Neutron proton model. Thousands of new, high-quality pictures added every day.
Neutron proton model. Until 1932, the atom was known to consist of a positively charged nucleus surrounded by enough negatively charged electrons to make the atom electrically neutral. In this model, it is assumed that the protons and neutrons are considered to be moving in well-defined closed shells. Explore a diagram of an atom with labels to understand its structure and components. Oct 19, 2024 · Researchers have developed a groundbreaking model that merges traditional nuclear physics, focusing on protons and neutrons, with quark-gluon dynamics observed in high energies. The nucleus was thought to contain both protons Sep 1, 2014 · The role of neutron–proton pairing correlations on the structure of nuclei along the N=Zline is reviewed. Their protons, neutrons, and electrons balance. The inset shows beta decay of a free neutron as it is understood today; an electron and antineutrino are created in this process. The discovery of the electron and the proton was crucial to the development of the modern model of the atom and provides an excellent case study in the application of the scientific method. Sep 7, 2023 · For a comparison with the advanced proton-negative pion model of neutron and atomic nucleus based on the identification of the negative pion as a partner of proton in the formation of neutron and The ground states of 12B (5 protons, 7 neutrons) and 12N (7 protons, 5 neutrons) are related to each other and to the 15. electrons C. g. Protons and neutrons form the atomic nucleus. The neutron is a neutrally charged subatomic particle that is about the same mass as the proton. This allows us to identify simultaneously the roles played by other configurations such as the normal pairing term. The neutron was discovered by James Chadwick in 1932, leading to the discovery of nuclear fission in 1938, the first self-sustaining nuclear reactor (Chicago Pile-1, 1942) and the first nuclear weapon (Trinity, 1945). The eigenvalues of the potential are given by the sum of the harmonic potential in 3D (as seen in recitation) and the square well: E N = ℏ ω (N + 3 2) V 0 Jun 21, 2025 · The Nuclear Model of the Atom The nuclear version of the atom originated after Rutherford’s discovery. The nucleus consists of protons and neutrons, each of which has a mass of 1. Rutherford's atomic model became known as the nuclear model. Nov 21, 2020 · Protons and neutrons fill different levels. ” Jul 16, 2020 · Learn about the Bohr model of the atom. Predict how addition or A model of the atomic nucleus showing it as a compact bundle of the two types of nucleons: protons (red) and neutrons (blue). Then, sketch the first electron shell around the nucleus. proton neutron e- electron Complete the sentence. Discovery of Neutrons Find Proton Electron Neutron stock images in HD and millions of other royalty-free stock photos, illustrations and vectors in the Shutterstock collection. May 29, 2024 · Learn about the nuclear shell model, which explains the organization and behavior of protons and neutrons in atomic nuclei using quantum mechanics principles. 1 Magic Numbers The binding energies predicted by the Liquid Drop Model underestimate the actual binding energies of “magic nuclei” for which either the number of neutrons N = (A − Z) or the number of protons, Z is equal to one of the following “magic numbers” In the Rutherford model for the nucleus, a red sphere was a proton with positive charge, and a blue sphere was a proton tightly bound to an electron, with no net charge. This model is the simplest and the most successful of the so called independent particle models of the nucleus. The proton is a baryon and is considered to be composed of two up quarks and one down quark. Surrounding this nucleus are three electron shells, containing a total of 12 electrons. Atom featuring a nucleus of protons and neutrons, surrounded by 3 rings with electron attached to each ring. Test different combinations to produce ions and unstable elements. The protons and neutrons make up the nucleus of the atom, which is surrounded by the electrons belonging to the atom. Its mass is slightly less than the mass of a neutron and approximately 1836 times the mass of an electron (the proton-to-electron mass ratio). Feb 27, 2025 · The carbon Bohr model showcases a nucleus with 6 protons and 6 neutrons. May 10, 2020 · For example, it is the weak force that transforms a neutron into a proton during beta decay. 