Atom

This model was created to account for chemical phenomena such as bonding, rather than physical phenomena such as atomic spectra. He is a majority stock holder of a bank in Tulsa, Oklahoma, and regularly attends car shows, charities, and plays the occasional game of golf. The cubes could share edges or faces to form chemical bonds. As of 2005, Sanders lives in suburban Detroit with his wife, Lauren Campbell, a former weekend news anchor in Detroit, and three children. Lewis in 1916, had cubical atoms with electrons statically held at the corners. Only Gale Sayers (34) and Jim Brown (35) were younger. Another model of historical interest, proposed by Gilbert N. On August 8, 2004, Sanders became the third youngest player ever inducted into the Pro Football Hall of Fame.

Further refinements of quantum theory such as the Dirac equation and quantum field theory made smaller impacts on the theory of atoms. On February 15, 2000, arbitrator Sam Kagel ruled that Sanders was in default of his bonus agreement and owed $5.5 million plus interest over the next three years.[2]. Even today, these theories are used in the Hartree-Fock quantum chemical method to determine the energy levels of atoms. When he retired with several years left on his contract, the Lions demanded that he return $7.3 million of the bonus.[1] Sanders refused, and the Lions sued and eventually won a judgment against him. Together with Wolfgang Pauli's exclusion principle, this allowed study of atoms with great precision when digital computers became available. Two years beforehand, Sanders had renewed his contract with the Lions for $35.4 million over 6 years with an $11 million signing bonus. In 1925, Erwin Schroedinger developed a full theory of quantum mechanics, described by the Schroedinger equation. Sanders's retirement was a matter of some controversy.

However, the model was unable to explain multielectron atoms, predict transition rates or describe fine and hyperfine structure. Sanders' propensity for gambling on taking a loss in order to break long runs, a lack of power in short yardage situations and shortcomings as a pass receiver and blocker lead some to believe that others, such as Brown, Payton, Smith or Marshall Faulk, were better overall players. The ad hoc Bohr-Sommerfeld model was extremely difficult to use, but it made impressive predictions in agreement with certain spectral properties. Many people say he is the greatest running back of all time, arguably one of the greatest players in professional football history, but others say he only has himself to blame for his premature retirement. Bohr's model was extended by Arnold Sommerfeld in 1916 to include elliptical orbits, using a quantization of generalized momentum. Sanders place in history is a matter of some debate. 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. Perhaps his most impressive statistical achievement, though, is to join Jim Brown as only players among the NFL's 50 all-time rushing leaders to average 5 yards a carry (only a handful manage above 4.5 yards per carry).

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. Only Payton and Emmitt Smith, who broke the record in 2002 have rushed for more yards than Sanders. 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. He retired within a one-season striking distance of Walter Payton's career rushing mark of 16,726 yards. Secondly, the model did not explain why excited atoms emit light only in certain discrete spectra. He left football healthy and in his prime, having gained 15,269 rushing yards, 2,921 receiving yards, 118 kickoff return yards, and 109 touchdowns (99 rushing and 10 receiving). 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. On July 28, 1999, at the age of 31, Sanders shocked many when he announced his retirement from pro football.

The planetary model of the atom still had shortcomings. As of 2006, the 1991 divisional playoff victory is the only postseason win the Lions have recorded since the 1970 AFL-NFL Merger. 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. Detroit made the playoffs 4 more times during Sanders' career, but each time they were eliminated in the first round. 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. However, they were crushed by the Washington Redskins 41-13 in the NFC championship game, and Sanders was held to just 59 total yards. About 1 in 8000 of the alpha particles, however, were heavily deflected (by more than 90 degrees). Aided by Sanders 1,855 combined rushing/receiving yards and 17 touchdowns during the season, they recorded a 12-4 record and went on to defeat the Dallas Cowboys 38-6 in the divisional playoffs.

Rutherford observed that most of the particles passed straight through the sheet with little deflection (striking a fluorescent screen on the other side). The closest they ever came was in the 1991 season. In the gold foil experiment, alpha particles (emitted by polonium) were shot through a sheet of gold. Despite his individual success, the Lions never reached the Super Bowl while Sanders played for them (or any other time before or after that). 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. He shared the league's Most Valuable Player with Brett Favre. At first, it was believed that the electrons were distributed more or less uniformly in a sea of positive charge (the plum pudding model). He also set an NFL record by rushing for at least 100 yards in 14 consecutive games.

