed of a single type of atom, characterized by its particular number of protons in the nuclei of its atoms, known as the atomic number and represented by the symbol Z.
The mass number is the sum of the number of protons and neutrons in a nucleus. Although all the nuclei of all atoms belonging to one element will have the same atomic number, they may not necessarily have the same mass number; atoms of an element which have different mass numbers are known as isotopes.
For example, all atoms with 6 protons in their nuclei are atoms of the chemical element carbonbut atoms of carbon may have mass numbers of 12 or The periodic table is arranged in groupsor columns, and periodsor rows. The periodic table is useful in identifying periodic trends.
Chemical compound A compound is a pure chemical substance composed of more than one element. The properties of a compound bear little similarity to those of its elements.
Organic compounds are named according to the organic nomenclature system. When a compound has more than one component, then they are divided into two classes, the electropositive and the electronegative components. In this scheme each chemical substance is identifiable by a number known as its CAS registry number.
A molecule is the smallest indivisible portion of a pure chemical substance that has its unique set of chemical properties, that is, its potential to undergo a certain set of chemical reactions with other substances. However, this definition only works well for substances that are composed of molecules, which is not true of many substances see below.
Molecules are typically a set of atoms bound together by covalent bondssuch that the structure is electrically neutral and all valence electrons are paired with other electrons either in bonds or in lone pairs.
Thus, molecules exist as electrically neutral units, unlike ions. When this rule is broken, giving the "molecule" a charge, the result is sometimes named a molecular ion or a polyatomic ion.
However, the discrete and separate nature of the molecular concept usually requires that molecular ions be present only in well-separated form, such as a directed beam in a vacuum in a mass spectrometer.
Charged polyatomic collections residing in solids for example, common sulfate or nitrate ions are generally not considered "molecules" in chemistry. Some molecules contain one or more unpaired electrons, creating radicals.
Most radicals are comparatively reactive, but some, such as nitric oxide NO can be stable.Chemistry, like all the natural sciences, begins with the direct observation of nature— in this case, of matter.
But when we look at matter in bulk, we see only the "forest", not the "trees"— the atoms and molecules of which matter is composed— whose properties ultimately determine the nature and behavior of the matter we are looking at.
Chemistry is the study of matter: its composition, properties, and reactivity. This material roughly covers a first-year high school or college course, and a good understanding of algebra is helpful. Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more.
In more formal terms chemistry is the study of matter and the changes it can undergo. Chemists sometimes refer to matter as ‘stuff’, and indeed so it is.
Chemistry is the science of matter.
This may sound simple, but chemistry is a complex and broad topic that broaches a wide variety of fields. From. Chemistry definition is - a science that deals with the composition, structure, and properties of substances and with the transformations that they undergo.
How to use chemistry in a sentence.
a science that deals with the composition, structure, and properties of substances and with the transformations that they undergo. Chemistry is a branch of natural science that deals principally with the properties of substances, the changes they undergo, and the natural laws that describe these changes.