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  • Bohr Diagrams

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    Bohr diagrams of elements from groups 1, 14, 17 and 18, and periods 1, 2 and 3 are shown. Period 1, in which the 1n shell is filling, contains hydrogen and helium. Hydrogen, in group 1, has one valence electron. Helium, in group 18, has two valence electrons. The 1n shell holds a maximum of two electrons, so the shell is full and the electron configuration is stable. Period 2, in which the 2n shell is filling, contains lithium, carbon, fluorine, and neon. Lithium, in group 1, has 1 valence electron. Carbon, in group 14, has 4 valence electrons. Fluorine, in group 17, has 7 valence electrons. Neon, in group 18, has 8 valence electrons, a full octet. Period 3, in which the 3n shell is filling, contains sodium, silicon, chlorine, and argon. Sodium, in group 1, has 1 valence electron. Silicon, in group 14, has 4 valence electrons. Chlorine, in group 17, has 7 valence electrons. Argon, in group 18, has 8 valence electrons, a full octet.

    Figure 2.7 (OpenStax, Biology 2e) caption: Bohr diagrams indicate how many electrons fill each principal shell. Group 18 elements (helium, neon, and argon) have a full outer, or valence, shell. A full valence shell is the most stable electron configuration. Elements in other groups have partially filled valence shells and gain or lose electrons to achieve a stable electron configuration.

    (Source: OpenStax)

  • Bohr Atomic Model

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    Three concentric circles around the nucleus of a hydrogen atom represent principal shells. These are named 1 n, 2 n, and 3 n in order of increasing distance from the nucleus. An electron orbits in the shell closest to the nucleus, 1 n.

    Figure 2.6 (OpenStax, Biology 2e) caption: In 1913, Niels Bohrs developed the Bohr model in which electrons exist within principal shells. An electron normally exists in the lowest energy shell available, which is the one closest to the nucleus. Energy from a photon of light can bump it up to a higher energy shell, but this situation is unstable, and the electron quickly decays back to the ground state. In the process, it releases a photon of light.

    (Source: OpenStax)

  • 107-Bohrium

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    3D model of the atom Bohrium

    Bohrium is a synthetic chemical element with the symbol Bh and atomic number 107. It is named after Danish physicist Niels Bohr. As a synthetic element, it can be created in a laboratory but is not found in nature. All known isotopes of bohrium are extremely radioactive.

    (Source: Library Lyna)

  • Atoms

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    Points of light streaking toward a central point. Caption: Matter is made up of tiny particles called atoms.

    What is an atom? It is the smallest particle of an element, and everything is made up of atoms. They consist of three basic particles: protons, electrons, and neutrons. The scientific community has experienced significant breakthroughs which have contributed to the understanding of atoms. Other topics covered include atomic number, atomic mass, Bohr model, electron cloud, and isotope.

    (Source: DCMP)

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  • Chemistry

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    • Simulation

    A collection of Chemistry related resources

    A collection containing 67 resources, curated by Benetech

  • Elements

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    3D models and images of the entire periodic table of elements

    A collection containing 118 resources, curated by Library Lyna