• The neutron has a mass Answersimilar10000 times higher10000 times smaller than the proton, and a Answermore positiveequally positiveneutralequally negativemore negative charge 
• The electron has a mass Answersimilar10000 times higher10000 times smaller than the proton, and a Answermore positiveequally positiveneutralequally negativemore negative charge

Consider two charges of the the same sign at a short distance (+)----(+) (diagram "e")

• Their potential energy is always Answerpositivenegativezero and the force among them always Answerattractiverepulsive
  
• The farther away they are to each other, their potential energy becomes Answermore positiveless positiveless negativemore negative, therefore, the system becomes Answermore stableless stable
• In the plot above, knowing that each charge diagram (a to h) correspond to one point in the graph, the potential energy of the two discussed charges is represented by point Answer12345678

There are different areas of the electromagnetic spectrum. In alphabetical order they are:

• Gamma rays
  
• Infrared
• Microwaves
• Radiowaves
• Ultraviolet
• Visible light
• X rays

If we were to rank a photon in decreasing order of energy, 1 being the most energetic photon and 7 the least energetic photon, a microwave photon would be in position number Answer1234567.

If we were to rank a photon in decreasing wavelength, 1 being the longest wavelength and 7 the shortest one, an ultraviolet photon would be in position number Answer1234567

If we were to rank a photon in decreasing frequency, 1 being the highest frequency and 7 the lowest, an infrared photon would be in position number Answer1234567

The isotope ⁴¹K^(-) has Answer protons, Answer neutrons, and Answer electrons. According to the periodic table, the most common neutral isotope of potassium has Answer protons, Answer neutrons, and Answer electrons.

We analyze with mass spectrometry the isotopic abundance of a sample containing one single element. The sample may contain the natural abundance of isotopes found on earth, or a slightly different combination of those same isotopes.
Here the "relative abundance vs mass" is represented.

• The most common isotope in this sample has Answer neutrons (write an integer without spaces)
  
• The sample measured contains a natural abundance of isotopes Answertruefalse
  (or at least it is consistent with the molar mass shown in the periodic table)
  
• The symbol of this element is Answer (write the symbol of the element with proper Uppercase-Lowercase without spaces: H, He, Li, B, )

• One mole is defined as
  AnswerThe number of grams of one particleThe number of particles in one gram6.023x10^(23) particlesThe grams of 6.023x10^(23) particles
• The molar mass is defined as
  AnswerThe number of grams of one particleThe number of particles in one gram6.023x10^(23) particlesThe grams of 6.023x10^(23) particles
  
  

• Ten atoms of carbon have an approximate mass of the order of Answer10^2310^(-23)10^110^2 grams
• Ten moles of carbon have an approximate mass of the order of Answer10^2310^(-23)10^110^2 grams
• Ten grams of carbon have an approximate number of carbon atoms of the order Answer10^2310^(-23)10^110^2 atoms.

Comparing the atoms Bromine Br and Iodine I

• The atom Br has Answermorelessthe same protons than I
• The atom Br has Answermorelessthe same electrons than I
• The effective nuclear charge (Zeff) is the positive charge that the valence electrons feel taking into account the electron shielding. In this sense, Zeff for valence electrons in Br will be Answerhigherlowerthe same than I.
  
• The principal quantum number "n" that determines that size of the orbital of the valence electrons for Br is Answerhigherlowerequal than "n" for the valence electrons of I.
  
  
• For all the above, we should expect the valence electrons of Br to be Answermorelessequally attracted to its nucleus than the valence electrons of I, the ionization energy of Br should be Answersmallerlargerequal, and its radius should be Answersmallerlargerequal than I's.

Consider the electronic orbitals of the atom of iodine

• The orbital 6s has a Answerhigherlower energy than the orbital 5p
• When an electron transfers from 5p to 5d a photon will be Answerabsorbedemitted
• The frequency of the photon involved in the 5p -> 6p transition will be Answerhigherlower than the frequency of the photon for the 5p -> 5d transition.
• The wavelength of the photon involved in the 5d -> 5p transition will be Answerlongershorter  than the wavelength of the photon for the 6p-> 5p transition.

Suppose the three waves below are electromagnetic radiation waves from the visible range, one blue light, one red, and one green.
Note: in a real representation the three waves would be more similar, here, for clarity reasons, are made more distinctive.

