Atom

This model was created to account for chemical phenomena such as bonding, rather than physical phenomena such as atomic spectra. The manufacture of these beads requires a large glass furnace and annealing kiln. The cubes could share edges or faces to form chemical bonds. They are made using traditional glassworking techniques from Italy that are more often used to make art glass objects. Lewis in 1916, had cubical atoms with electrons statically held at the corners. Furnace glass are a special type of art bead. Another model of historical interest, proposed by Gilbert N. Magatama are traditional Japanese beads, and cinnabar was often used for beads in China.

Further refinements of quantum theory such as the Dirac equation and quantum field theory made smaller impacts on the theory of atoms. Rudraksha beads are customary in India for making Buddhist and Hindu rosaries (malas). Even today, these theories are used in the Hartree-Fock quantum chemical method to determine the energy levels of atoms. Other ethnic beads include Dzi beads and African brass beads. Together with Wolfgang Pauli's exclusion principle, this allowed study of atoms with great precision when digital computers became available. Other beads considered trade beads are those made in Africa, by and for Africans, such as Kiffa beads. In 1925, Erwin Schroedinger developed a full theory of quantum mechanics, described by the Schroedinger equation. Precious metals and ivory are also imitated.

However, the model was unable to explain multielectron atoms, predict transition rates or describe fine and hyperfine structure. Often beads are made to look like a more expensive original material, especially in the case of fake pearls and simulated rocks, minerals, and gemstones. The ad hoc Bohr-Sommerfeld model was extremely difficult to use, but it made impressive predictions in agreement with certain spectral properties. Styles and colors go in and out of production, so vintage cuts and colors are often prized with a similarly associated price tag. Bohr's model was extended by Arnold Sommerfeld in 1916 to include elliptical orbits, using a quantization of generalized momentum. They are a high-lead crystal, have an incredible sparkle and clarity, and are often multi-faceted to resemble gemstones. They were not allowed to spiral into the nucleus, because they could not lose energy in a continuous manner; they could only make quantum leaps between fixed energy levels. Swarovski crystal beads are also prized by hobbyists.

In 1913, Niels Bohr used this idea in his Bohr model of the atom, in which the electrons could only orbit the nucleus in particular circular orbits with fixed angular momentum and energy. Chevron beads are a specific, historically important type of trade bead. Quantum theory revolutionized physics at the beginning of the 20^th century when Max Planck and Albert Einstein postulated that light energy is emitted or absorbed in fixed amounts known as quanta. Trade beads are various types of beads made in Europe specifically to be used in the slave trade and other trading in Africa. Secondly, the model did not explain why excited atoms emit light only in certain discrete spectra. Pressed glass beads are formed by pressing the hot glass into mold to give the bead its shape. Firstly, a moving electric charge emits electromagnetic waves; according to classical electromagnetism, an orbiting charge would steadily lose energy and spiral towards the nucleus, colliding with it in a tiny fraction of a second. Millefiori beads are made with mutiple canes of glass fused together to make an all-over flower pattern.

The planetary model of the atom still had shortcomings. When the base bead has been formed, other colors of glass can be added to the surface to create many designs. The nucleus was later discovered to contain protons, and further experimentation by Rutherford found that the nuclear mass of most atoms surpassed that of the protons it possessed; this led him to postulate the existence of neutrons, whose existence would be proven in 1932 by James Chadwick. Lampwork beads are made by using a torch to heat a rod of glass and spinning the resulting thread around a metal rod covered in bead release. This led to the planetary model of the atom in which pointlike electrons orbited in the space around a massive compact nucleus like planets orbiting the Sun. The beads are glazed in a red hot oven after being machine faceted. About 1 in 8000 of the alpha particles, however, were heavily deflected (by more than 90 degrees). The pattern of facets is always the same and the resulting bead is somewhat oval in the larger sizes.

Rutherford observed that most of the particles passed straight through the sheet with little deflection (striking a fluorescent screen on the other side). They are popular in jewelry and come in sizes from 4mm to 15 mm. In the gold foil experiment, alpha particles (emitted by polonium) were shot through a sheet of gold. Fire-polished beads are faceted glass beads from the Czech republic. However, an experiment conducted in 1909 by colleagues of Ernest Rutherford demonstrated that atoms have a most of their mass and positive charge concentrated in a nucleus. They are composed of many consecutive layers of colored glass which are then cut to show the resulting chevron pattern. At first, it was believed that the electrons were distributed more or less uniformly in a sea of positive charge (the plum pudding model). Chevron Beads are special glass beads, originally made for the slave trade in Africa by glassmakers in Italy.

