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- Dictionaryatom/ˈatəm/
noun
- 1. the smallest particle of a chemical element that can exist.
- 2. a level of amateur sport, typically involving children aged between nine and eleven: Canadian "eight atom hockey teams"
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Nov 19, 2023 · Learn what an atom is, how it is composed of protons, neutrons, and electrons, and how it forms elements, isotopes, and ions. Explore the history of atomic theory, the properties of atoms, and the misconceptions and facts about them.
- Overview
- Atomic model
An atom is the basic building block of chemistry. It is the smallest unit into which matter can be divided without the release of electrically charged particles. It also is the smallest unit of matter that has the characteristic properties of a chemical element.
Are all atoms the same size?
All atoms are roughly the same size, whether they have 3 or 90 electrons. Approximately 50 million atoms of solid matter lined up in a row would measure 1 cm (0.4 inches). A convenient unit of length for measuring atomic sizes is the angstrom, defined as 10−10 meters.
What does the mass of an atom consist of?
The mass of an atom consists of the mass of the nucleus plus that of the electrons. That means the atomic mass unit is not exactly the same as the mass of the proton or neutron.
How is the atomic number of an atom defined?
Most matter consists of an agglomeration of molecules, which can be separated relatively easily. Molecules, in turn, are composed of atoms joined by chemical bonds that are more difficult to break. Each individual atom consists of smaller particles—namely, electrons and nuclei. These particles are electrically charged, and the electric forces on the charge are responsible for holding the atom together. Attempts to separate these smaller constituent particles require ever-increasing amounts of energy and result in the creation of new subatomic particles, many of which are charged.
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As noted in the introduction to this article, an atom consists largely of empty space. The nucleus is the positively charged centre of an atom and contains most of its mass. It is composed of protons, which have a positive charge, and neutrons, which have no charge. Protons, neutrons, and the electrons surrounding them are long-lived particles present in all ordinary, naturally occurring atoms. Other subatomic particles may be found in association with these three types of particles. They can be created only with the addition of enormous amounts of energy, however, and are very short-lived.
Learn what atoms and molecules are, how they are composed of sub-atomic particles, and how they interact with each other. Explore the history, properties, and examples of atoms and molecules with videos and FAQs.
- 115 min
- As atoms come together to form molecules, chemical bonds bind them together. As a consequence of sharing or exchanging electrons between the atoms,...
- Water is known to be a basic molecule consisting of a few atoms. Basic molecular substances are molecules in which strong covalent bonds bind the a...
- Ozone is a molecule made up of three atoms of oxygen. The chemical ozone symbol is O3 as the oxygen atom symbol is O. Most of the ozone present in...
- An electrically neutral group of two or more atoms held together by chemical bonds is the most basic definition of molecule. In that sense, no, by...
- Atoms are composed of three elementary particles: protons, electrons , and neutrons. The atom’s nucleus (center) contains the protons (positively c...
- Molecules are subject to molecular bonds. Something like table salt ( NaCl) is a compound because it is made of more than one type of element (sodi...
- Many atoms consist of a positively charged nucleus consisting of protons and neutrons surrounded by a cloud of electrons charged negatively. An ato...
- The protons and neutrons are packed together into the center of the atom (which is called the nucleus) and the much smaller electrons, whizzing aro...
- A tiny particle of a chemical element is called an atom, which may or may not exist independently. Molecules refer to the group of atoms that the b...
An atom is the smallest particle of an element that has the same chemical properties as the element. Learn about the history of atomic theory, the structure and behavior of atoms, and the types of atoms and isotopes.
Dec 15, 2021 · An atom is the basic unit of matter that consists of a nucleus of protons and neutrons surrounded by electrons. Learn about the discovery, structure and properties of atoms, as well as their role in the universe and chemistry.
Learn the origin, synonyms, and examples of the word atom, which means the smallest particle of an element or a tiny particle. Find out how atoms are related to energy, matter, and ancient philosophy.
May 5, 2019 · An atom is the basic unit of an element that cannot be broken down by chemical means. Learn about the structure, types, and examples of atoms, and what is not an atom.
