Atom

An atom is the smallest constituent unit of ordinary matter that constitutes a chemical element.

A chemical element is a species of atom having the same number of protons in their atomic nuclei (that is, the same atomic number, or Z).

An atom is the smallest constituent unit of ordinary matter that constitutes a chemical element.

All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic particles, and in everyday as well as scientific usage, "matter" generally includes atoms and anything made up of them, and any particles (or combination of particles) that act as if they have both rest mass and volume.

Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms.

A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or compound molecules made from a variety of atoms (e.g. carbon dioxide).

This is due to quantum effects.

Quantum mechanics, (QM; also known as quantum physics, quantum theory, the wave mechanical model, or matrix mechanics), including quantum field theory, is a fundamental theory in physics which describes nature at the smallest – including atomic and subatomic – scales.

The nucleus is made of one or more protons and a number of neutrons.

Protons and neutrons constitute the nuclei of atoms.

Every atom is composed of a nucleus and one or more electrons bound to the nucleus.

The atomic nucleus is the small, dense region consisting of protons and neutrons at the center of an atom, discovered in 1911 by Ernest Rutherford based on the 1909 Geiger–Marsden gold foil experiment.

These atoms are called ions.

An ion is an atom or molecule that has a net electrical charge.

The nucleus is made of one or more protons and a number of neutrons.

One or more protons are present in the nucleus of every atom; they are a necessary part of the nucleus.

The protons and neutrons in the nucleus are attracted to each other by the nuclear force.

The nuclear force (or nucleon–nucleon interaction or residual strong force) is a force that acts between the protons and neutrons of atoms.

All electrons, nucleons, and nuclei alike are subatomic particles.

In the physical sciences, subatomic particles are particles that are smaller than atoms.

Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals.

A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds.

In this case, the nucleus shatters and leaves behind different elements.

Because any element (or isotope of one) is defined by its number of protons (and neutrons) in its atoms, i.e. in the atomic nucleus, nuclear transmutation occurs in any process where the number of protons or neutrons in the nucleus is changed.

Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals.

A molecule is an electrically neutral group of two or more atoms held together by chemical bonds.

Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals.

A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

Chemistry is the discipline that studies these changes.

Chemistry is the scientific discipline involved with elements and compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.

The number of neutrons defines the isotope of the element.

All isotopes of a given element have the same number of protons but different numbers of neutrons in each atom.

The protons have a positive electric charge whereas the electrons have a negative electric charge.

In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms.

Every atom is composed of a nucleus and one or more electrons bound to the nucleus.

The Coulomb force interaction between the positive protons within atomic nuclei and the negative electrons without, allows the composition of the two known as atoms.

The number of protons in the nucleus, called the atomic number, defines to which chemical element the atom belongs.

The atomic number or proton number (symbol Z) of a chemical element is the number of protons found in the nucleus of every atom of that element.

The word atomos, meaning "uncuttable", was coined by the ancient Greek philosophers Leucippus and his pupil Democritus (c.

BCE) is reported in some ancient sources to have been a philosopher who was the earliest Greek to develop the theory of atomism—the idea that everything is composed entirely of various imperishable, indivisible elements called atoms.

Atoms can attach to one or more other atoms by chemical bonds to form chemical compounds such as molecules or crystals.

A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) composed of atoms from more than one element held together by chemical bonds.

For example, he found that water absorbs carbon dioxide far better than it absorbs nitrogen.

Carbon dioxide consists of a carbon atom covalently double bonded to two oxygen atoms.

The electrons of an atom are attracted to the protons in an atomic nucleus by the electromagnetic force.

The electromagnetic attraction between atomic nuclei and their orbital electrons holds atoms together.

In the fourteenth century, the rediscovery of major works describing atomist teachings, including Lucretius's De rerum natura and Diogenes Laërtius's Lives and Opinions of Eminent Philosophers, led to increased scholarly attention on the subject.

These phenomena are the result of regular, but purposeless motions and interactions of tiny atoms in empty space.

This became known as the plum pudding model.

The plum pudding model is one of several historical scientific models of the atom.