BIOL 200 Chapter Notes - Chapter 2: Unpaired Electron, Covalent Bond, Electron Shell
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BIOL 200 Full Course Notes
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2. 1 atoms, ions, and molecules: the building blocks of chemical evolution. Isotopes: forms of the element with different number of neutrons, therefore have different masses, number of protons remains the same, e. g. 13c vs 12c (6 protons and 7 neutrons vs. 6 protons and 6 neutrons: radioactive isotope (1) nucleus will eventually decay and release radiation (2) neutrons changes into proton (3) e. g. =outermost shell: number of unpaired valence electrons varies among elements (1) carbon is four (2) oxygen is two, atom most stable when valence shell is filled, forming chemical bonds helps these shells be filled. How does covalent bonding hold molecules together: covalent bond, molecules, two atoms share electrons, substances held together by covalent bonds, e. g. H2 is a molecule of two hydrogen atoms: electrons shared equally, nonpolar and polar bonds, electrons in a covalent bond are generally not shared equally among the two atoms, this occurs in compounds .
