EOSC 114 Lecture 2: EOSC114 – Fragile Systems Part 2
20 Sep 2018
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Document Summary
Elements and atoms: elements are the building blocks of our world. In modern physics, these particles can be further subdivided: nucleus: the center of an atom. Isotopes: different versions of an element that have the same number of protons, but different numbers of neutrons (same atomic number but different atomic mass numbers) Molecules and ions: atoms can be combined to make molecules (compounds). The subscript in a chemical formula indicates number of atoms in a molecule. Normally, molecules have a neutral charge overall: some molecules are held together by ionic bonds, where valences sum to zero. Ions (also known as radicals) are tightly bonded groups of atoms that act as single units in molecules, but which are not complete molecules themselves because they carry a nonzero charge (sum of valences of all atoms). The net charge is indicated with the superscript. Phases of matter: solids (not very fluid or compressible, liquids (fluid but not very compressible, gases (fluid and compressible)
