Radiation is a term that describes all the ways energy is emitted by the atom as X rays, gamma rays, neutrons, or charged particles. Most atoms, being stable, are nonradioactive; others are unstable and give off either particles or gamma radiation. Substances bombarded by radioactive particles can become radioactive and yield alpha particles, beta particles, […]
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Aufbau Principle – how an electron enters subshell
Aufbau Principle: An electron enters the subshell that has the least energy. The subshells are filled in the increasing order of energy. The ascending order is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d,…. Order of filling the subshells: 1s < 2s < 2p < […]
Electronic configuration & quantum numbers
Electronic configuration: The distribution of electrons in an atom is known as electronic configuration. Spectroscopic studies, which are used in elucidating electronic configuration show that four numbers known as quantum numbers are required to characterize each electron in an atom. Principal Quantum number (n) Principal Quantum number (n): It represents the main electronic energy shells […]
Atomic Structure – shell model, based on the Bohr model
In this post, various aspects of the shell model of the atomic structure (based on the Bohr model) have been discussed. Electron Orbits There are as many orbiting electrons as there are protons in the nucleus. The radii of the electron orbits are assumed to be quite larger than the size of the nucleus. In […]
Important formulas related to Atomic Structure
In this post, you will find a bunch of important formulas related to atomic structure. formulas related to atomic number & mass number (a) Atomic number (Z) = number of electrons = number of protons (b) Mass number (A) = number of protons + number of neutrons = atomic number + number of neutrons (c) […]
Electron shells for the first 20 elements & shells filling rules
In this post, we will present a diagram displaying the electron shells for the first 20 elements of the Periodic Table.The number of electrons increases by 1 each time. (It is the same as the proton number.) The shells fill according to the rules given in the next section. Electron shells filling rules Electrons are […]
The atoms of the first 20 elements in the periodic table
In the Periodic Table, the elements are arranged in order of increasing proton number. Here is a quick list of the names of the first 20 elements in the periodic table: hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine, argon, potassium, & calcium. In this post, […]
Isotopes – revision notes
Isotopes are atoms of the same element, with different numbers of neutrons. The nuclei of different isotopes of the same element have the same number of protons but different numbers of neutrons. Most elements have isotopes. For example, calcium has six, magnesium has three, hydrogen has three, iron has four, and chlorine has two isotopes. […]