Physicists later invented a new term for such indivisible units, "elementary particles", since the word atom had come into its common modern use. Seed beads used by craftspersons should not be confused with Seed Beads™: laboratory-grown beads made of PTFE used to generate seeds of protein crystals. Since cathode rays are emitted from matter, this proved that atoms are made up of subatomic particles and are therefore divisible, and not the indivisible atomos postulated by Democritus. There are also good seed beads from France that are available in historic "old-time" colors and are popular for use in repairing or replicating antiquities. Thomson published his work proving that cathode rays are made of negatively charged particles (electrons). Japanese seed beads are more uniform than the Czech ones and have larger holes for the same size of bead. However, in 1897, J.J. Most of today's good quality seed beeds are made in Japan or the Czech Republic.

For much of this time, atoms were thought to be the smallest possible division of matter. These are called "the most brilliant of all seed beads". This theory was validated experimentally in 1911 by French physicist Jean Perrin. Charlotte cuts are seed beads that have a single facet per bead to add sparkle. In 1905, Albert Einstein theorised that this Brownian motion was caused by the water molecules continuously knocking the grains about, and developed a mathematical theory around it. There are now 3 versions of cylinder beads:. In 1827, biologist Robert Brown observed that pollen grains floating in water constantly jiggled about for no apparent reason. Rows and columns in weaving line up more uniformly, so pattern work comes out more accurate and even.

Atomic theory conflicted with the theory of infinite divisibility, which states that matter can always be divided into smaller parts. Because the ends are flat instead of rounded, work created with cylinder beads has a flat, smooth texture. 4NO + 2O₂ → 4NO₂. Unlike regular rounded seed beads, the cylinder beads are quite uniform in shape and size and have large holes for their size. 4NO + O₂ → 2N₂O₃. During the last decade, a new shape of Japanese seed beads, the cylinder bead, has become increasingly popular. In one combination, these gases formed dinitrogen trioxide (N₂O₃), but when he repeated the combination with double the amount of oxygen (a ratio of 1:2), they instead formed nitrogen dioxide (NO₂). Many of the tubed beads you see hanging in the craft stores are stamped with their name on the bottoms, indicating both a wholesale and retail packaging setup.

The experiment in question involved combining nitrous oxide (NO) with oxygen (O₂). Toho, the other major Japanese supplier, seems to have a more flexible packaging policy. He deduced this after the experimental discovery of the law of multiple proportions — that is, if two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers. To accommodate the average "wholesale" customer, whether it be a bead shop or designer, some larger distributors have made deals to receive their wholesale packages of beads in smaller (50 to 250 gram) pre-packaged sizes. In 1808, John Dalton proposed that an element is composed of atoms of a single, unique type, and that although their shape and structure was immutable, atoms of different elements could combine to form more complex structures (chemical compounds). One major supplier, Miyuki, sells factory packages which contain up to 1 kg of beads, and are almost always repackaged into tubes or other containers for retail sale. None of these ideas, however, were founded in scientific experimentation. Thus, a 250 gram wholesale package would fill 25 tubes -- a bit more than the average beader would need.

Sometime between the 5th century BC and 1st century CE, Buddhist and Jaina philosophers in ancient India also began developing atomic theories (see Indian atomism). Standard Japanese seed beads are usually sold in approximately 10 gram tubes. For instance, the atoms of a liquid were thought to be smooth, allowing them to slide over each other. More expensive beads may be sold in 2.5 or 5 gram units. (See atomism for more details.) The Greeks believed that atoms were all made of the same material but had different shapes and sizes, which determined the physical properties of the material. Most Japanese seed beads are repackaged for retail sale in manageable quantities based on price codes. Democritus and Leucippus, Greek philosophers in the 5th century BC, presented the first theory of atoms. Japanese beads are sold by gram weight, never by the hank, despite some seller claims on eBay.

