unit 4 science Flashcards
chemical bond
forces that hold atoms together
result of an electrostatic force
when do atoms create bonds?
when they reach maximum attraction
(when attractive force balances repulsive)
does bonding make atoms more or less stable?
more
octet rule
there must be 8 valence electrons in an atom to have a full ring / most stable (happy)
what are exceptions to the octet rule?
hydrogen / helium - happy with 2
beryllium - happy with 4
boron - happy with 6
ionic bond
when a positive charged atom (cation) and a negatively charged atom (anion) bond
when one atom donates valence electron(s) to make another happy –> they both become happy
will metals loose or gain electrons to become positive?
loose
use + sign for loosing
will loose all valence electrons
will nonmetals gain or loose electrons to become negative?
gain
use - sign for gaining
will gain until 8 valence electrons
ionic compound
needs to have a neutral charge
always write the cations / metals / positive charged elements first
covalent bond
SHARING between two nonmetals
single/double/triple bonds
single bond = 2 electrons
double bond = 4 electrons
triple bond = 6 electrons
nonpolar covalant bond
electrons shared equally
electronegativity sum is between 0 and .4
polar covalant bond
electrons shared unequally
one atom has a stronger pull
electronegativity is between .41 and 1.7
electronegativity
determines type of bonding between atoms
ranges from .7 to 4.0
higher means it wants more / more pull
metallic bonds
attraction between two metals
metal nuclei are attracted to delocalized electrons
