Lecture 2 - Lecture 2: Basic Chemistry Matter: anything...

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Lecture 2: Basic Chemistry Matter: anything that occupies space and has mass. --All matter (gas liquid, solid) composed of elements (substances that can’t be broken down into other substances) --All organisms reduce to chemical elements. Important elements in biology. --92 naturally-occurring elements, 25 essential to life. --C, H, O, and N make up ~96% of the human body, 21 other elements (including trace elements) make up the other 4% -Trace elements: required in very small amounts but you can’t live without them (i.e. iodine, fluoride, etc.) Atoms --Atom- smallest unit that retains the properties of an element Composed of sub-atomic particles ---Proton positive charge ---Neutron neutral ---Electron negative charge Atomic Number - # protons (determines type of element) Mass Number - # protons + # neutrons Isotopes-different forms of the same element -have the same # of protons and electrons but differ in the number of neutrons. -differ in mass and therefore mass # -radioactive isotopes are those where the nucleus decays, emitting particles and energy. Chemistry of atoms The abundant atoms in living systems are all reactive b/c outer shells are not “full” f electrons- tend to form biologically important molecules.
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Lecture 2 - Lecture 2: Basic Chemistry Matter: anything...

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