Physicists later invented a new term for such indivisible units, "elementary particles", since the word atom had come into its common modern use. He was the first running back to rush for 1,500 yards in five seasons and the only one to do it four consecutive years. 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. Rushing for 2,053 yards, he became only the third player to reach 2,000 yards in a single season. Thomson published his work proving that cathode rays are made of negatively charged particles (electrons). Sanders' most productive year came in 1997. However, in 1897, J.J. Unlike many of his contemporaries, he would usually finish a touchdown run or catch by simply handing the ball to the nearest official.

For much of this time, atoms were thought to be the smallest possible division of matter. Despite his flashy playing style, Sanders was rarely seen celebrating after the whistle was blown. This theory was validated experimentally in 1911 by French physicist Jean Perrin. Also of note was his on-field humility. 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. This, combined with his low center of gravity allowed remarkably quick starts and stops -- he was notorious for sometimes running the full width of the field to gain only a yard on a play then, on the next, suddenly breaking through a hole for a long gain. In 1827, biologist Robert Brown observed that pollen grains floating in water constantly jiggled about for no apparent reason. Further, Sanders was able to dazzle onlookers at an ESPN slam-dunk contest by jamming comfortably from a flat footed position demonstrating his other defining characteristic -- explosiveness.

Atomic theory conflicted with the theory of infinite divisibility, which states that matter can always be divided into smaller parts. Though short, Sanders was very stocky -- his playing weight of 200 pounds was in fact the same as Walter Payton and only slightly under the NFL average for a back. 4NO + 2O₂ → 4NO₂. Sanders was far too quick for defenders to hit solidly on a consistent basis, and too strong to bring down with arm tackles. 4NO + O₂ → 2N₂O₃. Though again there were concerns about his size it turned out that these concerns were mostly unfounded. 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). The Detroit Lions selected Barry Sanders third overall with their 1st-round pick in the 1989 draft.

The experiment in question involved combining nitrous oxide (NO) with oxygen (O₂). In 2003, Sanders was enshrined in the College Football Hall of Fame. 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. Rather than try to set more records as a senior, Sanders declared himself eligible for the NFL draft and left OSU as the team's all time leading scorer with 330 points (55 touchdowns). 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). His rushing yards and touchdowns in that year still stand (quite easily) as NCAA single season records. None of these ideas, however, were founded in scientific experimentation. "I could study the great approach to the game that [Thomas] had." In his junior year, Sanders went on to lead the nation in rushing yards (2,628), total yards (3,250), touchdowns (39) and scoring (234 points) en route to winning the 1988 Heisman Trophy.

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). He called it a "great experience". For instance, the atoms of a liquid were thought to be smooth, allowing them to slide over each other. Recruited as a kick returner, Sanders spent his first two years at Oklahoma State University as a backup for All-American Running Back Thurman Thomas. (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. Standing at just 5 feet 8 inches, most college coaches thought he was too small. Democritus and Leucippus, Greek philosophers in the 5th century BC, presented the first theory of atoms. In the final seven games of the season, he rushed for 1,322 yards.

The seeding of the interstellar medium by heavy elements eventually allowed the formation of terrestrial planets like the Earth. Barry Sanders' first attempt at running back didn't come until the fourth game of his senior year (1985) at Wichita North High School. These stars fused heavier elements through stellar nucleosynthesis during their lives and through supernova nucleosynthesis as they died. He was born to William and Shirley Ann Sanders in Wichita, Kansas. After Big Bang nucleosynthesis, no heavier elements could be created until the formation of the first stars. . These photons are still detectable today in the cosmic microwave background. Barry David Sanders (born July 16, 1968 in Wichita, Kansas) is a former American football running back in the NFL who spent his entire professional career with the Detroit Lions.

This allows most of the photons in the universe to travel unimpeded for billions of years. C1, C8. Once atoms become neutral, they only absorb photons of a discrete absorption spectrum. Sam Mellinger, "A Hard Man to Catch", The Kansas City Star, August 8, 2004, pp. This process is called recombination, during which the first neutral atoms took form. ISBN 1578601398. It was then cool enough to allow the nuclei to capture electrons. Mark McCormick and Barry Sanders, Barry Sanders: Now you See Him: His Story in His Own Words (Emmis Books, 2003).

