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  2. VSEPR theory - Wikipedia

    en.wikipedia.org/wiki/VSEPR_theory

    Shows location of unpaired electrons, bonded atoms, and bond angles. The bond angle for water is 104.5°. Valence shell electron pair repulsion ( VSEPR ) theory ( / ˈ v ɛ s p ər , v ə ˈ s ɛ p ər / VESP -ər , [ 1 ] : 410 və- SEP -ər [ 2 ] ) is a model used in chemistry to predict the geometry of individual molecules from the number of ...

  3. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    A compound's empirical formula is a very simple type of chemical formula. [27] It is the simplest integer ratio of the chemical elements that constitute it. [28] For example, water is always composed of a 2:1 ratio of hydrogen to oxygen atoms, and ethanol (ethyl alcohol) is

  4. Bredt's rule - Wikipedia

    en.wikipedia.org/wiki/Bredt's_rule

    In organic chemistry, an anti-Bredt molecule is a bridged molecule with a double bond at the bridgehead. Bredt's rule is the empirical observation that such molecules only form in large ring systems. For example, two of the following norbornene isomers violate Bredt's rule, and are too unstable to prepare: Bridgehead atoms violating Bredt's ...

  5. PhET Interactive Simulations - Wikipedia

    en.wikipedia.org/wiki/PhET_Interactive_Simulations

    PhET Interactive Simulations is part of the University of Colorado Boulder which is a member of the Association of American Universities. [10] The team changes over time and has about 16 members consisting of professors, post-doctoral students, researchers, education specialists, software engineers (sometimes contractors), educators, and administrative assistants. [11]

  6. Ball-and-stick model - Wikipedia

    en.wikipedia.org/wiki/Ball-and-stick_model

    In chemistry, the ball-and-stick model is a molecular model of a chemical substance which displays both the three-dimensional position of the atoms and the bonds between them. [1] The atoms are typically represented by spheres , connected by rods which represent the bonds.

  7. Space-filling model - Wikipedia

    en.wikipedia.org/wiki/Space-filling_model

    A space-filling model of n-octane, the straight chain (normal) hydrocarbon composed of 8 carbons and 18 hydrogens, formulae: CH 3 CH 2 (CH 2) 4 CH 2 CH 3 or C 8 H 18.Note, the representative shown is of a single conformational "pose" of a population of molecules, which, because of low Gibbs energy barriers to rotation about its carbon-carbon bonds (giving the carbon "chain" great flexibility ...

  8. Atomic, molecular, and optical physics - Wikipedia

    en.wikipedia.org/wiki/Atomic,_molecular,_and...

    Molecular physics, while closely related to atomic physics, also overlaps greatly with theoretical chemistry, physical chemistry and chemical physics. [4] Both subfields are primarily concerned with electronic structure and the dynamical processes by which these arrangements change. Generally this work involves using quantum mechanics.

  9. Chemical element - Wikipedia

    en.wikipedia.org/wiki/Chemical_element

    In chemistry, a pure element means a substance whose atoms all (or in practice almost all) have the same atomic number, or number of protons. Nuclear scientists, however, define a pure element as one that consists of only one isotope. [18] For example, a copper wire is 99.99% chemically pure if 99.99% of its atoms are copper, with 29 protons each.