The seeding of the interstellar medium by heavy elements eventually allowed the formation of terrestrial planets like the Earth. As the steel dies wear eventually, they are replaced. These stars fused heavier elements through stellar nucleosynthesis during their lives and through supernova nucleosynthesis as they died. Manual and automatic machinery is in use in the Czech Republic. After Big Bang nucleosynthesis, no heavier elements could be created until the formation of the first stars. Seed bead machinery uses glass rods softened to a red heat, fed into a steel die stamp that forms the shape of the bead with a reciprocating needle that forms the hole. These photons are still detectable today in the cosmic microwave background. Glass rods made with concentric layers of color or stripes of color can be used to make patterns of color in seed beads.

This allows most of the photons in the universe to travel unimpeded for billions of years. An exterior coating of a metallic film adds a lustre to seed beads called "AB" - Aurora Borealis. Once atoms become neutral, they only absorb photons of a discrete absorption spectrum. Linings of pink or blue are also common. This process is called recombination, during which the first neutral atoms took form. Transparent seed beads benefit from lining the interior hole in silver, gold, copper. It was then cool enough to allow the nuclei to capture electrons. The color of the bead can be transparent or opaque.

Big Bang chronology of the atom continues to approximately 379,000 years after the Big Bang when the cosmic temperature had dropped to just 3,000 K. Examples of true black glass are circulating in jewelry pieces made to comemerate the funeral of Queen Victoria. However, although nuclei (fully-ionized atoms) were created, neutral atoms themselves could not form in the intense heat. The receipe for a true black glass was lost during World War I, and modern black glass held to sunlight is a deep purple. Hydrogen makes up approximately 75% of the atoms in the universe; helium makes up 24%; and all other elements make up just 1%. Formulas for different colors of glass are closely guarded. During this process, nuclei of hydrogen and helium formed abundantly, but almost no elements heavier than lithium. The color glass rods are produced from a larger mass melt of some 10 metric tons.

In models of the Big Bang, Big Bang nucleosynthesis predicts that within one to three minutes of the Big Bang almost all atomic material in the universe was created. The excess glass is recycled to form new rods. This was produced at CERN in the ATHENA and ATRAP experiments using the Antiproton Decelerator. The beads are produced in the Czech Republic using a 10 kilogram rod of color glass. Since antimatter is very difficult to produce and store, only a small amount antihydrogen has ever existed on Earth. A production run of a custom made seed bead is 8 kilograms. Antimatter can also form atoms, composed of positrons, antiprotons, and antineutrons. Purchasing Czech beads by the hank is usually a better value than the repackaged beads by far.

When electrons deep inside large atoms are knocked out (for example by beta radiation), replacement atoms fall deep into the electric potential of the nucleus, producing high-energy x-rays. A hank of size 2 bugles or size 11 seed beads generally weighs between 30 and 40 grams, depending on manufacturing variations, coatings or linings. For example, the hyperfine transitions (including the important 21 cm line) produce low-energy radio waves. Not every 20 inch strand of size 11 beads weighs the same. Not all parts of the atomic spectrum are in visible light part of the electromagnetic spectrum. When Czech beads are repackaged, they are usually sold by the gram, which creates some confusion on how many beads come on a hank. Due to the distinctive spectral lines that each element produces, they are able to tell the chemical composition of distant planets, stars and nebulae. They are very often repackaged into tubes, bags, or other containers for retail sale, in quantities varying from 5 grams to 40 or more grams.

In spectroscopic analysis, scientists can use a spectrometer to study the atoms in stars and other distant objects. Czech seed beads are sold from the factories by the hank. The resulting pattern of gaps is called the absorption spectrum. Some vintage 18/0 hanks have had 10 strands of 8-10 inches (200 to 250 mm) each. If a set of atoms is illuminated by a continuous spectrum, it will only absorb specific wavelengths (energies) of photon that correspond to the differences in its energy levels. For example, Charlotte size 13/0 cut beads are generally on short hanks, containing 12 twelve-inch strands. When these atoms fall back toward the ground state, they will produce an emission spectrum. Different hanks (age, type, size) have had from 8 to 14 strands, and lengths have varied from 8 to 20 inches per strand.

If a set of atoms is heated (such as in an arc lamp), their electrons will move into excited states. Different sizes and types of beads may be sold in hanks which have different numbers and lengths of strands. Since each element has a unique set of energy levels, each creates its own light pattern unique to itself: its own spectral signature. There are usually 12 strands of 20 inches of strung beads in each modern hank of 11/o beads. An electron in a higher-energy orbital may drop to a lower-energy orbital by emitting a photon. A hank is unit bundle of strands of seed beads or bugle beads. An electron may move from a lower-energy orbital to a higher-energy orbital by absorbing a photon with energy equal to the difference between the energies of the two levels. Seed beads are sold either by "hank" or by gram weight.

