, lesson 1 | structure of water / hydrogen bonding
ap biology - unit 1
learning g0a Is :
learning objective :
explain how the essential knowledge :
properties of water that result from its the sequence +
subcomponents of biological molecules determit
affect itshe
Polarity and hydrogen bonding their properties
biological function .
living systems rely on water's polarity +
hydrogen bonding
hydrogen bonds lead to cohesion adhesion , and surface tension
,
hydrogen bonding :
oxygen atom is electronegative
8 -
x lone pairs ↓ Oxygen a tom
Y
....
covalent C electrons spend more time w/ oxygens
X bond 2 ↑ electronegative
H Hs + "nog s electrons a
hydrogen partial negative (8) positive (8t) charge
-
forms :
ST ·
8-
hydrogen bonds =
weaker than covalent bonds
H
· 8+
hydrogen bonds are key for water properties
bonds
Pola ui + y hydrogen
: :
two H atoms bonded to an 0 atom water molecules attract each other b/c of
polarity
· bent structure b/c the O atom carries two unshared electrons -
S + end of Hatom W/8 -of O atom
classified as polar molecule b/c of its polar covalent bonds +
bent shape hydrogen bonds >
-
weak interactions between H atom
-
uneven distribution of electrons b/c Oxygen is more electronegative and O atom
solv en + properties :
·
water miecs also attracted to other polar mlecs/ions
solvents dissolve solutes hydrophilice"Water-loving"
-
-
homogenous mixtures of solvents+ solutes are solutions hydrophobic "Water-repelling"
-
-
aqueous solutions + solutions w/ Water as solvent
-
s o l ve n + proper + ies(2) :
· water is an excellent solvent ("universal Solvent") these interactions lead to formation of three-dimensional
some substances don't dissolve well in water sphere of water miecs (hydration shell)
good at dissolving polar miecs ions but bad at nonpolar shells help water particles be
evenly spread out
- -
+
polar-miec that's neutral but has uneven distribution of ex :
hydration shells form around Nacl ions when
charges it's dissolved in Water (Na"surrounded by 0-C1- by Ht)
electrostatic interactions (charge-based attractions) and disperse ions into solution
·
water mless form
positive charges attract negative charges
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