unit 4 Flashcards
biochemistry
oxygen and hydrogen is bonded by–
covalent bonds
what do both oxygen and hydrogen share?
both share some electrons
water is a what type of molecule?
water is a polar molecule
which one is bigger, oxygen atom or hydrogen atom?
oxygen is bigger with 8 protons
O (oxygen) is–
“stronger”, pulls most of the electrons towards it
O becomes a little–
negative
H (hydrogen) is–
“weaker”, loses electrons
H becomes a little–
positive
what does the unevenness of O and H make the water molecule?
the unevenness makes the water molecule polar
how does water stick together?
the positive end of one water molecule attracts the negative end of another water molecule, until all the water molecules are connected
what are these types of water connections called?
hydrogen bonds
what is a hydrogen bond?
a weak attraction between the slightly negative oxygen of one water molecule, and the slightly positive hydrogen of another water molecule
H-bonds are weak alone, but–
strong in high numbers
cohesion–
attraction between molecules of the same substance. water-water
why is water very cohisive?
because of the H-bonds, molecules hold on to each other very tightly and create high surface tension
adhesion–
attraction between molecules of different substances, water loves other substances.
what is an example of adhesion?
meniscus in graduated cylinder: water sticks to the glass and “crawls up”
capillary action–
when water moves up a thin tube by itself, it’s called capillary action. this is how water moves up in plants
how does water move up in plants from the roots to the leaves?
through tubes called xylem (the thinner the tube, the higher the water)
true or false: water can move up through small tubes against gravity
true
true or false: water is able to absorb large amounts of heat, lakes and oceans stabilize land.
true
true or false: water temperatures most substances (good solvent). water inside the cells and body can carry nutrients and waste around.
true
true or false: water absorbs heat when it evaporates, organisms can cool off
true
how does some insects walk and other things float on water?
because water has high surface tension