freestyle topics Flashcards
How has a salt been formed in this reaction?
A hydrogen ion (of an acid) has been replaced by a metal
ion
State what is meant by the term empirical formula.
The simplest whole number ratio of atoms (of each
element) present in a compound
Describe what is meant by the term ionic lattice, in terms of the type and arrangement of particles present.
Repeating pattern
of oppositely charged ions
What is meant by the term covalent bond ?
A shared pair of electrons.
Explain what is meant by the term electronegativity.
The ability of an atom to attract electrons
(Electron pair) in a (covalent) bond
Explain why a CH2Cl2 molecule is polar.
The dipoles do not cancel out
OR
Because the molecule is non-symmetrical
Calcium hydroxide is both a base and an alkali. Refer to any relevant ions in your answer.Explain what is meant by the terms base and alkali.
Base: A substance which readily accepts H+ ions (from an
acid)
Alkali: releases OH– ions into (aqueous) solution
A student prepares a solution of calcium nitrate from calcium carbonate.
What reagent would the student need to use?
Write the equation for the reaction.
Nitric acid OR HNO3
CaCO3 + 2HNO3 Ca(NO3)2 + H2O + CO2
What is meant by the term isotopes?
Atom(s) of an element
AND
with different numbers of neutrons (and with different
masses)
Different isotopes of antimony have the same chemical properties.Explain why
same number of electrons in outer shell
OR
same electron configuration OR electron structure
Define the term relative atomic mass.
The (weighted) mean mass of an atom (of an element)
OR
The (weighted) average mass of an atom (of an element)
compared with 1/12th (the mass)
of (one atom of) carbon-12
Predict the shape of a molecule of SbCl3.
(Trigonal) Pyramidal
(Sb has) three bonding pairs AND one lone pair of
electrons
Pairs of electrons repel
SbCl3 molecules are polar.Explain why.
There is a difference in electronegativities (between Sb and Cl) OR (Sb-Cl) bonds are polar OR have a dipole OR Dipoles seen on the diagram The molecule is not symmetrical AND dipoles do not cancel
A salt used as a fertiliser has the empirical formula H4N2O3.
Suggest the formulae of the ions present in this salt.
NH4
+ NO3
–
Suggest the formula of the acid used to prepare Ca3(PO4)2.
H3PO4
me a base which could be used to prepare Ca3(PO4)2.
Calcium oxide OR calcium hydroxide OR calcium
carbonate
State and explain two anomalous properties of ice caused by hydrogen bonding.
Property 1
Ice is less dense than water
Explanation 1
The molecules in ice are held apart by hydrogen bonds
OR
ice has an open lattice OR structure
Property 2
Ice has a relatively high melting point
Explanation 2
Hydrogen bonds are relatively strong
OR
Hydrogen bonds are stronger (than other intermolecular
attractions or forces)
OR
More energy is needed to overcome hydrogen bonding
Define the term relative isotopic mass.
Mass of the isotope compared to 1/12th
OR
mass of the atom compared to 1/12th
(the mass of an atom of) 12C
State the formulae of the two main ions present in the solution of Al2(SO4)3.
Al3+
SO4
2–
What does ‘•x H2O’ represent in the formula Al2(SO4)3•x H2O?
(The number of) water(s) of crystallisation
Why is Na3PO4 described as a salt of H3PO4?
The hydrogen ions OR H+ OR protons (of phosphoric
acid) are replaced by sodium ions OR Na+
Suggest why PH3 has a lower boiling point than NH3.
the intermolecular forces are weaker in PH3
What is a dative covalent bond?
Both electrons have been donated by one atom
) Define the term relative atomic mass.
The (weighted) mean mass of an atom (of an element)
OR
The (weighted) average mass of an atom (of an element)
compared with 1/12th (the mass)
of (one atom of) carbon-12
Describe how van der Waals’ forces arise.
Creating the dipole mark
Uneven distribution of electrons
Type of dipole mark
Creates or causes an instantaneous dipole OR temporary
dipole (in a molecule)
Induction of a second dipole mark
Causes induced dipoles in neighbouring molecules
Suggest why there are no other intermolecular forces in solid sulfur.
