Atoms_molecules - Biology 111, Principles of Biology...

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Biology 111, Principles of Biology Lecture Outlines Atoms & Molecules All matter is composed of ELEMENTS ELEMENT: A substance with specific properties that cannot be broken down or converted into different substances by ordinary chemical means. These are the basic building blocks for all MATTER (see Periodic Table of the Elements). ATOM: Smallest unit of an element ATOM MOLECULE MACROMOLECULE Atoms are composed of sub-atomic particles: Sub-atomic particle Charge Approx. wt. (a.m.u.) proton +1 1 neutron 0 1 electron -1 0 Atomic Structure (see Figure 2.4): NUCLEUS: Dense core Contains protons and neutrons ELECTRON ORBITALS: Amorphous "cloud" surrounding the nucleus Electrostatic forces hold electrons in orbitals Number of electrons per orbital: 1st orbital 2 e- 2nd orbital 8 e- 3rd orbital 8 e- See Figure 2.8: Electrons in orbitals further from the nucleus have higher states of potential energy (see Figure 2.7): Full electron orbitals are stable (chemically inert, non-reactive) Noble Gasses: Full orbitals (last column of Periodic Table) ATOMIC NUMBER = # of protons in nucleus ATOMIC MASS (weight)= # protons + # neutrons "Pure" elements are electrically neutral (# protons = # electrons)
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This note was uploaded on 04/17/2008 for the course BIOL 111 taught by Professor Lux during the Fall '07 term at Lander.

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Atoms_molecules - Biology 111, Principles of Biology...

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