Unit 1 Flashcards
Give the meaning of the term relative atomic mass.
average mass of all the atoms in an element compared to 1/12th the mass of a carbon-12 atom
Ions in a mass spectrometer are deflected using…
Magnetic field
Describe how the ions in a mass spectrometer are detected.
(Ions hit) plate/detector causing movement of electrons or (ions hit) plate/detector accept electrons
current generated
A second mass spectrum was recorded for the same sample of silicon.
The energy of the electrons from the electron gun was higher for this second spectrum.
Similarities:
(Some) peak(s) at same m/z
same sample / element (is being ionised and detected)
Differences:
Additional peak(s) at ½ m/z value
Two electrons knocked out
Van der Waals’ forces exist between all molecules.
Explain how these forces arise.
Electron movement in first molecule / temporary dipole
Induces a dipole in another molecule
(induced-temporary) attraction or δ+ attracts δ- in different/adjacent molecules
Methanol (CH3OH) and methanethiol (CH3SH). ) Explain, in terms of their intermolecular forces, why the boiling points of these compounds are different.
(methanol) H-bonds / hydrogen bonding
(methanethiol) dipole-dipole forces or van der Waals
H-bonds are a stronger / are the strongest IMF
Suggest how a mixture of methanol and methanethiol could be separated.
(Fractional) distillation
Suggest why methaneselenol (CH3SeH) has a higher boiling point than methanethiol (CH3SH).
(Methaneselenol is a) bigger molecule
With stronger/more vdw forces between molecules
Solid Cu2(OH)2CO3 is added to an excess of dilute hydrochloric acid. Suggest one observation that could be made during the reaction.
effervescence
State what is meant by the term empirical formula.
Simplest ratio of atoms of each element in a compound
Identify the homologous series to which octane belongs.
Alkanes
Complete combustion products.
Carbon Dioxide and Water
Incomplete combustion products.
Carbon Monoxide or Carbon (soot) and Water
Name the type of cracking that produces a high yield Alkenes.
Give two conditions required for this process.
Thermal
High pressure (70 atms)
and
High temperature (500 degrees Celsius)
State and explain the general trend in first ionisation energy across Period 3.
General increase
Greater nuclear charge / more protons
Same shielding / electrons added to same shell
Stronger attraction (from nucleus) for outer electron(s)
Give one example of an element which deviates from the general trend in first ionisation energy across Period 3.
Explain why this deviation occurs.
Sulfur / S (lower than P)
(outer) electrons in (3)p orbital begin to pair
repel
Table 3 shows successive ionisation energies of an element Y in Period 3.
Identify element Y.
Explain your answer using data from Table 3.
Sulfur / S
Large jump after 6th
Identify the Period 3 element that has the highest melting point.
Explain your answer by reference to structure and bonding.
Silicon
Giant covalent structure
Covalent Bonds
Many / strong (covalent bonds) need lots of energy to break
Explain whether the first method or the second method of production of phosphoric acid has the higher atom economy.
You are not required to do a calculation
Method 1
No other products formed
State the element in Period 3 that has the highest first ionisation energy.
Explain your answer.
Argon / Ar
Large(st) number of protons / large(st) nuclear charge
Same amount of shielding / same number of shells / same number of energy levels
Suggest the element in Period 3 that has the highest electronegativity value.
Chlorine
Suggest what might cause the relative atomic mass of this sample to be different from the relative atomic mass given in the Periodic Table.
some isotopes absent/missing
Write an equation for the reaction that occurs when a tellurium ion hits the detector.
Te+ + e(–) –> Te
The mass spectrum of tellurium also has a small peak at m/z = 64.
Explain the existence of this peak.
2+ ion formed / 2 electrons removed From 128 (Te)
Predict whether the atomic radius of two isotopes are different or the same.
Explain your answer.
Same
(Each isotope has the) same number of protons
Give the name of the type of crystal structure shown by silicon dioxide.
Giant covalent
Suggest why silicon dioxide does not conduct electricity when molten.
No delocalised electrons
Suggest how a student doing this experiment could check that all the water had been removed.
re-heat
check that mass is unchanged
Suggest a value for the H–O–O bond angle.
