Unit 3 – Lecture 2. Levels of Organization – review Atom Molecule Biomolecule [aka macro-...
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Transcript of Unit 3 – Lecture 2. Levels of Organization – review Atom Molecule Biomolecule [aka macro-...
Unit 3 – Lecture 2
Levels of Organization – reviewAtomMoleculeBiomolecule
[aka macro-molecule]
Organelle
CellTissueOrganOrgan systemOrganism
MoleculesMolecule – composed of two or more atoms
can be made of a single element or multiple elements
has no overall chargeexample: H2 – two atoms of hydrogen
Molecules – cont’dCompound – a molecule made of two or more
elementsmy abbreviation = cmpd(s)MUST have more than one element presentEx: H2O [2 atoms of hydrogen, 1 atom of
oxygen]ionic compounds have a positive or
negative chargeEx: NH4+
Molecules – cont’dTypes of BondsCovalent Bonds
formed when atoms share valence electrons“co” – together valence electron – electron in the outermost
shell of an atoma strong bondEx: H2O
Molecules – cont’dTypes of BondsIonic Bonds
formed when atoms gain or lose electrons by transfer
weaker than a covalent bondEx: NaCl
Properties of WaterApproximately 2/3 of your body is water…so
apparently it’s quite important…
What makes water so important??
Water is a Polar MoleculePolar Molecule: has no overall charge [hence…
“molecule”] but has a side that is more electronegative
electronegativity – the ability of an atom to attract electrons to itselfuneven distribution of electrons leads to a
negative pull on one side
Water is a Polar MoleculeThe oxygen side of the molecule is much
more electronegative than the hydrogen side
Water is a Polar MoleculeIt is the “Universal Solvent”
water given this term because it is able to dissolve many substancesthis is because of its polarity
solvent: a substance that is used to dissolve a solute.
solute: a substance that is dissolved by the solvent
Ex: water [solvent] dissolves sugar [solute]
Water is a Polar MoleculePolar is aka Hydrophilic
hydrophilic: literally, “water-loving”“hydro” = water“philos / phil / philia” = to lovedissolve easily in water [like sugar]
hydrophobic: literally, “water- fearing”“phobia / phobic / phobos” = to fearaka non-polar do not dissolve or mix easily in water [like
lipids]
Water Performs H-BondingHydrogen Bond: bond formed between a H
and a more electronegative atomis very weakis not a true “bond” but an attractionusually takes place between oxygen [O], nitrogen [N], or fluorine [F]
Water Performs H-BondingAdhesion – the ability of water to form H-bonds
with other molecules [to “stick” to other things ]
think “adhesive”ex: straw in water
water climbs above the surface levelaka capillary action
major way blood flows through the capillaries in your body and through the roots of plants.
Water Performs H-BondingCohesion – the ability of water to form H-bonds
with other water moleculescauses surface tensionEx: water drops form small spheres, can
overfill a glass, some bugs can walk on water
Water Expands when Freezingis less dense when frozen; most substances are more denseallows it to float on water when frozenif ice sunk, lakes & ponds would freeze solid
in winter
Water has a High Specific HeatSpecific Heat – amount of energy it takes for
the temperature of a substance to increase or decrease
makes homeostasis MUCH easier
MixturesMixture – a combination of multiple substances
that…can be physically separatedare not combined chemicallycan be homogenous or heterogenous
Mixtures – cont’dMixtures can be homogenous or heterogeneoushomogenous – appearance and consistency
are the same throughout “genous” – typetypically called solutions
heterogeneous – appearance & consistency are different throughoutEx: …?
Mixtures – cont’dSolution – a mixture that…is homogenousis in a single phase
solid, liquid, or gascan have different phases dissolved in one
anothergas in liquid [carbonated water]solid in solid [alloys – carbon/iron = steel;
copper/zinc = brass]solid in liquid [sugar water]etc.
Mixtures – cont’duses the term “solute” & “solvent”solubility – the ability of a substance to
dissolve in another