Only one type of atom
OR
No (permanent) dipoles OR non-polar OR no polar bonds
What does the term anhydrous mean?
There are no waters of crystallisation
Explain why a molecule of SF6 has an octahedral shape.
Sulfur has six bonded pairs (and no lone pairs)
Electron pairs repel (one another equally)
Explain what is meant by the term electronegativity and suggest why SF6 molecules are non-polar.
The ability of an atom to attract electrons
in a (covalent) bond
(The octahedral shape) is symmetrical
The systematic name for SrSO3 is strontium sulfate(IV).
Why does the number (IV) have to be used here rather than simply naming this compound as strontium sulfate?
It shows the oxidation number of the sulfur
OR
the name without the IV is ambiguous
Suggest the formula of the acid used to form SrSO3.
H2SO3
Give the formulae of the ions present in NH4Cl.
NH4+ AND Cl–
Apart from reasons of cost, suggest why some countries do not add KI to table salt.
Ethical implications
Some people feel it is wrong to put additives into the
national diet
OR
Dietary issues
Food OR diet contains sufficient amounts of iodide
At room temperature, chlorine is a gas and iodine is a solid. When heated together, chlorine reacts with iodine to form iodine monochloride, ICl.ICl has a higher boiling point than Cl 2.
Explain, in terms of the intermolecular forces present, why ICl has a higher boiling point than Cl 2.
Explanation 1
ICl has permanent dipole (–dipole) (interactions) AND
Cl2 has (only) van der Waals’ forces
Forces are stronger in ICl ORA
OR
More energy is needed to overcome forces in ICl
ORA
Explanation 2
ICl has more electrons ORA
Stronger van der Waals’ forces in ICl (than in Cl2) ORA
OR
More energy is needed to overcome van der Waals’
forces in ICl ORA
What is meant by the term hydrated calcium chloride?
Contains water (of crystallisation)
Explain what is meant by the term orbital.
A region (within an atom) that can hold (up to) two electrons (with opposite spin)
What is meant by one mole of substance?
(The amount of substance which contains) as many
particles as there are carbon atoms in 12g of 12C (atoms)
Explain why there is a difference in the melting points of K, KBr and H2O.In your answer you should refer to the types of particle, the types of forces between the particles and the relative strength of the forces between the particles in solid K, KBr and H2O.
Particle mark 1:
In K, (electrostatic attraction between)
positive ions/cations AND e– / electrons
Particle mark 2:
In KBr, (electrostatic attraction between) oppositely OR
positively AND negatively charged ions
Forces mark:
K has metallic bonding OR K has attraction between
positive ions and electrons
AND
KBr has ionic bonding OR KBr has attraction between
oppositely charged ions
In H2O,
Forces mark:
hydrogen bonding
Particles mark (QWC):
(Between) molecules
Order of strength of forces: KBr > K > H2O
OR
ionic bonding > metallic bonding > hydrogen bonding
Why can ammonium sulfate be described as a salt?
The H+ OR hydrogen ions OR protons in (sulfuric) acid
have been replaced by ammonium ions OR NH4+
Giant metallic lattices conduct electricity. Giant ionic lattices do not. If a giant ionic lattice is melted, the molten ionic compound will conduct electricity.
Explain these observations in terms of bonding, structure and particles present.
Metallic lattice has delocalised OR mobile electrons
OR metallic bonding has delocalised OR mobile electrons
Ionic lattice has no mobile ions
OR ionic solid has no mobile ions
molten ionic (compounds) have mobile ions
Suggest why ice has a higher melting point than solid ammonia.
Ice has stronger hydrogen bonds
O has two lone pairs (AND N has one)
OR
O more electronegative (than N)
Solid SiO2 melts at 2230 °C. Solid SiCl4 melts at –70 °C. Neither of the liquids formed conducts electricity.Suggest the type of lattice structure in solid SiO2 and in solid SiCl4 and explain the difference in melting points in terms of bonding and structure
SiO2 is giant covalent (lattice)
SiCl4 is simple molecular (lattice)
van der Waals’ forces in SiCl4
Covalent bonds broken in SiO2
Forces OR bonds are stronger in SiO2 (than in SiCl4)
OR more energy is needed to break forces OR bonds in SiO2
(than in SiCl4)
What 3-D shape is the 5s orbital?