67 × 10 27 kilograms. The nuclear shell model explains the existence of "magic numbers". This shell can hold a maximum of Studying the proton and neutron structure in 3D: an intricate and dynamic system of quarks and gluons. The enhancement in the Gamow-Teller (GT) transition strength in 70Br compared to the decay of the β lighter 62Ge was suggested as an indication for increased neutron-proton (np) pairing correlation. May 5, 2019 · Nuclear reactions can alter atoms. It has color for each part of the atom, but the atom model also comes with a black and white version. Protons and neutrons, each with a mass of approximately one dalton, are jointly referred to as nucleons (particles present in Nov 19, 2009 · PROTONS The Proton is composed of two up quarks and one down quark (as you can see from the tiny rings of color near the center of each quark. electrons, positrons and neutrinos, because in collision experiments they are always found at the end of the decomposition line. Particular emphasis is placed on the competition between isovector (T=1) and isoscalar (T=0)pair fields. If we assume that the proton, in a certain respect, is a charged neutron, then its mass must differ from the neutron mass due to the charge’s contribution into the total mass-energy. Sep 15, 2025 · The Bohr model of helium depicts a central nucleus composed of 2 protons and 2 neutrons. Protons and neutrons constitute the bulk of the mass of atoms. Thousands of new, high-quality pictures added every day. The three parts of the atom are protons (positively charged), neutrons (neutral charge), and electrons (negatively charged). Protons and neutrons are roughly the same mass as one another (neutrons are slightly more massive). The mass of a neutron is slightly more than of a proton. Sep 2, 2020 · The interactions of the weak force also play an important role in nuclear fusion, where two protons combine. The quantum mechanical nature of these particles appears via the Pauli exclusion principle, which May 14, 2022 · Since the proton is smaller than the neutron by exactly one electron when compared in terms of building blocks alone, we simply subtract one electron from the number we get for the neutron. Most atoms are stable. To find the atomic mass, add the number of protons and neutrons. Phenomenologically at least, the ordering of shell model levels is given by which The notion that the neutron and the proton might be two different states of the same particle (the nucleon) came from the near equality of the n-p, n-n, and p-p nuclear forces (once Coulomb effects were subtracted) Within the quark model, we can think of this symmetry as being a symmetry between the u and d quarks: p = d u u I3 (u) = 1⁄2 May 20, 2024 · Below are two atomic models. Each atom has a nucleus that contains protons and neutrons and has a positive electrical charge. The existence of the neutron's magnetic moment and the large value for the proton magnetic moment indicate that nucleons are not elementary particles. Electrons have a negative electrical charge. From light to heavy nuclei, the proton and neutron Shell Model of Nucleus Aug 9, 2024 · The simplest of the single particle models is the nuclear shell model. It also shows that the number of electrons is the same as the number of protons. In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics. Surrounding this nucleus are four electron shells, accommodating a total of 31 electrons. It is based on the observation that the nuclear mass formula, which describes the nuclear masses quite well on average, fails for certain “magic numbers”, i. As the Mar 17, 2023 · We compute the proton-neutron entanglement entropy in the interacting nuclear shell model for a variety of nuclides and interactions. The proton, along with the neutron which would be discovered a decade later, are considered nucleons that reside in the nucleus of the atom. Sep 7, 2025 · Atom - Nuclear Shell, Structure, Model: Many models describe the way protons and neutrons are arranged inside a nucleus. Video: How to use the PhET build an atom simulation Nov 21, 2023 · James Chadwick's contribution to the atomic model was his discovery of the neutron. But neutrons point in the opposite direction from protons, and less agressively. The third column shows the masses of the three subatomic particles in "atomic The Fermi gas model The Fermi gas model assumes that protons and neutrons are moving freely within the nuclear volume. Proton—positive; electron—negative; neutron—no charge. According to our hypothesize protons and neutrons including quarks are ultimately made of stable elementary particles, i. e. The enhancement in the Gamow-Teller (GT) transition strength in 7 0 B r compared to the β decay of the lighter 6 2 G e was suggested as an indication for increased neutron-proton (𝑛 𝑝) pairing correlation. Build an atom out of protons, neutrons, and electrons, and see how the element, charge, and mass change. Commence by sketching the nucleus, and then illustrate the three electron shells. Nuclear magic numbers occur for neutron or proton number of 2, 8, 20, 28, 50, 82, and 126, as indicated in the figure below. To find neutrons, subtract the number of protons from the atomic mass. 2 MeV protons at similar temperatures (∼300 °C) and similar doses (∼2. It is split into the following layers: 1s/2s, 2p, 3d, 3p, 3s, 4s, nucleus, and cam/lights. Nuclei with magic neutron number N = 2, 8, 20, 28, 50, 82, 126 or magic proton number Z = 2, 8, 20, 28, 50, 82 have a larger binding energy per nucleon than neighboring nuclei, and when N and Z are both magic the binding energy per nucleon is especially large. Most of the atom was empty space, with its mass concentrated in a tiny nucleus. Then play a game to test your ideas! Sample Learning Goals Use the number of protons, neutrons, and electrons to draw a model of the atom, identify the element, and determine the mass and charge. [5] It describes the nucleus as a semiclassical fluid made up of neutrons and protons, with an internal repulsive electrostatic force proportional to the number of protons. The new structural model of the proton is presented in Figure 1 (a). Mar 1, 2012 · The recently proposed spin-aligned neutron–proton pair coupling scheme is studied within a non-orthogonal basis in term of the multistep shell model. 