100 degrees
State the strongest type of interaction that occurs between molecules of hydrogen peroxide and water.
Hydrogen bonds
Explain, in terms of electronegativity, why the boiling point of H2S2 is lower than H2O2.
Electronegativity of S lower than O
No hydrogen bonding between H2S2 molecules only van der Waals
Give the meaning of the terms saturated and hydrocarbon as applied to saturated hydrocarbons.
Saturated – single carbon-carbon bonds only
Hydrocarbon – contains carbon and hydrogen (atoms) only
Explain why the sulfur compounds found in crude oil should be removed from the fractions before they are used for central heating fuel.
SO2 produced
Which causes acid rain
Suggest one important substance manufactured on a large scale from propene.
polypropene
Sodium azide has a high melting point.
Predict the type of bonding in a crystal of sodium azide.
Suggest why its melting point is high.
Ionic
Oppositely charged ions / Na+ and N3– ions
lots of energy needed to overcome (strong) attractions (between ions)
Give the formula of a molecule that has the same number of electrons as the azide ion.
CO2
Which is the correct formula of magnesium azide?
MgN6
Which one of the following is a fundamental particle that would not be deflected by an electric field? A electron B neutron C proton
B neutron
State why isotopes have similar chemical reactions.
the have the same electron configuration
Second ionisation energy equation for boron.
B+(g) –> B^2+(g) + e(–)
Explain why the second ionisation energy of boron is higher than the first ionisation energy of boron.
Electron being removed from a positive ion (therefore need more energy) to remove the electron
Suggest a name for this type of reaction that iron(III) nitrate undergoes.
(Thermal) decomposition
Suggest why the iron(III) oxide obtained is pure. Assume a complete reaction.
because there are no other solid/liquid products
State the block in the Periodic Table that contains nickel.
d (block)
Explain, in terms of its structure and bonding, why nickel has a high melting point.
Contains positive (metal) ions and a sea of electrons Strong metallic bonds
Explain why nickel is ductile (can be stretched into wires).
sheets of atoms can slide over one another
The following equation shows how anhydrous nickel(II) chloride can be obtained from the hydrated salt using SOCl2.
Identify one substance that could react with both gaseous products.
CaCO3
Name the strongest attractive force between two ammonia molecules.
Hydrogen bonds
State how the bond between ammonia and boron trichloride is formed.
Lone pair is donated to B(Cl3)
Give the meaning of the term electronegativity.
The power of an atom to attract electrons towards itself in a covalent bond.
Give the name of the substance from which paraffin is obtained.
State the name of the process used to obtain paraffin from this substance.
Crude oil
Fractional distillation
Oxides of nitrogen are also produced during the combustion of paraffin in air.
Explain how these oxides of nitrogen are formed.
Nitrogen and oxygen (from air) react
at high temperatures
Give the general formula for the homologous series that contains dodecane.
CnH2n+2
Write an equation for the cracking of one molecule of dodecane into equal amounts of two different molecules each containing the same number of carbon atoms.
State the empirical formula of the straight-chain alkane that is formed.
Name the catalyst used in this reaction.
C12H26 –> C6H14 + C6H12
C3H7
Zeolite
Explain why the melting point of dodecane is higher than the melting point of the straight-chain alkane produced by cracking dodecane.
Larger molecule
More van der Waals’ forces between molecules
Dodecane can be converted into halododecanes.
Deduce the formula of a substance that could be reacted with dodecane to produce 1-chlorododecane and hydrogen chloride only.
Cl2
Thallium(I) bromide (TlBr) is a crystalline solid with a melting point of 480 ºC.
Suggest the type of bonding present in thallium(I) bromide and state why the melting
point is high.
Ionic
Oppositely charged ions / Tl + and Br– ions
Strong attraction between ions
Identify which one of the isotopes of X is deflected the most in the magnetic field of a mass spectrometer. Give a reason for your answer.
number
Lowest mass / lowest m/z
Explain how the current in a mass spectrometer is generated.
Electron(s) transferred / flow (at the detector)
(From detector / plate) to the (+) ion
State one hazard associated with carbon.
causes global dimming
Other than cracking, give one common use of Y.
