Chem Honors Unit 5 Test
What are the properties of Network Covalent solids? (M.P, Conductivity, solubility, physical properties, etc.)
-All "molecules" are held together by covalent bonds -Very high M.Pt. -Hard -Brittle -Doesn't conduct in any state -Soluble
What are the properties of metallic solids? (conductivity, M.P, state at room T, physical properties, solubility)
-Conduct in all states -generally high M.Pt -usually solids at room temperature (except for mercury) -malleable and ductile (bendy and stretchy) -Insoluble
What are some properties of ionic compounds.
-Crystal Lattice structure -High melting point -Brittle -Conductive as liquid and aqueous solution 9not as a solid) -Many are soluble in water
What are the IMF solubility rules?
-IMF's mix -like dissolves like (polar dissolves polar) -H-bonds w/ H₂O improves solubility
What are the physical properties of molecules with strong IMF's
-Molecules with strong IMF's are harder to separate -Strong IMF's result in a high surface tension -Different substances with similar IMF's tend to mix
How do covalent bonds form?
Covalent bonds form as a result of overlapping electron clouds (orbitals). This allows atoms involved to share electrons between them.
How are covalent bonds formed?
Covalent bonds formed as a result of overlapping electron clouds (orbitals), which allows the atom to share electrons
What are some examples of metallic solids?
Cu, Na, Hg
Which substance, CH₄ or C₂H₅OH would be most soluble in water? Briefly explain.
C₂H₅OH is more soluble because H-bond dissolves H-bond.
Which would you expect to be the most volatile HCL or C₂H₆? Briefly explain.
C₂H₆ is non-polar so it has weaker IMF's so its evaporation is higher, so therefore it's more volatile
What does metallic bonding look like?
DELOCALIZED ELECTRONS!!!!
What kind of bonding occurs between particles of metallic solids?
Delocalized electrons (a.k.a non-directional covalent)
What are some examples of network covalent solids?
Diamond, Graphite, Silicon Dioxide
What type of bonding between particles occurs in network covalent solids?
Directional covalent (it's like one giant molecule)
Which particles occupy the lattice points of molecular solids?
Discrete molecules
What kind of bonding occurs between particles in noble gases?
Dispersion forces
What kind of bonding occurs between particles in molecular solids?
Dispersion or dipole-dipole of H-bonding
What are the properties of molecular solids? (conductivity, B.pt, state at room temp, solubility, etc.)
Don't conduct in any phase, generally low B.Pt, can be a gas, liquid or solid at room T, most are insoluble in water, but are soluble in non-polar solvents.
What happens in covalent bonding?
Electrons are shared when atomic orbitals overlap (forming "molecular orbitals"
What happens in ionic bonding?
Electrons are transferred from the more metallic element to the less metallic element, to form charged ions that then stick together.
What happens in non-polar covalent bonding?
Equal sharing of electrons. Mainly occurs between two of the same metallic element (eg. diatomics)
What is the formula, lewis structure, shape and molecular polarity of Carbon tetrachloride?
Formula: CCl₄ Shape: Tetrahedral Molecular: NP
What is the formula, lewis structure, shape and molecular polarity of Hydrogen Fluoride?
Formula: HF Shape: Linear Molecular: →
What is the formula, lewis structure, shape and molecular polarity of Water?
Formula: H₂O Shape: Bent Molecular Polarity: ↑
What is the formula, lewis structure, shape and molecular polarity of Nitrogen trichloride?
Formula: NCl₃ Shape: Trig Pyramidal Molecular: ↑
What is the formula, lewis structure, shape and molecular polarity of phosphorus trichloride?
Formula: PCL₃ Shape: Trigonal Pyramidal Molecular Polarity: ↑
What is the formula, lewis structure, shape and molecular polarity of Sulfate ion?
Formula: SO₄²⁻ Shape: Trigonal Pyramidal Molecular Polarity: Since ions are charged, polarity is not applicable!
What is the formula, lewis structure, shape and molecular polarity of Xenon tetrafluoride?
Formula: XeF₄ Shape: Square Planar Molecular Polarity: NP
What are some examples of noble gases?
He, Ar
What are the properties of ionic solids? ( M.Pt, state at room temperature, conductivity, solubility, physical properties, etc.)
High M.Pt, always solids at room temperature, solids don't conduct electricity but molten and aqueous phases do, many are soluble in water, brittle
A shape has a total of 6 electron pairs, so what is the name of its electronic geometry and what does it look like?
Octahedral
What is the polarity, force of attraction, force of attraction and relative strength of Dispersion forces?
