2.2 Water Flashcards
draw a water molecule
…
water structure
water molecules are polar and H bonds form between them; water is made up from two H atoms covalently bonded to an O atom
why are H atoms covalently bonded to an O atom
because of unequal sharing of electrons, because nucleus of O atom is more attractive to electrons than nuclei of the H atom, so electrons are orbiting closer to the O atom
charge of atoms in a water molecule
H atoms have a partial positive charge and O has partial negative charge
why is this an ionic bond
positive and negative ions attract each other to form ionic bond
hydrogen bond
the force that forms when a H atom in 1 polar molecule is attracted to a slightly negative atom of another polar covalent molecule
unequal electron distribution results in …
permanent dipole
draw water polarity in water molecule
…
properties of water
intermolecular bonding between H20 molecules give water distinctive properties; cohesive, adhesive, thermal and solvent properties, transport
cohesion
the tendency of H20 molecules to stick to each other due to the hydrogen bonding between them
why do we have high surface tension in H20
cohesive strenght because of large number of H bonds in H20 cause high surface tension of H20 (the stickiness, due to H bonding of H20 molecules makes h20 surface behave as strong elastic membrane, allowing small organisms or objects denser than H20 to float
surface tension is also responsible for
also responsible for H2O droplets adopting spherical shape, minimizing SA:Vol ratio
adhension
interaction that H2O molecules have with different molecules and explains why H2O molecules stick to other polar compounds by forming H bonds
role of cohesion of water molecule
interaction between H2O molecules
role of adhension of water molecule
interaction between H2O and surrounding material or surface
thermal properties
the H bonds that hold H2O molecules
together are responsible for thermal properties of H2O including high specific heat capacity
specific heat
the amount the amount of heat that must be absorbed or released for 1g of a substance to change T by 1C
why is water a good coolant
because of the large amount of energy needed to turn liquid H2O into vapor H2O
water has a high latent heath of vaporisation
the amount of heath 1g of liquid absorbs to change state to gaseous
how does water cool down a body
when H2O in sweat evaporates on the surface of skin, it cools down its surface by taking away energy n the form of heat
high boiling point
the highest T that water can reach in a liquid state 100C
solvent properties
water is universal solvent - it can dissolve ionic compounds as well as polar compounds (glucose)
water soluble materials
glucose, amino acids, NaCl
not dissolved in H2O
fat soluble, water insoluble substances
how do solvent properties work
occurs because the polar attraction of large quantities of water molecules can sufficiently weaken electrostatic forces and result in the dissociation of atoms
all polar molecules and ions
freely associate and readily dissolve in H2O - hydrohilic
non-polar molecules, fats and oils
don’t freely in H2O - hydrophobic
transport
within blood, depends on solubility of materials
water soluble substances
-NaCl (ions) and C6H12O6 (polar) - freely transported in the blood
-amino acids are transported in an ionized state (amine/carboxyl group charged)
-oxygen is soluble in low amounts - generally transported in eritrocites
water insoluble substances
lipids (cholesterol, fat) are packed with proteins (lipoproteins) for transport
other properties of water
transparency, less dense
transparency
allowing light to pass through it (important for photosynthesis to occur in aquatic plants)
less dense as a solid (ice) than as a liquid
adopts lattice formation (due to H bonds) so more space exists between H2O molecules so the ice is lighter than water (floats) and floating ice insulates bodies of H2O from freezing air when T is bigger than 0C
benefits in living organisms of cohesive properties
1) allow water to be pulled up from the roots to the leaves of plants
2) permit insets, such as pond skaters, to walk/ float on the surface of water to catch their prey
benefits in living organisms of adhesive properties
1) capillary action generated by adhesive forces assists the pumping action of the heart to help blood move though blood vessels
2) adhesion of water molecules to the cell wall of xylem vessels helps water move against gravity from the roots to the leaves
benefits in living organisms of thermal properties
1) evaporation of sweat from body surfaces involves heat loss, which brings about a cooling effect
2) the high specific heat capacity of water makes aquatic ecosystems more stable than terrestrial
benefits in living organisms of solvent properties
1) water dissolves mineral ions in the soil and transports it along xylem vessels from the roots to all parts of the plant
2) water in blood plasma dissolves a range of solutes and gases, which makes it possible for blood to transport nutrients and gases around the body
3) waters versatility makes it an universal solvent and medium for numerous biochemical reactions
versatility
ability of water to exist as a liquid, solid and vapour
transport of glucose
as a polar molecule, glucose is soluble in water so it can be transported in blood. Blood glucose concentration needs to be strictly maintained between certain levels because of its effect on osmotic potential (homeostasis)
transport of amino acids
both - and + charged, soluble in water; solubility varies depending on their size and their R group.
With hydrophilic R group - easily dissolved in H2O and transported in blood
With hydrophobic R group - not easily dissolved in H2O and transported in lower concentration in blood
transport of fats
nonpolar, generally insoluble in H2O, therefore transported in structures called lipoproteins
lipoproteins
a single layer of phospholipids with proteins embedded among the molecules surrounding fat
transport of cholesterol
required for synthesis of many biologically important molecules and is in membranes; requires help of transport lipoproteins to be transported in blood because its’ hydrophobic
transport of oxygen
nonpolar, but so small that it’s soluble to a limited extent - tied to a protein hemoglobin to be transported in blood
transport of sodium chloride
ionic compound, transported in the form of Na+ and Cl- ions - easily dissolved
plasma contains
water, gases, vitamins and trace elements, organic molecules, ions
gases contain
carbon dioxide and oxygen
organic molecules contain
amino acids, nitrogenous waste, proteins, glucose, lipids
proteins contain
fibrinogen, globulin, albumin