• The most intense (brightest) light is Answerblueredgreenthey are all the same
  
• The highest frequency light is Answerblueredgreenthey are all the same
  
• The longest wavelength is AnswerABCthey are all the same
  
• The fastest wave is Answerblueredgreenthey are all the same

All the atoms in a conjugated system are Answertrigonal planar-sp2tetrahedral-sp3linear-sp. The fewer electrons involved in the conjugated system, the energy gap between HOMO and LUMO will be Answersmallerlargerno effect and therefore the wavelength of the photon involved in the absorption process will be Answerlongershorter. Being the energy of the HOMO Answerhigherlower than LUMO's, the process of absorption will take place when an electron goes from AnswerHOMO to LUMOLUMO to HOMO.

Considering the molecule on the left, there are Answer carbon atoms forming a conjugated system. The picture on the right Answerisis not a resonance form of the picture on the left.

• The central atom of phosphorus trihydride has a hybridization of Answersp3sp2spnone of the above. The angle between the central atom and its surrounding atoms is approximately Answer90109.5120180 because it has a Answerlineartrigonal planartetrahedraltrigonal bipyramidaloctahedral geometry. This compound Answerdoesdoes not have a molecular dipole.
• The central atom of boron trifluoride has a hybridization of Answersp3sp2spnone of the above. The angle between the central atom and its surrounding atoms is approximately Answer90109.5120180 because it has a Answerlineartrigonal planartetrahedraltrigonal bipyramidaloctahedral geometry. This compound Answerdoesdoes not have a molecular dipole.
• The central atom of carbon dioxide has a hybridization of Answersp3sp2spnone of the above. The angle between the central atom and its surrounding atoms is approximately Answer90109.5120180 because it has a Answerlineartrigonal planartetrahedraltrigonal bipyramidaloctahedral geometry. This compound Answerdoesdoes not have a molecular dipole.
  

The compound on the left has:
Answer hydrogens, Answer sp3 carbons, and  Answer sp2 carbons.
A total of Answer groups of non-equivalent hydrogens (or number of signals on ¹H-NMR)
A total of Answer groups of non-equivalent carbons (or number of signals on ¹³C-NMR)

The compound on the right has: 

Answer hydrogens, Answer sp3 carbons, and  Answer sp2 carbons.
A total of Answer groups of non-equivalent hydrogens (or number of signals on ¹H-NMR)
A total of Answer groups of non-equivalent carbons (or number of signals on ¹³C-NMR)

• Carbon diamond solid is a Answermolecularionicmetalliccovalent network solid, and when it melts the forces that need to break are Answercovalent bondsionic bondsmetallic bondsintermolecular forces. This is why at room temperature this compound will most likely be a Answersolidliquid or gas.
• Nitrogen trifluoride solid is a Answermolecularionicmetalliccovalent network solid, and when it melts the forces that need to break are Answercovalent bondsionic bondsmetallic bondsintermolecular forces. This is why at room temperature this compound will most likely be a Answersolidliquid or gas.
• Calcium fluoride solid is a Answermolecularionicmetalliccovalent network solid, and when it melts the forces that need to break are Answercovalent bondsionic bondsmetallic bondsintermolecular forces. This is why at room temperature this compound will most likely be a Answersolidliquid or gas.

• Fructose and Glucose are Answermonosaccharidesdisaccharidespolysaccharideslipidpeptidesamino acidsnucleic acidsnucleotidenitrogenous base they have Answernoseveralone chiral center(s).
• Fructose has a Answerketonealdehydecarboxylicesteramideamine functional group. When it cycles it typically forms a Answerthreefourfivesixseveneight member ring.
• Glucose has Answerketonealdehydecarboxylicesteramideamine functional group. When it cycles it typically forms a Answerthreefourfivesixseveneight member ring.
• A peptide is a sequence of Answermonosaccharidesdisaccharidespolysaccharideslipidpeptidesamino acidsnucleic acidsnucleotidenitrogenous base. A peptide will have Answeronenonemany chiral center(s), and it will be characterized by the Answerketonealdehydecarboxylicesteramideamine functional group.
• A triacyl glyceride is a type of Answermonosaccharidesdisaccharidespolysaccharidespeptidesamino acidsnucleic acidsnucleotidelipidnitrogenous base and is characterized by the Answerketonealdehydecarboxylicesteramideamine functional group.
• A ribose is a type of Answermonosaccharidesdisaccharidespolysaccharidespeptidesamino acidsnucleic acidsnucleotidelipidnitrogenous base and it is an essential component of Answermonosaccharidesdisaccharidespolysaccharidespeptidesamino acidsnucleic acidslipidnitrogenous base and it has Answernoseveralone chiral center(s).