Polarity of Molecule: Non-polar molecule Force of attraction: Force caused by attraction of "temporary" or "induced" dipoles. Relative Strength: Weak
What is the polarity, force of attraction, force of attraction and relative strength of Dipole-Dipole forces?
Polarity of Molecule: Polar Force of Attraction: Force caused by attraction of permanent molecular dipoles. Relative Strength: Stronger
What is the polarity, force of attraction, force of attraction and relative strength of Hydrogen bonding?
Polarity of Molecule: Polar Force of Attraction: Force caused by attraction of permanent molecular dipoles. Specifically, for molecules that contain a Hydrogen covalently bonded to an N, O, or F within the molecule. Relative Strength: Strongest
What is the lewis structure, shape and molecular polarity of CH₃COOH?
Shape: Bent (around the oxygen) Molecular Polarity: NP
What is the lewis structure, shape and molecular polarity of C₄H₁₀?
Shape: Tetrahedral (around left carbon) Molecular Polarity: NP (ignore hydrogens)
What type of bond is this? Na and Br
ionic
What is a resonance structure?
bonding that describes the delocalization of electrons within molecules. It compares and contrasts two or more possible Lewis structures that can represent a particular molecule.
What are intermolecular bonds?
bonds BETWEEN molecules
What are intramolecular bonds?
bonds between atoms WITHIN molecules
What type of bond is this? N and O
covalent
In a polar covalent bond, which type of elements are electrons pulled slightly towards?
elements with high electronegativity
Is bond breaking exothermic or endothermic?
endothermic
Is bond forming exothermic or endothermic?
exothermic
True or False: When in the solid state, an ionic compound has particles with different shapes, but all ionic compound particles have the same shape.
false; when in the solid state, an ionic compound has particles with the SAME shape, but all ionic compound particles have a DIFFERENT shape.
What are intramolecular forces?
forces that hold atoms together in a molecule
What differentiates a bent molecule from a linear one?
linears have no lone pairs, while bents have one or two lone pairs
If a solid is not brittle and conducts as a solid it is.....
metallic
What type of bond is this? Mg and Mg
metallic
There are two types of covalent bonds. What are they?
polar covalent bonds and non-polar covalents
Put these bonds in order of strength: Single bond, double bond, triple bond
single < double < triple
What is the molecular shape of NH₄⁺
tetrahedral
In a Lewis Dot structure, arrows with arrowheads on both sides symbolize that the diagrams are equivalent. However, in real life, molecules with resonance don't have two equivalent ways of being formed, and don't have double bonds on either side of them. In reality, what is happening to the electrons?
the delocalization of the electrons allows the electron(s) to move between the bonds so quickly that it seems as if the electron is in multiple bonds at one time
Put these bonds in order of length: Single bond, double bond, triple bond
triple< double< single
What are two ways to make a substance boil (assume external pressure is 1 atm)?
1) Increase the temperature 2) lower the external pressure till it = the VP
Fill in the blanks: So __ Calcium atom(s) transfer(s) ___ total electrons to __ Bromine atom(s) to form ions. The calcium ion has a charge of ____ and is (smaller/larger) than the original calcium atom. The bromide ion has a charge of ____ and is (smaller/larger) than the original bromine atom.
1, 2, , 2, +2, smaller, -1, larger
Fill in the blanks: So ____ Aluminum atom(s) transfer(s) ____ total electrons to ___ Nitrogen atom(s) to form ions. The aluminum ion has a charge of _____ and is (smaller or larger) than the original aluminum atom. The nitride ion has a charge of _____ and is (smaller or larger) than the original nitrogen atom.
1, 3, 1, +3, smaller, -3, larger
What is the formula of the ionic compound that would form between: Calcium and Oxygen
2CaO
What is the formula of the ionic compound that would form between: Rubidium and Iodine
2RbI
Which substance would you expect to have the highest boiling point, Neon or Argon? Briefly explain.
Argon: ↑Electrons ↑IMF ↑Boiling Point
What particles occupy the lattice points for network covalent solids?
Atoms
Which particles occupy the lattice points in noble gases?
Atoms
Rank these IMF's in order of increasing IMF strength: NH₃, CH₄, CH₃CH₂OH, H₂, HCl
H₂<CH₄<HCl<NH₃<CH₃CH₂OH
What kind of bonding occurs between particles in ionic solids?
Ionic (attraction between cations and anions)
What particles occupy the lattice points in ionic solids?
Ions (alternating cations and anions)
When an ionic bond is formed, what happens to the non-metallic element (in size)? What does it become?
It becomes an anion (negative charge), increasing in size
What is molecular geometry?
It describes the arrangement of bonded atoms in a molecule. Lone pairs on the central atom are important in influencing molecular shape.
