On food and cooking the science and lore of the kitchen ( PDFDrive ) 1528

roughly similar affinities for electrons, they
willsharethemratherthangainorlosethem
entirely. In order for sharing to occur, the
electron clouds of two atoms must overlap,
and this condition results in a fixed
arrangement in space between two particular
atoms, which thus form a stable combined
structure. The bonding geometry determines
the overall shape of the molecule, and
molecular shape in turn defines the ways in
whichonemoleculecanreactwithothers.
Theelementsmostimportanttolifeon
earth—hydrogen,oxygen,carbon,nitrogen,
phosphorus,sulfur—alltendtoform
covalentbonds,andthesemakepossiblethe
complex,stableassemblagesthatconstitute
ourbodiesandourfoods.Themostfamiliar
purechemicalcompoundsinthekitchenare
water,acovalentcombinationoftwo
hydrogenatomsandanoxygen;andsucrose,
ortablesugar,acombinationofcarbon,
oxygen,andhydrogenatoms.Covalentbonds


aregenerallystrongandstableatroom
temperature:thatis,they’renotbrokenin
significantnumbersunlesssubjectedtoheat
ortoreactivechemicals,includingenzymes.
Unlikesalt,whichdissolvesintoelectrically
chargedions,covalentlybondedmolecules
thatcandissolveinwatergenerallydosoas

intact,electricallyneutralmolecules.
Weak Bonds Between Polar Molecules:
WaterAthirdkindofchemicalbond,abouta
tenthasstrongandstableascovalentbonds,is
thehydrogenbond.Thehydrogenbondisone
of several “weak” bonds that do not form
molecules, but do make temporary links
between different molecules, or between
different parts of one large molecule. Weak
bonds come about because most covalent
bonds leave at least a slight electrical
imbalance among the participating atoms.
Consider water, whose chemical formula is
H2O. The oxygen atom has a greater hunger