Spherical OR sphere
What is meant by the term ionic bonding
(Electrostatic) attraction between oppositely charged
ions
Explain why a solution of copper(II) nitrate conducts electricity.
Ions are mobile OR ions can move
Molecules of BF3 contain polar bonds, but the molecules are non-polar.Suggest an explanation for this difference.
BF3 is symmetrical
The dipoles cancel out
State the formulae of two ions released when sulfuric acid is in aqueous solution.
Any two from
H+
SO42–
HSO4
A student adds a sample of solid potassium carbonate, K2CO3, to an excess of dilute sulfuric acid. Describe what the student would see and write the equation for the reaction which takes place.
Effervescence OR fizzing OR bubbling OR gas
produced
K2CO3 dissolves OR disappears OR colourless
solution is formed
H2SO4 + K2CO3 K2SO4 + CO2 + H2O
State the total number of electrons occupying the p orbitals in one chlorine atom.
11
) How many electrons are there in one ion of Ca2+?
18
Name the shape of, and state the bond angles in, a BF3 molecule. Explain why BF3 has this shape.
Shape: trigonal planar
Bond angle: 120°
Explanation:
Pairs of electrons repel (one another equally)
Boron has 3 bonded pairs (and 0 lone pairs)
Nitrogen can also form a fluoride, NF3, which has a permanent dipole. Explain why NF3 has a permanent dipole.
F is more electronegative than N OR -F–N+ Dipoles do not cancel OR NF3 is pyramidal (in words) / asymmetrical
In terms of protons, neutrons and electrons, how is an atom of 151Eu different from an atom of 153Eu?
In terms of protons, neutrons and electrons, how is an atom of 151Eu similar to an atom of 153Eu?
153Eu has (2) more neutrons
OR
153Eu has 90 neutrons AND 151Eu has 88 neutrons
(It has the) same number of protons AND electrons
OR
Both have 63 protons and 63 electrons
Write the equation for the reaction between dilute nitric acid and calcium hydroxide. Include state symbols.
2HNO3(aq) + Ca(OH)2(aq) → Ca(NO3)2(aq)+ 2H2O(l)
Formulae
Balance AND states
Explain how the hydroxide ion in aqueous calcium hydroxide acts as a base when it neutralises dilute nitric acid.
Accepts a proton OR accepts H+
What is meant by the term ionic bonding?
(Electrostatic) attraction between oppositely charged
ions.
Describe and explain one anomalous property of water which results from hydrogen bonding.
Liquid H2O is denser than solid
In solid state H2O molecules are held apart by
hydrogen bonds OR ice has an open lattice
OR
H2O has a relatively high boiling point OR melting
point
(relatively strong) hydrogen bonds need to be broken
OR a lot of energy is needed to overcome hydrogen
bonds OR hydrogen bonds are strong
Magnesium reacts with dilute acids. Describe what you would expect to see when magnesium ribbon is added to an excess of dilute hydrochloric acid.
Fizzes OR bubbles OR gas produced OR
effervescing
Mg dissolves OR Mg disappears OR a solution is
formed
Compare and explain the electrical conductivities of sodium and sodium oxide in the solid and liquid states.
sodium is a (good) conductor because it has mobile
electrons OR delocalised electrons
OR electrons can move
sodium oxide does not conduct as a solid
sodium oxide conducts when it is a liquid
ions cannot move in a solid
ions can move OR are mobile when liquid
Suggest why H2S has a much lower boiling point than H2O.
no hydrogen bonding
OR
weaker intermolecular forces
She noticed that when the ammonium chloride was solid it did not conduct electricity. However, when ammonium chloride was dissolved in water, the resulting solution did conduct electricity.Explain these observations.
ions OR electrons cannot move in a solid 9
ions can move OR are mobile in solution 9
