Unit 2 Flashcards
electronegativity
how badly an atom wants to “hog” electrons
electronegativity trends
increases right and decreases down
what is the least and most electronegative elements
least- Fr
most-F
which column on the periodic table has no electronegativity?
the noble gas family (very last one on the right)
which column on the periodic table has the most electronegativity?
the halogen family (the one to the left of the noble gas)
why does electronegativity decrease when you go down?
when u go down the atoms get larger and further away from their nucleus so its easier for their electrons to be stolen
nonpolar covalent has what kind of electronegativity difference
zero
polar covalent has what kind of electronegativity difference
low
ionic bond has what kind of electronegativity difference
high
electron affinity
how much they “want” electrons
electron affinity trends
increases to the right (they want to form octet) and decreases down (they get weaker the lower u go)
cations attract electrons?
smaller
more positive force
attracts fewer electrons
anion attract electrons?
bigger
less positive force
more electron repulsions (distance between nucleus and electrons)
attracts more electrons
ionization energy
energy required to remove an electron
(gas phase)
ionization energy trends
increases right
decreases down
elements of the same family=
similar properties bc have same number of valence electrons
ionic bonds
-mental-nonmetal
-give electrons
covalent bonds
-nonmetal-nonmetal
-share electrons
2 types of covalent bonds
POLAR
-unequal sharing (bent)
NONPOLAR
-equal sharing
How are alloys formed
solution of metal and metal
metalic bonds
metal-metal
good conductors
mixture called an alloy
electronegativity difference between nonpolar and polar
nonpolar = <0.5
polar = 0.5-1.7
electronegativity difference between ionic
> 1.7
another name for ionic bond
coulombic or electrostatic attraction
properties of ionic substances
-form crystals (lattice of positive and negative ions)
-high melting and boiling points
-hard, brittle
-conduct electricity when dissolved or molten
-good insulators as solid
what are metallic attractions due to
due to multiple metallic cations being attracted to delocalized sea of valence electrons
properties of metallic substances
-shiny (luster)
-malleable and ductile
-conduct heat and electricity
-metallic oxides are basic and ionic
-lose electrons to form cations
properties of covalent molecules
-non-lustrous, various colors
-brittle, hard, or soft
-poor conductors
-nonmetallic oxides are acidic and covalent
-form anions by gaining electrons
what does “diapole” mean?
one side of the compound is more negative or more positive on one side
covalent bonds occur at the ___ energy state
lowest
bc if theyre too close together the nuclei will repel each other and if too far apart the attraction will not be enough to hold them together
bond energy
the energy required when breaking a bond or the energy released when bond is formed.
larger atomic radii increase the bond length. Larger bond length decrease the ____?
bond energy
lattice energy
the energy to separate ions from ionic compounds
lattice energy formula
k(Q1Q2)/r
Ionic solids
-consist of cations and aions
-nonvolatile and have high melting points
-do not conduct electricity
-when melted or dissolved the ions can move freely (which causes electricical conduction)
-soluble in polar
-insoluble in non-polar
when ionic radius decreases the attraction___?
increases
two types of alloys
interstitial and substitutional
interstitial alloy
the atoms added to the metal are small and fit in between the metal atoms in the existing holes (interstices)
Substitutional alloy
the atoms added to the metal have similar radii so they replace the atoms in the lattice
third period with lewis structures
able to expand their octet ONLY if theyre the central element
Formal charge formula
how many electrons its supposed to have- what it has
after you find formal charge what do u do
pick the one that has the highest number (ex:-1) on the most electronegative element
dont forget when u have double, triple whatever bonds to…
draw resonance structures!!
Valence shell electron-pair repulsion (VSEPR)
predicts the geometries of molecules and polyatomic ions (3D stucture)
Linear
2
180 degrees
sp
Trigonal planar
3
120 degrees
sp^2
Tetrahedral
4
109.5 degrees
sp^3
overlapping orbitals from a single bonds are known as
sigma bonds
(very strong bonds)
double and triple bonds are formed from unhybridized p orbital are called
pi bonds
triple bond contains
one sigma and two pi bonds
the presence of pi bonds means
the bonds are unable to rotate leading to geometric isomers
as the number of bonds between two atoms increases, the bond ___?
increases in strength but decreases in length
pi bonds
pull the atoms closer together
(triple and double bonds)
triple bonds
the strongest and shortest bonds within the highest energy
single bonds
the longest and weakest bonds with the lowest energy
double bonds
stronger and shorter and higher in energy than single bonds
bond order
number of bonds between two atoms
Bond order table
single 1
double 2
triple 3
how do you calculate bond order
(ex- 1 double bond, 2 single bonds)
see how many bond categorize there are in ur lewis structure so its between 1 and 2 so find an inbetween that so 1/2 = 1.5
