Studied by 1 person
condensation reaction
(JOINS)
water formed as a product when two molecules join together.
hydrolysis reaction
(SPLITS)
water reacts with a chemical to break it into smaller molecules.
the three constituents / parts of an atom
proton
neutron
electron
atoms are neutral when…
they have an equal number of protons and electrons.
atoms become charged when….
there is either a deficit or surplus of electrons.
atom
the smallest particle of a chemical element that can exist
element
matter that cannot be decomposed into something simpler
*all atoms of an element have the same number of protons
molecule
atoms that are joined together by a molecular bond
compound
a molecule made up of two or more different atoms
chemical bond
an attraction between atoms/ions/molecules that enables the formation of chemical compounds
ionic bond
involves the transfer of electrons
cation = positive charge
anion = negative charge
covalent bond
involves the sharing of electrons
types of chemical bonds
non-polar covalent bond
polar covalent bond
ionic bond
hydrogen bond
non-polar covalent bond
electrons are shared equally
polar covalent bond
electrons are shared unequally
ionic bond (within a molecule)
attraction between a positively charged ion (cation) and a negatively charged ion (anion)
hydrogen bond (between different molecules)
attraction between 𝛿+ and 𝛿− regions of two different polar molecules
*intermolecular force, not an actual bond
structure of a water molecule
dissolving
when a molecule is separated by another because it is attracted to something
water molecules are polar — where are the electrons polled towards?
the oxygen atom
why do hydrogen bonds form between water molecules?
because the 𝛿+ hydrogen atoms of one water molecule are attracted to the 𝛿− oxygen atom of another water molecule.
what is the maximum number of H-bonds a water molecule can form with other water molecules?
four
cohesion
the ability of water molecules to form hydrogen bonds with each other, causing them to stick together.
cohesion-tension model
*most widely accepted model for movement of water in vascular plants
transpiration (evaporation) occurs because somata are open. as transpiration occurs, it creates negative pressure called tension/suction.
tension created by transpiration ‘pulls’ water in the plant xylem, drawing it upwards.
cohesion pulls up water molecules in a chain as the top-most water is pulled up and out of the somata.
surface tension
a property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of its molecules.
occurs because the outermost layer of molecules are left with fewer molecules to cling to, instead compensating by establishing stronger bonds with neighbours that they do have contact with, creating an inward force.
adhesion
the attraction of water to other polar or charged molecules.
cellulose
a polymer made of glucose units, present in plant cell walls.
*water forms H-bonds with cellulose because of -OH groups in glucose that water sticks too. this allows structures with lots of cellulose to absorb water.
capillary action
the movement of water through a narrow space, often in opposition to external forces (gravity).
helps bring water from the roots
helps soil retain water
capillarity
the rate at which water is pulled upward from the water table into pore spaces (spaces between soil particles) by capillary action.
*the height to which the water rises depends on the type of soil
**different soils have different capillarity rates
solvent
the liquid in which a solute dissolves
solute
the substance that dissolves in a solvent
solution
a mixture of one or more solutes dissolved in a solvent
solvation
the interaction of a solvent with a dissolved solute
*water forms H-bonds with a solute, forming a hydration shell around it.
hydrophilic molecules
molecules that attract water (generally soluble)
*polar, with a charge
hydrophobic molecules
molecules that cannot attract water (insoluble)
*non-polar, without a charge
**hydrophobic molecules attract each other, and will clump together when exposed to water
cytosol
the liquid part of the cytoplasm (a structure common to all cells)
catabolic reactions
break down larger molecules into smaller molecules
anabolic reactions
build larger molecules using smaller molecules
why is water necessary for cellular metabolism?
it dissolves reactants and enzymes, so that they can come together for reactions.
how can water be a medium of transport?
dissolved solutes can be transported in solution around the body of an organism.
