chem quiz chapter 8.3 and 8.4
what are usually soluble in polar substances
Polar molecules and ionic compounds
what is the physical property solubility.
The ability of a substance to dissolve in another substance
what are dipole interactions
The attractions between opposite poles of polar molecules
what determines solubility
The bond type and the shape of the molecules present
polar bond
- electrons shared unequally between atoms - assymmetric molecules
from what does a hybrid result
- from combining 2 of the same type of object, and it has characteristics of both
properties of a trigonal pyramidal
- less repulsions between the bonding pairs of the electrons - the central atom has three bonds and one lone e-. the Lone pair pushes "harder" than the shared pairs
why do structures have atoms maximally spread out?
because electrons around the central nucleus repel each other
why do polar covalent bonds form
because not all atoms that share electrons attract them equally
how is a molecule considered a dipole
because of its 2 partial charges
why do Polar molecules tend to align with an electric field
because polar molecules have greater electron density on one side of the molecule
why is CCI4 a non polar molecule
because the partial charges are balanced
why is the shape of polar H20 bent
because there are two lone pairs of electrons on the central oxygen atom.. it is not symmetric in water, so the molecule has a definite positive end and a definite negative end
why does A covalent bond formed between atoms of different elements not have equal sharing of the electron pair
because there is a difference in electronegativity
what are hybrid levels for?
bonding and molecular structures
In contrast to molecular solids, network solids are what?
brittle, non conductors of heat or electricity, and extremely hard.
how can the character and type of a chemical bond be predicted
by using the electronegativity difference of the elements that are bonded
what is the most common element that undergoes hybridization
carbon
The melting and boiling points of molecular substances are relatively low compared to what
compared to those of ionic substances
molecules are either polar or nonpolar, depending on what
depending on the location and nature of the covalent bonds they contain
what is the strongest intermolecular force
dipole dipole attractions
what is the attraction called between the molecules for a polar substance
dipole dipole force
what is hardness due to in terms of individual molecules?
due to the intermolecular forces between individual molecules
when do atomic orbitals undergo hybridization
during bonding
In a diamond, four other carbon atoms surround what?
each carbon atom
what is the correlation between electron affinity and atomic number as the atomic number increases in a group
electron affinity decreases as atomic number increases within a group
what is the VSEPR theory based on
electron dot structures
The degree of polarity of a bond between any two atoms is determined by consulting a table of what
electronegativities
nonpolar bond
electrons shared equally among atoms - symmetric molecules
When like atoms are joined by a covalent bond, how are the bonding electrons shared
equally
In molecules, where are regions of electron density found?
found around the atom, and its bonds along with unshared electron pairs
what does the character of a chemical bond between atoms depend on
how strongly the bonded atoms attract electrons
what are the weak forces of attraction between individual molecules called
intermolecular forces or van der waals forces.
Many physical properties of covalent molecular solids are due to what
intermolecular forces.
Chemical bonds between atoms or different elements are never completely "..... or....."
ionic or covalent
what is an ionic bond
metal and nonmetals transferring electrons
what is a covalent bond
metals and metals share electrons
are the polar H20 bonds symmetric in water molecules?
no
is bonding often clearly ionic or covalent?
no
nonpolar molecules dissolve only in what type of substances
non polar substances
what is 1 way to distinguish polar from nonpolar molecules
nonpolar molecules are not attracted by an electric field
describe a polar molecules sides
on one side, A polar molecule has a partial negative charge, while on the other side, a polar molecule has a partial positive charge
what is an example of a covalent solid
paraffin
what does the VSEPR theory predict
predicts shapes based on electron pairs repelling (in bonds or by themselves)
what are examples of network solids
quartz and diamond
covalent molecules form what type of solids
relatively soft solids
what are covalent network solids?
solids that are composed only of atoms interconnected by a network of covalent bonds.
what is sp hybridization
- Anything with a linear shape is a result of sp hybridization. - CO and CO2 are common examples. These often result from double and triple bonds.
what is sp3 hybridization
- Anything with a tetrahedral geometry is a result of sp3 hybridization. - Carbon is the most common example
what is sp2 hybridization
- Anything with a trigonal planar shape is a result of sp2 hybridization. - AICI3 and nitrate ion are examples. - Can result from a double bond
what are the properties of a linear shape
- One bond between 2 elements, regardless of bond and number of lone pair e- forms a shape called linear
properties of bent shape
- The central atom has 2 bonds and 2 lone pairs of e-. They push the shared pairs. - the angle between the shared pairs in water is 105 degrees
what is the VSEPR model (the valence shell pair repulsion model)
- The model used to determine the molecular shape
what is electron affinity?