Normally, an atom is found in its lowest-energy ground state; states with higher energy are called excited states.
. Since each element in the periodic table consists of an atom in a unique configuration with different numbers of protons and electrons, each element can also be uniquely described by the energies of its atomic orbitals and the number of electrons within them. Unfortunately online verdors will typically not explain the correlation between size numbers and aughts and millimeters. Many other types of bonds exist, including:. Size numbers are also used. The formation of a bond causes a strong attraction between two atoms, creating molecules or ionic compounds. The origin of the name is debatable.

This can be achieved one of two ways: an atom can either share electrons with other atoms (a covalent bond), or it can remove electrons from (or donate electrons to) other atoms (an ionic bond). The term "aught" refers to how many beads can fit into a standard unit. Atoms may fill their valence shells by chemical bonding. The most popular seed bead size is 11/0 ("eleven-aught"), but sizes range from 22/0 (believed to be the smallest) to 6/0 or 5/0 (the largest). Fluorine is the most reactive of all elements. Larger seed beads are used in various fiber crafts for embellishment, or crochet with fiber or wire. Also, atoms that need only few electrons (such as the halogens) to fill their valence shells are reactive. They may be used for simple stringing, or as spacers between other beads in jewelry.

Alkali metals are therefore very reactive, with caesium, rubidium, and francium being the most reactive of all metals. Usually rounded in shape, seed beads are most commonly used for loom and off-loom bead weaving. Conversely, atoms with few electrons in their valence shell are more reactive it is. "Seed Bead" is a generic term for any small bead. This means that atoms with full valence shells (the noble gases) are very unreactive. Seed Beads are uniformly shaped, spheroidal beads ranging in size from under a millimetre to several millimetres. Every atom is most stable with a full valence shell. .

Alkali metals contain one electron on their outer shell; alkaline earth metals, two electrons; halogens, seven electrons; and various others. Types of decorative beads include:. Therefore, elements with the same number of valence electrons are grouped together in the columns of the periodic table of the elements. fabric, clay). The number of electrons in an atom's outermost shell (the valence shell) governs its bonding behavior. Beads can be woven together with specialized thread, or adhered to a surface (e.g. Atoms that have either lost or gained electrons are called atomic ions (with either positive(+) or negative charge(−), respectively). Beadwork is the craft of making things with beads.

These ultra-heavy elements are generally highly unstable and decay quickly. Glass, plastic, and stone are probably the most common materials, but beads are also made from bone, horn, ivory, metal, shell, pearl, coral, gemstones, polymer clay, metal clay, resin, synthetic minerals, wood, ceramic, fiber, paper, and the seeds of the Bead tree. Elements not normally found in nature have been artificially created by nuclear bombardment; as of 2006, elements have been created through atomic number 116 (given the temporary name ununhexium). Beads range in size from under a millimeter to over a centimeter in diameter. Several elements that do not occur on Earth have been found to be present in stars. As an alternative to piercing, plastic beads may be Moulded Onto a Thread during manufacturing; these MOT beads are often used for the throw necklaces worn at Mardi Gras. Most of the elements lighter than uranium (Z=92) have stable-enough isotopes to occur naturally on Earth (with the notable exception of technetium Z=43). A bead is a small, decorative object that is pierced for threading or stringing.

Virtually all elements heavier than hydrogen and helium were created through stellar nucleosynthesis and supernova nucleosynthesis. Aiko - an all new, extremely precise bead made by Toho, and introduced in 2005. The elements with atomic number 84 (polonium) and heavier have no stable isotopes and are all radioactive. Treasures (formerly Antiques) made by Toho. Almost all isotopes of each element are radioactive; only a few are stable. Delicas® made by Miyuki. Tritium is an unstable isotope which decays through a process called radioactivity. Trade beads or Slave beads.

The hydrogen isotope which also contains one neutron so is called deuterium or hydrogen-2; the hydrogen isotope with two neutrons is called tritium or hydrogen-3. Seed beads. The simplest atom is the hydrogen isotope protium, which has atomic number 1 and atomic mass number 1; it consists of one proton and one electron. Pressed glass beads. The atomic mass listed for each element in the periodic table is an average of the isotope masses found in nature, weighted by their abundance. Millefiori beads. For example, carbon-14 contains 6 protons and 8 neutrons in each atom, for a total mass number of 14. Lead crystal beads.