0 dpa). Neutrons are found, together with a similar KEY TAKEAWAYS Key Points An atom is composed of two regions: the nucleus, which is in the center of the atom and contains protons and neutrons, and the outer region of the atom, which holds its electrons in orbit around the nucleus. Shell Model of Nucleus Sep 7, 2025 · Atom - Proton, Neutron, Nucleus: The constitution of the nucleus was poorly understood at the time because the only known particles were the electron and the proton. Surrounding the nucleus are electron shells arranged in circular paths. Samples from the same model alloy were irradiated using fission-neutrons, 2 MeV Fe+ ions or 1. This is a tiny, dense region at the center of the atom. This new approach, which involves enhanced parton distribution functions, has for the first time provided a unified des What are neutrons? Neutron definition: So what is a neutron? A neutron is a undeniably a neutrally charged subatomic particle, found in the nucleus of all atoms except hydrogen. Jan 3, 2018 · Firstly, in that the proton, neutron and electron are three fundamental subatomic particles, there are also other basic subatomic particles. Learn how these subatomic particles define elements' properties and behaviors Explore the structure of an atom with a detailed diagram, highlighting its main parts: nucleus, protons, neutrons, and electrons. Nuclei where the number of protons or neutrons is magic are more tightly bound and often more abundant. The figure below is a common way to A proton is a stable subatomic particle, symbol p, H +, or 1 H + with a positive electric charge of +1 e (elementary charge). 5. On the one hand they are distinct fermions and on the other they evolve in a slightly different average potential because of the residual electromagnetic interaction. Each has a nucleon in the third energy level shown in Fig. The atomic number of an element describes the total number of protons in its nucleus. The liquid drop model is one of the first models of nuclear structure, proposed by Carl Friedrich von Weizsäcker in 1935. The electrons move in a cloud-like region around the nucleus. Explore the structure of an atom, including protons, neutrons, and electrons. In the nuclear atom, the protons and neutrons, which comprise nearly all of the mass of the atom, are located in the nucleus at the center of the atom. To draw the hydrogen Bohr model, start by drawing the nucleus with 1 proton and 0 neutrons at the center. Some results make intuitive sense, for example, that the shell structure, as governed by single-particle and monopole energies, strongly affects the energetically available space and thus the entanglement entropy. PROTON Science > The Atom and Atomic Structure Electron Proton Neutron Isotopes Current models of atomic structure hold that an atom consists of a small, hard nucleus (diameter of about 10 -12 cm) surrounded by a cloud of electrons (10 -8 cm). The neutron lifetime may also provide insight into what happened just moments after the Big Bang. In this model the protons and neutrons occupy separate systems of shells, analogous to the shells in which electrons are found outside the nucleus. These models arise from the need to approximate the interactions within the nucleus, as the strong nuclear force that binds nucleons is intricate and Explore atomic structure and isotopes by building atoms with protons, neutrons, and electrons in this interactive simulation. Together with neutrons, they make up virtually all of the mass of an atom. Jun 2, 2004 · The krypton model has 48 neutrons and 36 protons in the nucleus and 36 electrons. The proton has a positive charge, the electron has a negative charge and the neutron is neutral. The same number of protons and electrons exactly cancel one another in a neutral atom. 1 MeV state in 12 C. The number of Mar 4, 2022 · The proton well is thus slightly shallower and wider than the neutron well because of the Coulomb repulsion. Because opposite electric charges attract one another, negative electrons are attracted to the positive nucleus. Sep 15, 2025 · The model emphasizes the arrangement of these components, showcasing that hydrogen, being the simplest element, has a single proton and electron, with no neutrons in its nucleus. Protons A proton is one of three main particles that make up the atom. Protons