Jet fuel
Identify a catalyst used in a catalytic converter and why other than cost it is used.
platinum
it can withstand high temperatures
Deduce the type of crystal structure shown by graphane.
macromolecular
State how two carbon atoms form a carbon–carbon bond in graphane.
bond due to the shared pair of electrons
Deduce the empirical formula of graphane.
CH
Phosphine (PH3) has a structure similar to ammonia.
In terms of intermolecular forces, suggest the main reason why phosphine is almost insoluble in water.
(Phosphine) does not form hydrogen bonds (with water)
An aluminium chloride molecule reacts with a chloride ion to form the AlCl4− ion.
Name the type of bond formed in this reaction. Explain how this type of bond is formed in the AlCl4− ion.
Coordinate / dative (covalent)
Electron pair on Cl– donated to Al(Cl3)
Aluminium chloride has a relative molecular mass of 267 in the gas phase.
Deduce the formula of the aluminium compound that has a relative molecular mass of 267.
Al2Cl6
Deduce the name or formula of a compound that has the same number of atoms, the
same number of electrons and the same shape as the AlCl4− ion.
SiCl4
Explain why the TlCl2+ ion has the shape that you have drawn .
(electrons in) the bonds repel to be as far apart as possible
Which one of the first, second or third ionisations of thallium produces an ion with the electron configuration [Xe] 5d106s1?
Second
Identify the Period 2 element, from carbon to fluorine, that has the largest atomic radius. Explain your answer.
Carbon / C
smallest nuclear charge
Similar shielding
State the general trend in first ionisation energies from carbon to neon.
Deduce the element that deviates from this trend and explain why this element deviates from the trend.
Increase
Oxygen / O
Paired electrons in a (2)p orbital
(Paired electrons in a p orbital) repel
Deduce the element in Period 2, from lithium to neon, that has the highest second ionisation energy.
Lithium
Predict the type of crystal structure in solid zinc fluoride and explain why its melting point is high.
Ionic Strong (electrostatic) attraction (between ions) between oppositely charged ions / + and – ions / F– and Zn2+ ions
Give the general formula of the homologous series of straight-chain bromoalkanes that contains one bromine atom per molecule
CnH2n+1Br
Suggest one reason why 1-bromohexane has a higher boiling point than Z.
Stronger / more vdw (forces) between molecules
State the meaning of the term mass number of an isotope.
(Total number of) protons and neutrons (in nucleus of
atom)
In a mass spectrometer, the isotopes of an element are separated.
Two measurements for each isotope are recorded on the mass spectrum.
State the two measurements that are recorded for each isotope.
m/z
(relative) abundance
Give one reason why the second ionisation energy of silicon is lower than the second ionisation energy of aluminium.
electron in silicon is more shielded
Predict the element in Period 3 that has the highest second ionisation energy.
Give a reason for your answer.
Sodium / Na
Electron (removed) from the 2nd shell / 2p (orbital)
The following table gives the successive ionisation energies of an element in Period 3.
Identify this element.
Silicon
Explain why the ionisation energy of every element is endothermic.
energy is needed to overcome the attraction between
the (negative) electron and the (positive) nucleus or
protons
Suggest why the electronegativity of the elements increases from lithium to fluorine
bigger nuclear charge
similar shielding
State the type of bonding in lithium fluoride.
Explain why a lot of energy is needed to melt a sample of solid lithium fluoride.
Ionic Strong (electrostatic) attractions between oppositely charged Li+ and F- ions
Deduce why the bonding in nitrogen oxide is covalent rather than ionic.
Small electronegativity difference / they are both non-metal
Suggest the type of crystal shown by OF2
(simple) molecular
Both C3H8 and C4H10 can be liquefied and used as fuels for camping stoves.
Suggest, with a reason, which of these two fuels is liquefied more easily.
C4H10
because it is a larger molecule
Explain why the complete combustion of C4H10 may contribute to environmental problems.
CO2 produced is a greenhouse gas and contributes to global warming
Identify a compound that is used to react with the sulfur dioxide in the products of
combustion before they enter the atmosphere.
Give one reason why this compound reacts with sulfur dioxide.
calcium carbonate
Neutralises the SO2
Ethanethiol and ethanol molecules have similar shapes.