When writing the name of an isotope, the element name is followed by the mass number. Lampwork beads. These are called the isotopes of an element. Furnace glass beads. Each has the same atomic number but a different mass number. Fire-polished beads. Each element can have numerous kinds of atoms with the same number of protons and electrons but varying numbers of neutrons. Faux natural beads.

The number of neutrons A−Z in an atom has no effect on which element it is. Ethnic beads. The atomic mass A, atomic mass number, or nucleon number of an element is the total number of protons and neutrons in an atom of that element, so-called because each proton and neutron has a mass of about 1 amu. Dichroic beads. The elements may be sorted according to the periodic table in order of increasing atomic number. Cloisonné beads. All atoms with the same atomic number share a wide variety of physical properties and exhibit the same chemical properties. Chevron beads.

For example, carbon atoms are atoms containing six protons. The atomic number determines which chemical element the atom is. Atoms are generally classified by their atomic number Z, which corresponds to the number of protons in the atom. At room temperature, atoms making up gases in the air move at a speed of 500 m/s (about 1100 mph or 1800 km/h).

As the temperature of the system is increased, the kinetic energy of the particles in the system is increased, and their speed of motion increases. The temperature of a collection of atoms is a measure of the average energy of motion of those atoms; at 0 kelvin (absolute zero) atoms would have no motion. This contracts the size of the electron shells, so that more electrons fit in the only a slightly greater volume. The reason for this is that heavy elements have large positive charge on their nuclei, which strongly attract the electrons to the center of the atom.

Their sizes are roughly the same to within a factor of 2. Atoms of different elements do vary in size, but the sizes do not scale linearly with the mass of the atom. Nearly all the mass of an atom is in its nucleus, yet almost all the space in an atom is filled by its electrons. If an atom were the size of a stadium, the nucleus would be the size of a marble.

So the ratio of the size of the hydrogen atom to its nucleus is about 100,000:1. Compare this to the size of the proton (the only particle in the nucleus of the hydrogen atom), which is approximately 10⁻¹⁵ m. As an example, the size of a hydrogen atom is estimated to be approximately 1.0586×10⁻¹⁰ m (twice the Bohr radius). For any atom, one might use the radius at which the electrons of the valence shell are most likely to be found.

For atoms that can form solid crystal lattices, the distance between the centers of adjacent atoms can be easily determined by x-ray diffraction, giving an estimate of the atoms' size. Since the electron cloud does not have a sharp cutoff, the size of an atom is not easily defined. These include: electron microscopes (such as in scanning tunneling microscopy (STM)), atomic force microscopy (AFM), nuclear magnetic resonance (NMR) and x-ray microscopy. However, there are ways of detecting the positions of atoms on the surface of a solid or a thin film so as to obtain images.

Atoms are much smaller than the wavelengths of light that human vision can detect, so atoms cannot be seen in any kind of optical microscope. In nuclear fission, a single large nucleus is divided into two or more smaller nuclei. In nuclear fusion, two light nuclei come together and merge into a single heavier nucleus. Nuclear transformations also take place in nuclear reactions.

When an excited nucleus emits a photon to return to the ground state, the photon has very high energy and is called a gamma ray. However, these transitions typically require thousands of times more energy than electron excitations. In addition, like the electrons of the atom, the nucleons of nuclei may be pushed into excited states of higher energy. Decays involving electrons or positrons are due to the weak nuclear interaction.

Radioactive transformations proceed by a wide variety of modes, but the most common are alpha decay (emission of a helium nucleus) and beta decay (emission of an electron). When nuclei transformations take place spontaneously, this process is called radioactivity. Nuclei can undergo transformations that affect the number of protons and neutrons they contain, a process called radioactive decay. The nucleons are held together in the nucleus by the strong nuclear force.

The constituent protons and neutrons of the atomic nucleus are collectively called nucleons. Electrons with differing s have very slight energy differences called hyperfine splitting. Orbitals of differing m are degenerate but may be separated by applying a magnetic field, creating the Zeeman effect. In most atoms, orbitals of differing l are not exactly degenerate but separated into a fine structure.