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. Craig Ellenport, "Sanders was born to run", NFL.com, August 8, 2004.[4]. However, although nuclei (fully-ionized atoms) were created, neutral atoms themselves could not form in the intense heat. Gil Brandt, "Hall recall: Barry Sanders", NFL.com, July 22, 2004.[3]. Hydrogen makes up approximately 75% of the atoms in the universe; helium makes up 24%; and all other elements make up just 1%. (it should be noted that the number was shared with former running back Billy Sims and Hall of Fame defensive back Lem Barney, who also attended the event). During this process, nuclei of hydrogen and helium formed abundantly, but almost no elements heavier than lithium. On November 25, 2004, his jersey number #20 was retired before the Lions' annual Thanksgiving Day game.

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. On August 8, 2004, he was inducted to the Hall of Fame along with Bob Brown, Carl Eller, and John Elway. This was produced at CERN in the ATHENA and ATRAP experiments using the Antiproton Decelerator. On January 31, 2004, he was elected into the Pro Football Hall of Fame. Since antimatter is very difficult to produce and store, only a small amount antihydrogen has ever existed on Earth. His 18,190 career yards from scrimmage place him fourth on the all-time list. Antimatter can also form atoms, composed of positrons, antiprotons, and antineutrons. At retirement, Sanders' 15,269 career rushing yards placed him second behind Walter Payton's 16,726 yards.

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. Over his professional career, he rushed for at least 100 yards in 76 games, just short of Walter Payton's 77 games and Emmitt Smith's 78 games. For example, the hyperfine transitions (including the important 21 cm line) produce low-energy radio waves. Each of his 10 years from 1989 through 1998 he was first- or second-team All-Pro and selected to the Pro Bowl. Not all parts of the atomic spectrum are in visible light part of the electromagnetic spectrum. He shared the NFL MVP award with Brett Favre. Due to the distinctive spectral lines that each element produces, they are able to tell the chemical composition of distant planets, stars and nebulae. In 1997, he set an NFL record by rushing for at least 100 yards in 14 consecutive games and became only the third player to reach 2,000 yards in a single season.

In spectroscopic analysis, scientists can use a spectrometer to study the atoms in stars and other distant objects. In the 1989 draft, he was selected in the 1st round (3rd overall) by the Detroit Lions. The resulting pattern of gaps is called the absorption spectrum. In 1988, Sanders won the Heisman Trophy while attending Oklahoma State University in Stillwater, Oklahoma. 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. He rushed for over 1,500 yards in a season for an NFL record five times. When these atoms fall back toward the ground state, they will produce an emission spectrum. 1990, 1994, 1996 and 1997.

If a set of atoms is heated (such as in an arc lamp), their electrons will move into excited states. Sanders led the NFL in rushing four times. Since each element has a unique set of energy levels, each creates its own light pattern unique to itself: its own spectral signature. As a receiver, Sanders made 352 receptions for 2,921 yards and 10 touchdowns for the Detroit Lions. An electron in a higher-energy orbital may drop to a lower-energy orbital by emitting a photon. 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.

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. Many other types of bonds exist, including:. The formation of a bond causes a strong attraction between two atoms, creating molecules or ionic compounds.

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). Atoms may fill their valence shells by chemical bonding. Fluorine is the most reactive of all elements. Also, atoms that need only few electrons (such as the halogens) to fill their valence shells are reactive.

Alkali metals are therefore very reactive, with caesium, rubidium, and francium being the most reactive of all metals. Conversely, atoms with few electrons in their valence shell are more reactive it is. This means that atoms with full valence shells (the noble gases) are very unreactive. 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. Therefore, elements with the same number of valence electrons are grouped together in the columns of the periodic table of the elements. The number of electrons in an atom's outermost shell (the valence shell) governs its bonding behavior. Atoms that have either lost or gained electrons are called atomic ions (with either positive(+) or negative charge(−), respectively).

These ultra-heavy elements are generally highly unstable and decay quickly. 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). Several elements that do not occur on Earth have been found to be present in stars. 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).

Virtually all elements heavier than hydrogen and helium were created through stellar nucleosynthesis and supernova nucleosynthesis. The elements with atomic number 84 (polonium) and heavier have no stable isotopes and are all radioactive. Almost all isotopes of each element are radioactive; only a few are stable. Tritium is an unstable isotope which decays through a process called radioactivity.

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. 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. 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. For example, carbon-14 contains 6 protons and 8 neutrons in each atom, for a total mass number of 14.

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

The number of neutrons A−Z in an atom has no effect on which element it is. 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. The elements may be sorted according to the periodic table in order of increasing atomic number. All atoms with the same atomic number share a wide variety of physical properties and exhibit the same chemical properties.

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;.