Explain why ethanol has the higher boiling point.
because Ethanol contains Hydrogen bonding
Which is stronger than van der waals in ethanethiol
Suggest why a leak of NO2 gas from the Ostwald Process will cause atmospheric pollution.
NO2 contributes to acid rain
Give one reason why excess air is used in the Ostwald Process.
ensure complete combustion takes place
Ammonia reacts with nitric acid as shown in this equation.
NH3 + HNO3 → NH4NO3
Deduce the type of reaction occurring.
Neutralisation
Explain why the AsCl4+ ion has a bond angle of 109.5º
There are 4 pairs of electrons
and the electron pairs repel equally
Explain how the gaseous atoms of rubidium are ionised in a mass spectrometer.
Electron gun
Knock out electron(s)
State one reason why the first ionisation energy of rubidium is lower than the first ionisation energy of sodium.
more shells in Rb so there is more shielding in Rb
By reference to the relevant part of the mass spectrometer, explain how the abundance
of an isotope in a sample of rubidium is determined.
Detector
detects the flow of electron as an electric current
Predict whether an atom of 88Sr will have an atomic radius that is larger than, smaller than or the same as the atomic radius of 87Rb. Explain your answer
Smaller
Bigger nuclear charge / more protons in Sr
Similar/same shielding
State why high temperatures are needed for thermal cracking.
Break (C-C or C-H) bonds
Suggest the formula of a reagent that could be added to alkenes in order to convert it into alkanes.
H2
Explain why the boiling points of alkenes and alkanes are similar
(Molecules) are similar sizes
so have similar intermolecular forces
Although phosphine molecules contain hydrogen atoms, there is no hydrogen bonding between phosphine molecules.
Suggest an explanation for this.
Difference in electronegativity between P and H is too
small
Suggest why graphene is an excellent conductor of electricity
Delocalised electrons / free electrons
Able to move / flow (through the crystal)
Explain, in terms of its structure and bonding, why titanium has a high melting point.
Nucleus / protons / positive ions and delocalised
electrons (are attracted)
Strong attraction
Explain why boron trichloride has a trigonal planar shape with equal bond angles.
3 bonds
Pairs repel equally
State the type of bond between Br and F in BrF3 and state how this bond is formed.
Covalent
Shared pair of electrons
The boiling points of fluorine and hydrogen fluoride are –188 oC and 19.5 oC respectively.
Explain, in terms of bonding, why the boiling point of fluorine is very low.
van der Waals forces between molecules
IMF are weak
Identify, from the Period 2 elements lithium to nitrogen, the element that has the largest
atomic radius.
Lithium
State the general trend in first ionisation energies for the Period 2 elements lithium to nitrogen.
Increase / gets bigger
Identify the element that deviates from this general trend, from lithium to nitrogen, and explain your answer.
Boron / B
Electron removed from (2)p orbital
Which is higher in energy
Identify the Period 2 element that has the following successive ionisation energies.
Carbon
Explain, in terms of structure and bonding, why the melting point of carbon is high.
Macromolecular / giant molecular / giant atomic
Covalent bonds in the structure
Strong (covalent) bonds must be broken or overcome /
(covalent) bonds need a lot of energy to break
C6H14 has structural isomers.
Deduce the number of structural isomers with molecular formula C6H14.
5
State one type of structural isomerism shown by the isomers of C6H14.
Chain (isomerism)
An element forms an ion Q with a single negative charge that has the same electron
configuration as the nitride ion.
Identify the ion Q.
Fluoride
Use the Periodic Table and your knowledge of electron arrangement to write the formula of lithium nitride.
Li3N
Suggest one reason why the yield of nitrogen dioxide formed during this reaction is often less than expected.
some (NO2) escapes
Suggest one reason why it is difficult to obtain a pure sample of nitrogen dioxide from this reaction.
hard to separate the 2 gases
State how krypton is ionised in the mass spectrometer. Sometimes the mass spectrum of Kr has a very small peak with an m/z value of 42
Explain the occurrence of this peak.