In the illustration, the letters s, p, d and f (corresponding to l = 0, 1, 2, 3) describe the shape of the atomic orbital. Electrons with varying l and m have distinctive shapes denoted by spectroscopic notation. In addition to its principal quantum number n, an electron is distinguished by three other quantum numbers: the azimuthal quantum number l (describing the orbital angular momentum of the electron), the magnetic quantum number m (describing the direction of the angular momentum vector), and the spin quantum number s (describing the direction of the electron's intrinsic angular momentum). An excited atom's electrons will spontaneously fall into lower levels, emitting excess energy as a photons, until it returns to the ground state.

Under some circumstances an electron may be excited to a higher energy level (that is, it absorbs energy from an external source and leaps to a higher shell), leaving a space in a lower shell. In the most stable ground state, an atom's electrons will fill up its shells in order of increasing energy. The occupied shell of greatest n is the valence shell, even if it only has one electron. An electron shell can hold up to 2n² electrons, where n is the principal quantum number of the shell.

Core electrons (those not in the outer shell) play a role, but it is usually in terms of a secondary effect due to screening of the positive charge in the atomic nucleus. The electrons in the outermost shell, called the valence electrons, have the greatest influence on chemical behavior. Generally, the higher the energy level of a shell, the further away it is from the nucleus. These configurations are determined by the quantum mechanics of electrons in the electric potential of the atom; the principal quantum number determines particular electron shells with distinct energy levels.

Electrons of an atom remain within certain, predictable electron configurations. The chemical behavior of atoms is due to interactions between electrons. Protons and neutrons are bound together in the nucleus by gluons carrying the strong nuclear force. Electrons are bound to the nucleus by photons carrying the electromagnetic force.

The subatomic force carrying particles (called gauge bosons) are also important to atoms. Although they do not occur in ordinary matter, two other heavier generations of quarks and leptons may be generated in high-energy collisions. The proton is composed of two up quarks and one down quark, whereas the neutron is composed of one up quark and two down quarks. Ordinary atoms are composed only of quarks and leptons of the first generation.

Together, the electron and neutrino are both leptons. In addition, the electron is known to have a nearly massless neutral partner called a neutrino. However, protons and neutrons themselves are now known to consist of still smaller particles called quarks. Before 1961, the subatomic particles were thought to consist of only protons, neutrons and electrons.

This nucleus is itself made up of nucleons: positively charged protons and chargeless neutrons. The electrons orbit a small, dense body containing all of the positive charge in the atom, called the atomic nucleus. The first of these to be discovered was the negatively charged electron, which is easily ejected from atoms during ionization. Although the name "atom" was applied at a time when atoms were thought to be indivisible, it is now known that the atom can be broken down into a number of smaller components.

. Molecules are made up of multiple atoms; for example, a molecule of water is a combination of two hydrogen atoms and one oxygen atom. Atoms are able to bond into molecules and other types of chemical compounds. Atoms are the fundamental building blocks of chemistry, and are conserved in chemical reactions.

The number of protons and neutrons in the atomic nucleus may also change, via nuclear fusion, nuclear fission or radioactive decay. Atoms which have either a deficit or a surplus of electrons are called ions. Electrons that are furthest from the nucleus may be transferred to other nearby atoms or even shared between atoms. Atoms are electrically neutral if they have an equal number of protons and electrons.

Within a single element, the number of neutrons may also vary, determining the isotope of that element. The number of protons in an atom (called the atomic number) determines the element of the atom. Atoms differ in the number of each of the subatomic particles they contain. The electrons form the much larger electron cloud surrounding the nucleus.

Protons and neutrons are both nucleons and make up the dense, massive atomic nucleus. Most atoms are composed of three types of massive subatomic particles which govern their external properties:. This definition must not be confused with that of chemical atoms, since chemical atoms (hereafter "atoms") are composed of smaller subatomic particles. The word atom may also refer to the smallest possible indivisble fundamental particle.

In chemistry and physics, an atom (Greek άτομον meaning "indivisible") is the smallest possible particle of a chemical element that retains its chemical properties. van der Waals bonds. hydrogen bonds; and. metallic bonds;.

coordinate covalent bonds;. polar covalent bonds;. neutrons, which have no charge and are about 1838 times more massive than electrons. protons, which have a positive charge and are about 1836 times more massive than electrons; and.

electrons, which have a negative charge and are the least massive of the three;.