why do we care abt chemical bonding?
the structure of molecules basically determines their function
metabolism = chemical reactions on reactants done by enzymes
DNA transcription= protein attaches to DNA to start this process
how does the protein/enzyme know which reactant is connect one for it or where to go?
structure of these molecules is the reason for this process
structure comes from bonding of the atoms together
types of chemical bonds:
bonds form bw atoms to form molecules
molecules form bc atoms that make them up are more stable than individuals atoms
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why do we care abt chemical bonding?
the structure of molecules basically determines their function
metabolism = chemical reactions on reactants done by enzymes
DNA transcription= protein attaches to DNA to start this process
how does the protein/enzyme know which reactant is connect one for it or where to go?
structure of these molecules is the reason for this process
structure comes from bonding of the atoms together
types of chemical bonds:
bonds form bw atoms to form molecules
molecules form bc atoms that make them up are more stable than individuals atoms
3 types of chemical bonds:
metal w/non metal: ionic bond
electrons actually transferred from non metal to metal
non metal w/non-metal:covalent bond
sharing of electrons
metal w/ metal
sharing “sea” of electrons
properties of NaCl (sodium chloride):
forms colorless crystal that is cubic and are hard and brittle
high Mp (802 degrees)
conducts electricity when melted (but not in solid- so not metallic or like graphite)
simple ionic compounds:
contain a metal and a non metal (eg. Na (left side metal) Cl (right side non metal))
has one element with low electronegativity (metal)
has one element with high electronegativity(non metal)
metals form cations, configurationnon metals form anions
each ion typically achieves noble gas congfiguration
why? trade off bw energy required to gain or lose electrons and stabilization of the system when ionic bonds are formed
ionic compounds are neutral
sodium chloride:
what color is Na+(cation +)?
purple (smaller one)
cations get small and shrink bc of the imbalance of protons pulling on electrons
each Cl- is surrounded by Na+ ions
each Na+ is surrounded by 6 Cl- ions
cations:
positively charged
smaller than corresponding atom (protons > e-= protons imbalance)
simple cations form when metals lose electrons (ie elements with low electronegativity) (Na 3s1 →3s0 => [NE]
charge usually corresponds to loss of electrons back to “core” but not bc this is more stable loss of electrons always requires energy
why do cations form then? (Na+=Cl- → much more stable)
be highly charged ions form stronger bonds-which are more stable
anions:
negatively charged
larger than corresponding atom
simple anions formed when non metals gain electrons (ie elements w high electronegativity)
charge usually corresponds to gain of electrons to the next filled (sub) shell (ie noble gas configuration)
what charge do u expect on :
K (metal/cation +1) +1
Mg (metal/cation) +2
AL (metal /cation) +3
S (nonmetal/anoin) -2
Br (non-metal/anion) -1
an atom has a valence configuration of S2 P3.what ion will it form in an ionic compound?
-3
* transition metal ions always form a 2+ ion (and often others as well)