(Beam of electrons from) an electron gun
Knocks out electron(s
The 84Kr isotope
Has 2 electrons knocked out
Suggest one reason why particles with the same mass and velocity can be deflected
by different amounts in the same magnetic field.
different charges
Explain how the detector in a mass spectrometer enables the abundance of an isotope to be measured.
(ions hit detector and) cause current/(ions)
current proportional to abundance of the isotope
State the type of reaction that occurs when calcium carbonate reacts with nitric acid.
Neutralisation
State the type of bond formed between the N atom and the B atom in F2HNBF3.
Explain how this bond is formed.
dative covalent
Lone pair on N(HF2) donated (to BF3)
Suggest why the melting point of sodium iodide is lower than the melting point of sodium bromide.
Iodide is a bigger ion
Suggest why the first ionisation energy of krypton is lower than the first ionisation energy of argon.
Kr is a bigger atom
Deduce the group in the Periodic Table that contains this element.
2
With reference to the structure shown above give one reason why ice is less dense than water.
H2O molecules (in ice) are more spread out
State the strongest type of intermolecular force in methane.
Van der waals
Identify one molecule with the same number of atoms, the same number of electrons and the same shape as the H3O+ ion.
ammonia
State why more than the minimum energy is not used to ionise the sample of indium.
so only one electron is knocked out
Give two reasons why the sample of indium must be ionised.
so that the ions can be:
Accelerated
Deflect
Suggest one possible danger when a metal carbonate is reacted with an acid in a sealed flask.
may explode
State the type of structure shown by crystals of sulfur and phosphorus.
Explain why the melting point of sulfur is higher than the melting point of phosphorus.
(Simple) molecular
S bigger molecule (than P)
So more/ stronger van der Waals‟ forces (to be broken or overcome)
Explain why the melting point of aluminium is higher than the melting point of sodium.
Al has a bigger charge
More free /delocalised electrons
Stronger metallic bonding
State two characteristics of a homologous series.
Same) General formula /
Chemically similar
Suggest the strongest type of intermolecular force between CCI2F2 molecules.
dipole-dipole
Name the type of bond formed when a molecule of BF3 reacts with an F– ion. Explain how this bond is formed.
Coordinate/ dative (covalent)
(Lone) pair of electrons/ both electrons (on F-)
Donated from F / fluoride or donated to the BF3
State the bond angle in the BF4– ion.
109.5
Explain why the value of the first ionisation energy of sulfur is less than the value of the first ionisation energy of phosphorus.
Paired electrons in (3)p orbital
repel
State the trend in first ionisation energies in Group 2 from beryllium to barium.
Explain your answer in terms of a suitable model of atomic structure.
Decreases
Atomic radius increases/ electron removed further
from nucleus or nuclear charge/ electron in higher
energy level/ Atoms get larger/ more shells
As group is descended more shielding
State the type of crystal structure for each of iodine and graphite.
Iodine- molecular
Graphite- giant covalent
State the meaning of the term first ionisation energy.
Energy (needed) to remove one mole of electrons from one mole of atoms in the gaseous state.
A general trend exists in the first ionisation energies of the Period 2 elements lithium to fluorine. Identify one element which deviates from this general trend.
Oxygen
The first ionisation energy of aluminium is less than the first ionisation energy of magnesium.
The outer electron in Rb is in a 5s orbital (or next outer shell)
It is more shielded from the nucleus than outer electrons in Kr
The first ionisation energy of krypton is greater than that of bromine.
Krypton has more protons than bromine
But its outer electrons are in the same shell (or have similar shielding)
Give two reasons why this reaction might not be suitable for the removal of carbon dioxide from the exhaust gases of an engine.
reaction might be too slow
would need continuous supply of solution
The sodium hydroxide solution for this reaction can be made on an industrial scale, together with chlorine gas and hydrogen gas, by electrolysis of a dilute solution of sodium chloride. Suggest one commercial advantage and one environmental disadvantage of this industrial process.
commercial advantage could sell chlorine and/or hydrogen
environmental disadvantage generation of electricity likely to lead to release of CO2
In terms of atomic structure, explain why the van der Waals’ forces in liquid argon are very weak.
Argon particles are single atoms with electrons closer to nucleus
Cannot easily be polarised