- a measure of the tendency of an atom to accept an electron.
what is the VSEPR model based on
- an arrangement that minimizes the repulsion of shared and unshared pairs of electrons around the central atom
properties of a tetrahedral, and what does it look like
- bonds are all evenly spaced electrons - the central atom contains 4 bonds and no lone pair of e-
properties of trigonal planar
- the central atom has 3 double bonds and no lone pair e-
what is the difference between electronegativity CI vs electronegativity H
0.96
what are the different types of intermolecular attractions
1) dipole dipole attraction 2) hydrogen bonding (H+ O,N, or F) 3) london dispersion attraction... van der waal forces
what is the bond angle of a bent shape
104.5 degrees
what is the bond angle of a trigonal pyramidal
107 degrees
what is the bond angle of a tetrahedral
109.5 degrees
what is the bond angle of a trigonal planar
120 degrees
what is the bond angle of a linear shape
180 degrees
electronegativity H =
2.20
electronegativity CI =
3.16
An electronegativity difference of 1.70 is considered what oercent covalent and what percent ionic
50 %, 50%
what is the relationship between how polar a molecule is and the dipole dipole forces
The more polar a molecule, the stronger the dipole dipole force is
what is a dipole bond
a bond with 2 poles
what is the attraction called between the molecules for nonpolar substances
a dispersion force OR an induced dipole
what is the strongest intramolecular force
a metallic bond
what does unequal sharing result in
a polar covalent bond
what is hybridization
a process in which atomic orbitals are mixed to form new, identical hybrid orbitals
what is a hydrogen bond
a relatively strong intermolecular force where hydrogen is covalently bonded to an electronegative atom, such as oxygen, nitrogen, or fluorine. it is also weakly bonded to an unshared electron pair of another electronegative atom.
what does The scale of electronegativities allow?
allows a chemist to evaluate the electron affinity of specific atoms when they are incorporated into a compound
what is a hydrogen bond
an especially strong intermolecular force that is formed between the hydrogen end of one dipole and a fluorine, oxygen, or nitrogen atom on another dipole
what is an intramolecular force
any force that holds together the atoms making up a molecule or compound.
what is the correlation between electron affinity and atomic number as the atomic number increases in a period
as the atomic number increases within a given period, electron affinity increases.
what types of molecules are usually polar
asymmetric
when do partial charges occur
at the ends of a bond
where is the the more electronegative atom located
at the partially negative end
where is the less electronegative atom located
at the partially positive end
In a covalent compound what is the covalent bond between atoms in molecules like
strong
what is the attraction like between the molecules for polar substances
stronger
what type of molecules are usually non polar
symmetric
what do Large differences in electronegativity indicate?
that an electron was transferred from one atom to another, resulting in bonding that is primarily ionic
what does electronegativity indicate?
the ability of an atom to attract electrons in a chemical bond
what is a dipole dipole force
the attraction of one end of the dipole to the oppositely charged end of another dipole
As the difference in electronegativity increases, what happens
the bond becomes more ionic in character
For identical atoms, which have an electronegativity difference of zero, how are the electrons shared
the electrons in the bond are equally shared between the two atoms and the bond is considered nonpolar covalent, which is a pure covalent bond
why is diamon very hard to break
the four carbon atoms surrounding each carbon atom forms a tetrahedral arrangement of a strongly bonded crystal that is extremely hard to break and has a very high melting point
what do the symbols δ- (partially negative) and δ+ (partially positive) indicate
the polarity of a covalent bond
what is electron density
the probability of an electron being present at a specific location.
what happens when a polar bond forms
the shared pair of electrons is pulled toward one of the atoms
When the atoms in a bond are not the same, how are the bonding electrons shared
unequally
what is the weakest intermolecular force
van der waal forces
what is the attraction between individual molecules like
very weak
For nonpolar substances, what is the attraction like between the molecules,
weak
generally, when do ionic bonds form
when the electronegativity difference is greater than 1.70
in the VSPR theory, the shape of the molecule determines what
whether or not molecules can get enough to react