chem chapter 6 test Flashcards
what is electron affinity
a measure of the energy change when an electron is added to a neutral atom to form a negative ion
what element is usually the central atom in lewis structure
whichever one is written first (except hydrogen will never be central)
what is the electron affinity trend
increases down to up, left to right
what is the atomic radii trend for cations?
anions?
cations: increases up to down, right to left
anions: increases up to down, left to right
why does ionization energy increase left to right? down to up?
because atoms towards the right do not want to gain electrons, they want to lose
because the electrons are held in lower-energy orbitals, closer to the nucleus and therefore are more tightly bound (harder to remove).
shared electrons=
N-A (always even)
what is the difference between electron affinity and ionization energy
electron affinity is a measure of the energy change when an electron is added while ionization energy is the energy required to remove an electron
what is electron affinity opposite of
ionization energy
what is ionization energy
the energy required to move an electron from an atom is ionization energy
why does fluorine have a higher ionization energy than iodine?
it has less electrons-lesser shielding/greater attraction between the electrons and the nucleus
all atoms need 8 electrons, except…
hydrogen needs 2, boron needs 6, beryllium needs 4
why does electronegativity increase down to up and left to right
This occurs due to a greater charge on the nucleus, causing the electron bonding pairs to be very attracted to atoms placed further right on the periodic table
what is the electronegativity trend
increases down to up, left to right
the differences in electronegativities is the classifier of bonds, what are the ranges for each
polar covalent 1.7>or equal to x > or equal to .5
pure covalent x<.5
ionic x>1.7
what is the atomic radii trend
why
increases up to down(valence electron is occupying higher energy level/n value increases making radius larger), increases right to left (number of protons increases (nuclear charge) pulling the electrons in tighter making the radius smaller
the larger the atom is, the (harder/easier) it is for electrons to be removed
easier
ionization energy is always _____ meaning energy is added to the atom to remove the electron
endothermic
H is never involved in a multiple bond
___,____ and ___ often form double and triple bonds
C, N, O
total number of electrons should equal the ______ number
A
isoelectronic means?
same number of electrons
how are ionization energy and atomic radius related
inversely proportional
what is the atomic radii
distance from the center of the nucleus to the “edge” of the electron cloud
usually measured in picometers or angstroms (1x10^-10m)
must be in gas form
center of nucleus to center of nucleus divided by 2
what is shielding effect
inner electrons shield valence electrons from positive charge of the nucleus (protons) (concert analogy)
______ do not have ionic radii because they do not form ions
noble gases
when hydrogen becomes an ion, it is just an ____
electron
number of bonds=
S/2
why do elements in the same family generally have similar properties
they have the same amount of valence electrons
what is electronegativity
holding onto its own electrons and taking other ones
what is the metallic trend
increases up to down, right to left
the number of available electrons is equal to the _____________
number of valence electrons of the atom
what is the ionization energy trend
increases down to up, left to right
why does electron affinity increase down to up, left to right
because the electrons added to energy levels become closer to the nucleus, thus a stronger attraction between the nucleus and its electrons
covalent bonds are the _____ of electrons between two ________, one cation and one anion
sharing, nonmetals
if a molecule has 4 total electron domains
what will it look like with 0,1,2,3 lone pairs on the central atom
tetrahedral, trigonal pyramidal, bent, —
of hybrid orbitals formed= what
of domains on the central atom
3 electron domains means _____ electron geometry and _____ bond angles
trigonal planar 120
equal sharing in covalent bonds means ____
unequal sharing means _____
nonpolar (do not have opposite ends), polar
if a molecule has 2 total electron domains
what will it look like with 0,1,2,3 lone pairs on the central atom
linear—-
what is bond polarity determined by
electronegativity difference in the bond (dipole)
double bonds only exist in ___
planes
2 electron domains means _____ electron geometry and _____ bond angles
linear, 180
how can you tell if a bond is polar
polar bonds have at least one of these two characteristics
one or more lone pairs on center atom (dipoles will angle)
if you have different atoms connected to your center (different electronegativities)
4 electron domains means _____ electron geometry and _____ bond angles
tetrahedral, 109.5
has a magnitude
has a value
has a direction
ex) velocity
vector
if a molecule has 6 total electron domains
what will it look like with 0,1,2,3 lone pairs on the central atom
octahedral, square pyramidal, square planar, T-shaped
6 electron domains means _____ electron geometry and _____ bond angles
octahedral 180/90
if dipoles cancel, you have a ______ bond
how do dipoles cancel
nonpolar
same magnitude, towards or away from each other
ionic bonds are a ____ of electrons between a ______ (which loses electrons and becomes a _____) and a _________ (which gains electrons and becomes a _______)
transfer, metal, cation, nonmetal, anion
5 electron domains means _____ electron geometry and _____ bond angles
trigonal bipyramidal 180/120/90
if a molecule has 5 total electron domains
what will it look like with 0,1,2,3 lone pairs on the central atom
trigonal bipyramdial, see-saw, T-shaped, linear
how is molecule polarity determined
whether the dipoles cancel or if there is a resultant
how do you indicate if a bond is ionic, polar, or nonpolar
ionic- >1.7
polar- .5-1.7
nonpolar- 0-.4
if a molecule has 3 total electron domains
what will it look like with 0,1,2,3 lone pairs on the central atom
trigonal planar, bent, linear,–
what is the dipole?
electronegativity inbalance, represented by arrows drawn towards more electronegative element
where electrons are found within the bond
explain AXE notation
A-central atom
X- atoms bonded to central atom
E- lone pairs on central atom only
example) PF5’s notation would be AX5
lone pairs on the central atom will result in a bond angle that is ____________ ideal
less than
electrostatic attractive force between the partially positive charged hydrogen end of an O-H, N-H, or F-H bond and the negative charge of a lone pair on an O, F, or N
hydrogen bonding
electrostatic attractive force between any two molecules
london dispersion force
electrostatic attractive force between two polar molecules
dipole-dipole
molecules with an indicated charge on in ____ with the charge drawn on the ___
brackets, outside
what is the more polar of the following two bonds with the indicated electronegativity inbalance
B—>F (2.0)
B—>I (0.5)
B—>I because B—>F(2.0) is ionic
choose the orbital in which an electron would experience the highest effective nuclear charge (least shielded) and the highest ionization energy
Na (3s) Mg (3s) Al (3p) P (3p) S (3p)
Mg (3s)
closest to the nucleus
atoms are ____ stable alone than combined with other atoms
why
less
they have to use energy to combine therefore become more stable
bond polarity refers to the equal (___) or unequal (___) sharing of electrons
molecular polarity refers to the symmetry(___) or asymmetry(___) of a molecule
nonpolar, polar, nonpolar, polar
what makes a bond polar (covalent)
if the bond occurs between two ___ nonmetals
different
what makes a molecule asymmetrical?
if there are ____________ around the central atom and/or if the surrounding atoms are different ______
lone pairs, elements
smallest unit formula unit exists as solids, usually crystal shapes have high melting points most dissolve in water melted or dissolved in water conduct electricity fixed + and - parts; anions and cations examples KCL, NaF, KNO3
ionic compounds
smallest unit molecule
exists as liquids, gases, or non-crystal solids
have low melting points
few dissolve in water
melted or dissolved in water does not conduct electricity
may have slightly + and - parts or totally neutral
examples NH3, CO2, CH4
covalent (molecular) compounds
ionic compounds minimize PE by organizing into _____
crystals
