A model of an atom.
- An atom includes a nucleus, and then a series of orbital circles that surround this nucleus similar to the solar system structure.
- The protons and the neutrons reside in the nucleus.
- The electrons are in the orbitals.
- The amount of protons in the nucleus of an atom determines its atomic number.
The definition of an atom is the smallest component of an element, characterized by a sharing of the chemical properties of the element and a nucleus with neutrons, protons and electrons.
Structure of an Atom
Hydrogen and helium are examples of elements that have an atom.
- Obs. any of the indivisible particles postulated by philosophers as the basic component of all matter
- a tiny particle of anything; jot
- any of the smallest particles of an element that combine with similar particles of other elements to produce compounds: atoms combine to form molecules, and consist of a complex arrangement of electrons revolving about a positively charged nucleus containing (except for hydrogen) protons and neutrons and other particles
Origin of atomMiddle English attome from Old French atome from Classical Latin atomus from Classical Greek atomos, uncut, indivisible, atom from a-, not + tomos from temnein, to cut: see -tomy
- a. A part or particle considered to be an irreducible constituent of a specified system.b. The irreducible, indestructible material unit postulated by ancient atomism.
- An extremely small part, quantity, or amount.
- Physics & Chemistry a. The smallest unit of an element, having all the characteristics of that element and consisting of a very small and dense central nucleus containing protons and neutrons, surrounded by one or more shells of orbiting electrons. Atoms remain undivided in chemical reactions except for the donation, acceptance, or exchange of valence electrons.b. This unit regarded as a source of nuclear energy.
Origin of atomMiddle English attome from Latin atomus from Greek atomos indivisible, atom a- not ; see a- 1. tomos cutting ( from temnein to cut ; see tem- in Indo-European roots.)
- (now historical) The smallest medieval unit of time, equal to fifteen ninety-fourths of a second. [from 10th c.]
- (history of science) A hypothetical particle posited by Greek philosophers as an ultimate and indivisible component of matter. [from 15th c.]
- (physics, chemistry) The smallest possible amount of matter which still retains its identity as a chemical element, now known to consist of a nucleus surrounded by electrons. [from 16th c.]
- A molecule is a close combination of atoms.
- A mote of dust in a sunbeam. [from 16th c.]
- The smallest, indivisible constituent part or unit of something. (Now generally interpreted as a figurative use of the physics sense, above.) [from 17th c.]
- A very small amount (of something immaterial); a whit. [from 17th c.]
- (mathematics) A non-zero member of a Boolean algebra that is not a union of any other elements. [from 20th c.]
- (computing, programming, Lisp) An individual number or symbol, as opposed to a list. A scalar value.
atom - Computer Definition
(1) (Atom) Intel x86 chips. See Intel Atom.
(2) (Atom) A Web feed. See Atom syndication format.
(3) A single element. See atomic.
(4) A fundamental building block of matter. Atoms are microscopic solar systems that are made up of particles and mostly space. Within that space, electrons create an outer shell by circling a nucleus containing protons and neutrons of similar mass. Neutrons have no electrical charge, but protons have a positive charge. Since there are the same number of electrons as there are protons, and since electrons have a negative charge, the atom has a net charge of zero. See electron. Since the days of ancient Greece, the atom was considered "the" smallest element of matter and indivisible, which is what "atomic" means. However, in the 1960s, we discovered that the nucleus was made up of more particles, which were named quarks and leptons. Perhaps some day, we will find those particles made up of even more particles in our never ending quest to discover what we are really made of.