properties of water Flashcards
carbon (C)
forms basic structure of most biomolecules
hydrogen (H)
water - also involved in acid/base reactions
oxygen (O)
water - also breathing
nitrogen (N)
DNA, proteins
what elements make up 96% of all living matter?
C, H, O, N
sulfur (S)
amino acids
phosphorus (P)
call membranes
calcium (Ca)
nerves and muscles
potassium (K)
nerves and muscles
what elements make up 4% of all living matter?
S, P, Ca, K
electron transfer/ionic bonding
- attraction between oppositely charged atoms or ions is an ionic bond.
- ionic bonds can form between any two oppositely charged ions, even if they have not been formed by transfer of an electron from one to the other
importance of water
- approx. 70% of our planet
- most life first developed in water
- first terrestrial organisms took their watery environment with them
- significant amount of water in our bodies
EVERYTHING IS WATER BASED
ionic bonds
no sharing - electron is removed
covalent bonds
molecules share their electrons
two types: polar and non-polar
non-polar covalent
two molecules of same element
polar covalent
electrons not shared evenly
water molecules have polar bonds
- o2 is more electronegative (hogs electrons)
- h2o is asymmetrical
what are the bonds between water molecules?
hydrogen bonds
are hydrogen weak or strong bonds?
weak bonds - this is why h20 is fluid: bonds are broken and remade all the time
essentially: strong enough to hold together, weak enough that you don’t need a special reaction to break it
what are the properties of water?
- water’s cohesion
- water moderates temperature
- ice is less dense than water
- water is the “solvent of life” - pH
water’s cohesion
- many organisms depend on cohesion of H2O (ex: lake bugs that walk on water due to surface tension)
- bonds are broken and remade quickly. at any given time, most H2O molecules are bound
- this creates surface tension
water transport in plants
- think of why straws work or how plants drink. it is because wen you must pull water up, you are pulling up one molecule. because of the hydrogen bonds between molecules, all the other molecules get pulled up as well, which allows us to drink.
water moderates temperature
temperature is due to speed of molecules. faster the speed, higher the heat.
two sub things:
- specific heat
- evaporative cooling
definition of specific heat capacity
amount of heat needed to be absorbed or lost for 1g of substance to change its temp by 1 degree C
specific heat (water and temperature)
- H2O has high specific heat
- when water is heated, some of the heat is used to break H bonds, meaning the temperature doesn’t rise very fast
- when water is cooled, H bonds are formed which gives off heat, making it warmer for longer
- basically, it resists well to temperature changes which allows us to regulate temperature (in our bodies, oceans, etc.)
why is temperature stable along the coastline?
because oceans absorb lots of heat during the day and gives off heat at night, which stabilizes the temperature of the ocean. this is why you don’t get crazy weather swings in cities like vancouver.
evaporative cooling (water & temperature)
- as water is heated, molecules become excited
- most excited ones are at the surface and have absorbed the most energy. they escape into the air (evaporate) taking their heat energy with them, leaving the cooler molecules behind.
- this is how we regulate our body temperature: sweating
ice is less dense than water
- when water freezes, all H bonds are completed forming ice crystals and heat is released
- ice is less dense than water, meaning it floats
- the ice also acts as insulator for water below: this allows for the survival of aquatic organisms
“solvent of life” - water and pH
- everything in our body is regulated to work at pH 7 (pH of pure water)
- homeostasis is used to regulate acid-base balance
- acid rain is an example of how changes in pH can cause disaster in environment ( coral reefs, leafy trees, inhibits aquatic communication)
- changes in pH are bad in biology
solute
substance to be dissolved
solvent
substance used to dissolve solute
aqueous solution
solution where water is the solvent
solution with more OH
basic
solution with more H
acidic
solution where OH = H
neutral
biomolecules basics (organic chem)
- all organic molecules contain C
- C can form 4 covalent bonds
- C commonly forms chains by bonding with itself
- C chains attach together in different configurations
- forms the backbone of most organic molecules
macromolecules/polymers
- made of different units
- long strings of similar/identical molecules covalently bonded together
- monomer is one unit
- chemical methods used to make/break polymers are always the same
explain polymers and eating food
basically, when we eat/digest food, we are breaking apart polymers into their monomers. the monomers are then stored (think buckets) and are used for different functions by the body.
how to you build a polymer?
dehydration reaction - remove/loose an H2O molecule
how do you break down a polymer?
hydrolisis - adding a water molecule back in to break a bond
you always need water to break a bond. what else do some polymers require?
there are usually special enzymes that are required as well to break certain bonds
what are the 4 main classes of biomolecules?
- carbohydrates
- lipids
- proteins
- nucleic acids
