BIOL 11000 1st Edition Lecture 4Atoms and Elements - Subatomic particles are allalike - Elements: o Each element is made of one type of atom o Different elements have different atoms o Different atoms have different composition of identical subatomic particles o Elements defined by atomic number= number of protons in the nucleus o For an atom to be electrically neutral, the number of electrons will equal number of protonsSubatomic mass - An atom with one proton (hydrogen) has a mass of 1 o What’s the unit of measure? Atomic mass unit (AMU)- Remember Avogadro’s number? Mole=6.02 x 10^23 o Really a conversion number between AMU and grams o Mole of water= 18ngrams o A mole of protons has a mass of 1 gram o One proton has a mass of 1 gram o One proton has a mass of 1/6.02x10^23 gram or 1.7 x 10^-24 grams Isotopes - Atoms with same number of protons and electrons, different number of neutrons o Same element, same atomic number o Different atomic mass 12C = isotope of carbon with mass of 12 (6P 6N) - Some isotopes are unstable- nuclei spontaneously spit apart and release energy These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Unstable isotopes are radioactive o 14C (6P 8N) is radioactive and unstable - Much easier to detect released energy than atoms themselves so radioactive isotopes are very useful as tracers o Allow us to follow where atoms go and what they become o Bone scan for detecting cancer metastasizing to bone Atoms - Most of an atom is empty space - The elctrons don’t have neat orbits but rather occupy volumes called orbitals o Description of where electrons might be found based on Quantum Mechanics Electron Shells - Electrons are arranged in a structure - 2 levels of structure: o Electron orbitals- more specific, allow 2 electrons/ orbital o Electron shell- more general, a set of orbitals of approximately equal energy make one shell. - Orbitals are ordered by energy, filled from lowest energy to highest lowest filled
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