and neutrons have approximately the same mass, about 1. The Standard Model also says there are two types of matter particles. As a result of Rutherford’s work, it became clear that an α particle contains two protons and neutrons, and is therefore the nucleus of a helium atom. The boron and nitrogen beta decay emit an e - and e + respectively. In the few seconds after protons and neutrons formed but before they joined together into elements, there was a precise bit of timing. In 1935 Chadwick was appointed to a chair in physics at the University of Liverpool. Positron emission and electron capture —forms of radioactive decay in which a proton becomes a neutron—are not proton decay, since the proton interacts with other particles within the atom. It had been established that nuclei are typically about twice as heavy as can be accounted for by protons alone. [4] Distinct shell gaps are shown at labeled magic numbers, and at . Each model represents a different atom. This model also shows that some electrons can be close to the nucleus and others are further away. The charge on the proton and electron are exactly the same size but opposite. Note: The picture shows a simple model of the carbon atom. One of the most successful and simple to understand is the shell model. Then play a game to test your ideas! The proton well is thus slightly shallower and wider than the neutron well because of the Coulomb repulsion. May 1, 2020 · Transmission electron microscopy (TEM) was used to compare the microstructural defects produced in an Fe9Cr model alloy during exposure to neutrons, protons, or self-ions. Protons carry a positive charge, while neutrons are neutral. This potential model has limitations but it does predict the lower magic numbers. Protons and neutrons clump together to form a central nucleus. The current explanation of the proton is that it is composed of particles known as quarks. Protons have a positive electrical charge of one (+ 1) and a mass of 1 atomic mass unit (amu), which is about 1. Surrounding this nucleus are two electron shells, containing a total of 6 electrons. Electrons are attracted to the protons in the nucleus, but are moving so quickly they fall toward it (orbit) rather than stick to protons. Along with protons and electrons, it is one of the three basic particles making up atoms, the basic building blocks of The model proposed by James Chadwick focuses on the modeling of the atomic nucleus constituted not only by protons (positive charges), but also by neutrons (neutral charges). To explore the 𝑛 𝑝 correlations in nuclei, we systematically The neutron's magnetic moment is exploited to probe the atomic structure of materials using scattering methods and to manipulate the properties of neutron beams in particle accelerators. [PDG 1] It undergoes β− decay (a type of radioactive decay) by turning into a proton while emitting an electron and an electron antineutrino. In fact it depends a bit on how one models the nuclear potential. NOTE: The number protons and electrons is equal to the atomic number. Feb 17, 2010 · An atom consists of three main parts: protons, neutrons, and electrons. In the Standard Model of particle physics Build an atom from scratch, using protons, neutrons, and electrons. See the main points of the model, how to calculate absorbed or emitted energy, and why the model is important. The regions between the large gaps in nucleon energy are referred to as “shells”. But bracketing the existence of these other particles for a moment, what is interesting about the humble proton, neutron and electron is how they interact with one another. In this work, we propose a new model of the structure of protons and neutrons, which answers some other open questions too, such as the taste vibration of neutrinos, the life time of neutrons, and the inter-pretation of complex quark states [8-15]. The magic numbers of nuclei, as well as other properties, can be arrived at by approximating the model with a three-dimensional harmonic oscillator plus a spin–orbit interaction. Describe the location of the proton, electron, and neutron inside the atomic model. The two atoms represented above contain the same number of: A. Understanding the arrangement and behavior of protons, neutrons, and electrons is crucial for comprehending the properties of elements, chemical bonding, and the periodic trends observed in the periodic table. A neutron is a type of hadron that consists of one up quark, and two down quarks. Atoms are made of fundamental particles called protons, neutrons, and electrons. 