Different factors may affect the boiling point of a substance.

I) A chemical bond (ionic, metallic, or covalent) is much stronger than intermolecular forces
II) Hydrogen bonds are stronger than dipole-dipole
III) Hydrogen bonds are stronger than London forces
IV) Dipole-dipole interactions are stronger than London forces
V) The heavier a compound is, the higher the boiling point
VI) The less branched/more linear a compound is the higher the intermolecular interaction.

However, only one factor will be the most important one. You are already given what compound has a higher boiling point, based on this information you must identify the most important factor in each case.

• Propanoic acid has a higher boiling point than tetrafluoromethane because AnswerIIIIIIIVVVI
• ethyl amine has a higher boiling point than butane because AnswerIIIIIIIVVVI
• Calcium fluoride has a higher boiling point than fluoromethane because AnswerIIIIIIIVVVI

Solid substances may present different types of interactions:

I) Ionic bond             II) Covalent bond     III) Metallic bond
IV) Hydrogen bond   V) Dipole-dipole      VI) London Dispersion

Identify the strongest type of interaction that breaks when the following substances melt. Write I-VI.

• When pentanal melts the strongest force breaking is AnswerIIIIIIIVVVI.  It Answerisis not a solid at room T.
• When Carbon graphite melts the strongest force breaking is AnswerIIIIIIIVVVI.  It Answerisis not a solid at room T.
• When Lithium chloride melts the strongest force breaking is AnswerIIIIIIIVVVI.  It Answerisis not a solid at room T.
  

Consider an ideal gas in a container:

• Compressing the walls of a container will result in the volume to decrease and therefore the pressure will Answerdecreaseincreaseremain constant
  
• When cooling down the gas in a rigid container its temperature will decrease and its pressure will Answerdecreaseincreaseremain constant
  
• When cooling down the gas of a balloon the temperature will decrease and the volume will Answerdecreaseincreaseremain constant
  
• After blowing air into a party balloon, the number of moles will increase, the volume will Answerdecreaseincreaseremain constant  and that is because the pressure will Answerdecreaseincreaseremain constant.

• The heat capacity of a substance describes
  AnswerThe heat per unit of temperatureThe temperature per unit of heatThe mass per unit of temperatureThe mass per unit of heatThe heat per unit of massThe temperature per unit of mass
• We mix 10 moles of diethyl ether at T=20 ^oC with 10 moles of propanol T=10^oC. The final temperature will be Answerbelow 15equal to 15above 15
• If we consider propanol our system, the process of mixing will be Answerisothermicexothermicendothermic

The heating curve for equal moles of solid substance A and B are shown below

• The y-axis represents Answerheatmassmolar heat capacitytemperature and the x-axis represents Answerheatmassmolar heat capacitytemperature
  
• The molar heat capacity of the solid A is Answerhigherlowersimilar than the molar heat capacity of solid B.
• The melting point of A is Answerhigherlowersimilar than the melting point of B.
• The molar enthalpy of freezing of A is a Answerpositivenegativezero value, and it is, in absolute value, Answerlargersmallersimilar than the molar enthalpy of melting of B.

For each of the substances below, write the products of a balanced dissociation in water. Write first the cation then the anion, add one space between the plus sign, and no (aq) phases. If the substance is not ionic (even if it's acid/base) write the word none. For example: for sodium carbonate you would write as answer: 2Na^+ + CO3^2- (pay attention to spaces and the sequence of characters)

• The products of dissociation of one mole of calcium iodide are Answer
• The products of dissociation of one mole of copper(I) sulfide are Answer
• The products of dissociation of one mole of iron(III) nitrate are Answer 

The four qualitative vapor pressure vs T curves for the liquids CH₃CH₂CH₃, CH₃CH₂CH₂Cl, CH₃CH₂CH₂CH₃, and CH₃CH(CH₃)CH₃

• At a given T, the compound A has the Answerhighestlowest vapor pressure and it is most likely AnswerCH3CH2CH3CH3CH2CH2ClCH3CH2CH2CH3CH3CH(CH3)CH3
  
• At a given T, the compound D has the Answerlargestsmallest enthalpy of vaporization and it is most likely AnswerCH3CH2CH3CH3CH2CH2ClCH3CH2CH2CH3CH3CH(CH3)CH3
  
• The second lowest boiling point corresponds to the curve AnswerABCD and it is most likely the compound AnswerCH3CH2CH3CH3CH2CH2ClCH3CH2CH2CH3CH3CH(CH3)CH3