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Atoms and Molecules 2.1 Elements and Atoms
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Why do we need to study chemistry in a biology class? Elements are _____ Matter is _____ Solid, liquid, gas 92 are natural Six are basic for life CHNOPS Others: Na, K, Ca, Fe, Mg Periodic table
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What are atoms? Smallest part of an _________ Important terms Atomic symbol Atomic mass (not weight) Atomic number Atomic particles include: Electron shell
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What is a mole? Used as a standardizing unit Avogadro’s number 6.023 X 10 23 We’ll play with this later…
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What are isotopes? Different number of ___ Same atomic _________ Different atomic ______ Sometimes radioactive Used as a tracer (e.g. I)
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How are electrons arranged in an atom? Bohr diagrams These show orbitals 1 st energy shell = ___ electrons 2 nd energy shell = ___ electrons 3 rd energy shell = ___ electrons Octet rule Determines bonding behavior Two or more atoms bonded together = _______
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Atoms and Molecules 2.2 Bonds form molecules
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What is a molecule? Two or more _______ sharing electrons Molecules are the smallest form of a _______ Diatomic molecules Several types of bonds Ionic Covalent Polar Non-polar Hydrogen
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What is an ionic bond? One atom ______ an electron Creates ions Bond = attraction between opposite charges
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What is a covalent bond? Two atoms ________ electrons Single Double Triple Two types Non-polar Polar Water is best example
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What are hydrogen bonds? Not a true bond Due to the polar covalent nature of molecule
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Atoms and Molecules 2.3 Properties of water
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What are the properties of water? Polar Universal solvent Cohesion Adhesion High heat capacity High surface tension Solid water is less dense than liquid water
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What is polarity again? Other molecules may be defined as Hydrophobic hydrophilic
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Why is water a good solvent? First some terms Solution = ______ + _____ Water is polar…
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What is the difference between cohesion and adhesion? Cohesion Due to ____ bonding Adhesion
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What is high heat capacity and why is it important? Calorie = amount of heat needed to raise ______ of water by ______. Hydrogen bonds change melting and boiling points Without hydrogen Would melt at -100 degrees C Would boil at -91 degrees C
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What is high surface tension? Due to hydrogen bonds
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Why is it important that liquid water is more dense than solid water?
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Atoms and Molecules 2.4 Acids, bases and pH
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What is pH? = -log[H + ] pH scale How was it created?
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What are acidic solutions? Donate________________
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What are basic solutions? Either take up ____ or release _____
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What is a buffer? Important in our blood!
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