67x10 -27 kg, roughly 1,800 times the mass of the electron. Each Models of the atomic nucleus are theoretical frameworks designed to understand the complex structure of the nucleus, which houses protons and neutrons and contains almost all of an atom's mass, despite occupying only a fraction of its volume. An example of other known particles include alpha and beta particles. The model is applied to four-, six- and eight-hole N = Z nuclei below the core 100 Sn. protons B. The ground states of 12 B (5 protons, 7 neutrons) and 12 N (7 protons, 5 neutrons) are related to each other and to the 15. The first two shells should contain 2 and 8 electrons The neutron–proton ratio was set by Standard Model physics before the nucleosynthesis era, essentially within the first 1-second after the Big Bang. Elasser, in 1933. This reaction can occur because the mass of the neutron is slightly greater than that of the proton (see neutron decay). The empirical proton and neutron shell gaps are numerically obtained from observed binding energies. The boron and nitrogen beta decay emit an e- and e+ When adding neutrons or protons to a nucleus, the lowest energy state will (generally) consist of filling each orbital as you go upward. They are distinguishable fermions (s = 1⁄2) filling two separate potential wells obeying the Pauli principle (↑↓-pair). Neutrons have no electrical charge. Most of an atom's mass is in the nucleus—… Unlike protons and neutrons, which are located inside the nucleus at the center of the atom, electrons are found outside the nucleus. Numerous scientific findings, including the stability of atoms and the discrete nature of atomic spectra Jan 6, 2024 · Atoms consist of three subatomic particles: protons, neutrons, and electrons. To draw the gallium Bohr model, represent the 31 protons, 39 neutrons, and 31 electrons. A consistent theory was impossible until English physicist James Chadwick discovered the neutron in 1932. The electrons Aug 14, 2024 · In the gallium Bohr model, the nucleus is composed of 31 protons and 39 neutrons. E. Begin by sketching the nucleus, and then draw the four electron shells. It illustrates some basic information like the number of protons and neutrons in the nucleus. This model was first suggested by W. It is believed that under the immense pressures of collapsing massive stars going supernova, the electrons and protons can combine to form neutrons via electron capture, releasing a huge amount of neutrinos. Table 2 6 1 gives the properties and locations of electrons, protons, and neutrons. Oct 25, 2022 · We compute the proton-neutron entanglement entropy in the interacting nuclear shell model for a variety of nuclides and interactions. Jul 30, 2024 · Note: The picture shows a simple model of the carbon atom. We study the recently measured decay of 70Kr into 70Br within the framework of the large-scale shell model. The complex structure of the neutron can also be seen from its mass value as compared to the proton mass. As previously discussed, there is a connection between the number of protons in an element, the atomic number that distinguishes one element from another, and the number of electrons it has. Protons are found in the nucleus of the atom. Since helium has only 2 electrons, both are located in the first shell, known as the K shell. 6-2, each has the quantum number 1+, 1, and each decays to the ground state of carbon. Neutrons can react with positrons or electron neutrinos to create protons and other products in one of the following reactions: At times much earlier than 1 sec, these reactions were fast and maintained the n/p ratio close to 1:1. Mar 11, 2025 · In the magnesium Bohr model, the nucleus consists of 12 protons and 12 neutrons. The aforementioned idea declares that protons and neutrons build up the atom’s robust, positively charged nucleus, and that electrons orbit it at different energy levels, or shells. [1] [2] [3] These subatomic particles are tightly packed at the center of the atom, forming its dense core. Atomic nucleus A model of an atomic nucleus showing it as a compact bundle of protons (red) and neutrons (blue), the two types of nucleons. The first three shells should contain 2, 8, and 18 electrons A neutron in free state is an unstable particle, with a half-life around ten minutes. The structure of the atom is a fundamental concept in Chemistry HL under the International Baccalaureate (IB) curriculum. Some results make intuitive sense, for example that the shell structure, as governed by single-particle and monopole energies, strongly affects the energetically available space and thus the entanglement entropy. , for neutron number N = 20, 28, 50, 82, 126 and proton number Z = 20, 28, 50, 82, as shown previously. neutrons Oct 16, 2025 · That discovery provided a new tool for inducing atomic disintegration, since neutrons, being electrically uncharged, could penetrate undeflected into the atomic nucleus and led to a new model of the atomic nucleus being composed of protons and neutrons. To explore the np correlations in nuclei, we systematically examined the β-decay Along with neutrons, protons make up the nucleus, held together by the strong force. In this ChemTalk tutorial, you will learn how to easily calculate and find the number or protons, neutrons, and electrons in an atom or element Topics Atoms Atomic Structure Isotope Symbols Atomic Nuclei Description Build an atom out of protons, neutrons, and electrons, and see how the element, charge, and mass change. In a nucleus which occupies a certain energy level (for At that time, some people though protons, neutrons, and electrons were lumped together in the atom. Oct 14, 2025 · Neutron, neutral subatomic particle that, in conjunction with protons, makes up the nucleus of every atom except ordinary hydrogen (whose nucleus has one proton and no neutrons). 