Atomic structure

• Democritus' Atomic Model


  Introduced the concept of indivisible, tiny particles called atoms, solid, indestructible, and indivisible
• Dalton's Atomic Model


  Proposed that atoms are indivisible and indestructible, made up of subatomic particles: protons, neutrons, and electrons, Law of Multiple Proportions: elements are composed of atoms, ratio of elements in a compound is a ratio of the whole numbers
• Thomson's Atomic Model


  Positively charged protons at the center, surrounded by negatively charged electrons in the periphery, Cathode rays are streams of negatively charged particles
• Bohr's Atomic Model


  Introduced energy levels or orbitals, Electrons jump to higher energy levels by absorbing energy, jump to lower energy levels by emitting energy, Quantization of energy levels
• Rutherford's Atomic Model


  Proposed the nuclear model of the atom, Nucleus at the center, surrounded by electron clouds, Protons and neutrons in the nucleus
• Dalton's Model vs Democritus' Model


  Dalton's Model: proposes subatomic particles, understands atoms as composed of protons, neutrons, and electrons, chemical affinity, Law of Multiple Proportions. Democritus' Model: indivisible, solid, and indestructible atoms, no internal structure, no interactions between particles, no laws of combination
• Atoms


  The smallest units of an element that retain the properties of that element, made up of protons, neutrons, and electrons
• Isotopes


  Atoms of the same element, same atomic number, different number of neutrons, same chemical properties, different physical properties
• Ions


  Atoms or groups of atoms that have gained or lost electrons, gained net positive or negative charge, Cations (lost electrons), Anions (gained electrons)
• Atomic Number


  Determined by the number of protons present in the nucleus, unique identifier for each element, determines chemical properties and position in the periodic table
• Isotopes


  Same atomic number (Z), different number of neutrons (N), differing atomic mass, stability, physical and chemical properties
• Radioactive Decay


  Unstable nuclei lose energy, stabilize by releasing radiation, 3 types: Alpha, Beta, Gamma decay, Half-Life: time for half of a sample to decay
• Half-Life


  Time for half of a sample of radioactive material to decay, constant property, exponential decay, decay rate: dN/dt = -λN, related to decay constant λ and ln(2) / t½
• Electron Characteristics


  Electrons are negatively charged particles that orbit the nucleus of an atom, have a small mass, and play a crucial role in chemical reactions.
• Proton Characteristics


  Protons are positively charged particles that make up the nucleus of an atom, have a large mass, and determine the atomic number of an element.
• Electron Spin


  Electron spin is a quantum property measured in units of ħ, and plays a critical role in determining the chemical properties of atoms and molecules.
• Proton Characteristics


  Protons are positively charged particles that reside in the nucleus of an atom, have a large mass, and determine the atomic number of an element.
• Nuclear Interactions


  Protons interact with each other and with neutrons through the strong nuclear force, with electrons through the electromagnetic force, and with each other through the hypermomentum interaction.
• Applications of Protons


  Protons are used in nuclear fission reactions to release energy, in nuclear fusion reactions to form heavier nuclei, and in cancer treatment to deliver high doses of radiation to tumors.
• Proton-Proton Chain Reaction


  The proton-proton chain reaction is a series of nuclear reactions that occur in the core of stars, leading to the formation of heavier elements such as helium and heavier nuclei.
• Protons in Space


  Protons are abundant in space, and are used to study the composition and properties of stars, galaxies, and other cosmic objects in astrophysics and cosmology.
• Electron Configuration


  An electron configuration is a depiction of the arrangement of electrons in an atom, using a notation system that shows the number of electrons in each energy level or shell. The example above shows the electron configuration of a neon atom.
• Energy Levels


  Energy levels refer to the different states of an atom, with the ground state being the lowest energy state and excited states being higher energy states. Shells are energy levels in which electrons occupy specific regions around the nucleus.
• Shells and Subshells


  Shells are energy levels or shells in which electrons occupy specific regions around the nucleus, while subshells are smaller regions within each shell, defined by the energy and spin of the electrons.
• Orbitals


  Orbitals are regions around the nucleus in which electrons are most likely to be found. S-orbitals have zero angular momentum, P-orbitals have one unit of angular momentum, and D-orbitals have two units of angular momentum.
• Spin and Magnetic Moment


  Spin is a fundamental property of particles, including electrons, which determines their intrinsic angular momentum. The magnetic moment of an electron arises from its spin.
• Protons


  Protons are positively charged particles that reside in the nucleus of an atom, and their number determines the element.
• Neutrons


  Neutrons are particles that reside in the nucleus of an atom and have no charge, and their number can vary, resulting in different isotopes of the same element.
• Electrons


  Electrons are negatively charged particles that reside outside the nucleus of an atom, and their number can vary, resulting in different ions of the same element.
• Isotopes


  Isotopes are atoms of the same element that have different numbers of neutrons, which changes their mass but not their chemical properties.
• Ions


  Ions are atoms that have gained or lost electrons, resulting in a change to their charge, and this change affects their chemical behavior.
• Nuclear Region


  The nuclear region is composed of protons and neutrons, which reside in the center of the atom.
• Electron Region


  The electron region is composed of electrons, which orbit around the nucleus of the atom.
• Energy Levels


  Energy levels refer to the different states of an atom, with the ground state being the lowest energy state and excited states being higher energy states.
• Orbitals


  Orbitals are regions around the nucleus in which electrons are most likely to be found, and they are characterized by their angular momentum and energy.
• Electron Spin and Orientation


  Electron spin and orientation refer to the spin of an electron and its orientation with respect to a magnetic field, which can be spin-up or spin-down.
• Strong Nuclear Force


  The strong nuclear force is one of the four fundamental forces of nature, responsible for holding quarks together within protons and neutrons, and holding protons and neutrons together within the nucleus.
• Short-Range Force


  The strong nuclear force is a short-range force that acts only over very small distances, typically on the order of 10^-15 meters. This means it only acts when protons and neutrons are closely together, which is crucial for holding the nucleus together.
• Attractive and Repulsive Components


  The strong nuclear force has both attractive and repulsive components. The attractive force holds quarks together within protons and neutrons, while the repulsive force pushes protons away from each other.
• Stability of the Nucleus


  The stability of the nucleus relies on the balance between the attractive and repulsive components of the strong nuclear force. If the attractive forces are too weak, the nucleus would not hold together, and if the repulsive forces are too strong, the nucleus would break apart.