A shape has a total of 2 electron pairs, so what is the name of its electronic geometry and what does it look like?
Linear
What particles occupy the lattice points of metallic solids?
Metal atoms
What happens in metallic bonding?
Metal atoms (cations) are glued together by delocalized, mobile electrons.
What allows metallically bonded molecules from breaking?
Metallically bonded elements are maleable; the positive cations and the negative anions prevent the solid metal from snapping when bent.
What do solids look like?
Most solids exist as some kind of lattice, except things like glass which are amorphous (no regular structure).
What are some examples of Ionic solids?
NaCl, CS₂O
If a solid has a high M.pt, does not conduct as a solid or melted, and is insoluble in water it is.....
Network covalent
If a solid has a very low melting point, and exhibits the weakest type of IMF it is.....
Noble gas
Why can't noble gases be molecular solids?
Noble gases have "molecules" that are atoms-hence the distinction!
What is a Hydrogen bond caused by?
Occurs between polar molecules that have a hydrogen covalently bonded to an N, O, or F within the molecule.
What are some examples of molecular solids?
Sugar, H₂O, N
What are some factors that affect vapor pressure?
Temperature (Temp↑, Evap↑, VP↑) and IMF (IMF↑, Evap↓ VP↓)
What are dispersion forces caused by?
Temporary (or induced or momentary) molecular dipoles. This is the random fluctuation in electron densities in the molecule.
A shape has a total of 4 electron pairs, so what is the name of its electronic geometry and what does it look like?
Tetrahedral
What is the "normal" boiling point?
The "normal" boiling point is when the external pressure is 1 atm.
What is Boiling Point?
The boiling point of a liquid is the temperature at which its vapor pressure is equal to the external pressure.
What is organic chemistry?
The chemistry of living things. It revolves around molecules that contain carbon. These molecules mainly contain carbon and hydrogen (hydrocarbons), but can include other elements like nitrogen and oxygen.
How are intramolecular bonds created? In short terms, what is it dependent on?
The creation of bonds always involves the attraction between the nuclear charge (positive) of bonded atoms in correlation to the electrons (negative); in short, it is dependent on electrongeativity
What does it mean when electrons are delocalized? How does it relate to the conductivity of electricity of metallically bonded elements?
The electrons are spread out in a sea of electrons, not belonging to one specific atom (they are not local to one specific atom anymore)-the sea of electrons move when electricity flows through them, and immediately stop moving once electricity flow stops.
In some cases, there are instances where the octet rule is broken. Which elements are allowed to have less than eight electrons in their Lewis Dot structure?
The elements to the left of carbon, consisting of boron, beryllium, and lithium can have less than eight valence electrons
When does the bond forming overlap occur (what happens to the potential energy and the distance)?
The overlap occurs when the attractive and repulsive forces are balances and potential energy is at a minimum; this is the only time atoms can bond
What is Vapor pressure?
The pressure exerted by the vapor of a substance at a given temperature. Typically, it is measured by putting a liquid into an evacuated container and the liquid is allowed to reach equilibrium where the pressure is measured. (directly proportional to the number of gas particles present).
What determines the strength of a chemical bond? What equation/law is related to the determining factor?
The size of the attractive force (related to Coulombs's Law)
How does electronegativity effect bonding?
The type of bonding present in a compound depends on the relative electronegativity of the atoms present. If the electronegativity of the bonded atoms is the same, then it will have a non-polar covalent bond.
How are atoms of metallic elements arranged in a metallic bond?
They are arranged with a matrix of metal cations and a sea of electrons that do not belong to one specific atom
A shape has a total of 5 electron pairs, so what is the name of its electronic geometry and what does it look like?
Trigonal bipyramidal
A shape has a total of 3 electron pairs, so what is the name of its electronic geometry and what does it look like?
Trigonal planar
What happens in polar covalent bonding?
Unequal sharing of electrons. Mainly occurs between two different non-metallic elements.
What are the properties of noble gases? (B.pt, state at room temperature, conductivity, solubility, etc.)
Very low B.Pt, Gases at room T, don't conduct in any phase, insoluble in water but soluble in non-polar solvents
Why are ionic compounds brittle?
When bent, alternating layers shift, causing like charge to align and resulting in electron repulsion-this causes the substance to "snap"
If a solid has low melting point crystals and some are soluble in water it is....
a molecular solid
Sketch a VP vs. Temp graph below for C₄H₁₀, H₂O, CH₃Cl, and CO₂
answers on packet (no answer found on the internet) Go check there, or don't, I don't really care.
If molecules are polar when lone pairs of electrons are present, which molecular shape(s) will be polar?
bent and trigonal pyramidal