67 × 10 -24 grams, which scientists define as one atomic mass unit (amu) or one Dalton. He found Electron Shells Niels Bohr proposed an early model of the atom as a central nucleus containing protons and neutrons being orbited by electrons in shells. Each has a nucleon in the third energy level, each has the quantum number 1 +, 1, and each decays to the ground state of carbon. Nevertheless, the proton and neutron have almost identical masses, differing by less than two tenths of a percent! This experiment was the first to report a nuclear reaction, given by the equation: 14N + α → 17O + p [Where α is an alpha particle which contains two protons and two neutrons, and ‘p’ is a proton] The hydrogen nucleus was later named ‘proton’ and recognized as one of the building blocks of the atomic nucleus. Protons have a positive electrical charge. Other particles exist as well, such as alpha and beta particles. The neutron is a subatomic particle, symbol n or n0 , that has no electric charge, and a mass slightly greater than that of a proton. The nucleus is the tiny, dense, central core of the atom and is composed of protons and neutrons. 1 MeV state in 12C. A typical atom consists of three subatomic particles: protons, neutrons, and electrons. The nucleus of the neon atom Ne has ten protons and neutrons, but in its structure of the nucleus model it has both globules separated by an alpha particle (the nucleus of the helium atom), which connects two globules with equally oriented magnetic moments of protons (Fig. Between 8 and 20 neutrons (or protons) is the “sd-shell”, between 28 and 40 neutrons (or protons) is the “fp Jul 29, 2022 · Because protons and neutrons are so much more massive than electrons, almost all of the mass of any atom comes from the nucleus, which contains all of the neutrons and protons. Where = eћ/ 2Mp, is the nuclear magneton which is analogous to the Bohr magneton in atoms but with the electron mass replaced by the proton mass, Mp being the proton mass, ?? and ?? are the gyromagnetic ratios for the proton and the neutron. May 29, 2024 · Both protons and neutrons have a “magnetic moment,” meaning that in a magnetic field, they will point like compasses. ) The overall charge of the proton is positive and so The atom’s nucleus is composed of a combination of protons and neutrons, which are bound together by a strong, nuclear force. This suggests a shell structure, similar to the shell structure in The neutron, however, was not discovered until 1932, when James Chadwick (1891–1974, a student of Rutherford; Nobel Prize in Physics, 1935) discovered it. What elements exist is governed by nuclear physics and we can get a good idea from a simple shell model. The expected properties of these systems, in terms of pairing collective motion, are assessed by different theoretical frameworks including schematic models, realistic Shell Model and . This force of attraction keeps electrons constantly moving through the otherwise empty space around the nucleus. This view of the atom was called the "pudding model" of the atom. To draw the magnesium Bohr model, represent the 12 protons, 12 neutrons, and 12 electrons. Learning Objectives Know the basics of the experiments involving the discoveries of the three subatomic particles Memorize relative charge values and amu masses of the three subatomic particles. Nov 20, 2008 · Standard model gets right answer for proton, neutron masses Correct calculation strengthens theory of quark-gluon interactions in nuclear particles Mar 12, 2025 · We study the recently measured β decay of 7 0 K r into 7 0 B r within the framework of the large-scale shell model. M. This model suggests that nucleons (protons and neutrons) within a nucleus occupy discrete energy levels or “shells. Therefore, protons will not decay into other particles on their own, because they are the lightest (and therefore least energetic) baryon. This article delves into the nuclear atom model, exploring the What is Atomic Chemistry? An atom is the smallest unit of ordinary matter that forms a chemical element. Oct 10, 2024 · The nuclear shell model is a theoretical framework that explains the structure and behaviour of atomic nuclei in terms of energy levels, much like the electron shell model in atomic physics. 12), which do not allow the formation of diatomic neon molecules similar A neutron star is a giant atomic nucleus about 11 km in diameter made especially of neutrons. Learn about protons, neutrons, electrons, and more. Learn their functions and interactions. The story begins in 1932, with the discovery of the neutron by Sir James Chadwick, an English physicist. There is no obvious mnemonic device. fh4da sxsb 4qrkv lmno 5f ep39c u2eik qwar bbbc68 8vkbj