Module 2 Flashcards
What is the relative mass of a proton? (1 mark)
1
What is the relative mass of a neutron? (1 mark)
1
What is the relative mass of an electron? (1 mark)
1/2000
What charge does a proton have? (1 mark)
1+
What charge does an electron have? (1 mark)
1-
What charge does a neutron have? (1 mark)
0
Why is an atom neutral? (2 marks)
There are the same number of protons and electrons,
so the charges cancel out.
What identifies an element, makes all the atoms of that element the same element? (1 mark)
The atomic number, aka the number of protons
State two differences in chemical properties between water and heavy water. (2 marks)
Heavy water has:
Higher melting and boiling points
Higher density
What is heavy water? (1 mark)
A form of water with an isotope of H in it (known as deuterium, 2,1H).
What is an isotope? (2 marks)
Atoms of an element with different numbers of neutrons, but the same number of protons.
What is an ion? (2 marks)
An ion is a charged atom.
It has a different number of protons from electrons.
Define relative isotopic mass. (2 marks)
Relative isotopic mass is the mass of an isotope relative to 1/12th of the mass of a carbon-12 atom.
Define relative atomic mass. (3 marks)
Relative atomic mass is the weighted mean mass of an atom relative to 1/12th of the mass of a carbon-12 atom.
How is the relative atomic/isotopic mass determined? (1 mark)
Using a mass spectrometer.
What ions to metals form? (1 mark)
Positive ions/cations
What ions do non-metals form? (1 mark)
Negative ions/anions
What is a binary compound? (1 mark)
A compound that only contains two elements.
What is a polyatomic ion? (1 mark)
An ion that contains atoms of more than one element bonded together.
What is the overall charge of an ionic compound? (1 mark)
0
Explain Avagadro’s constant. (1 mark)
The number of particles contained in one mole of any substance.
How do you calculate the number of moles something? (1 mark)
moles= mass/Mr or molar mass
What is molar mass? (1 mark)
The mass (in grams) in each mole of a substance.
What is a molecular formula? (1 mark)
The number of atoms of each element in a molecule.
What is an empirical formula? (1 mark)
The simplest whole number ratio of atoms of each element in a compound.
Define relative molecular mass (Mr). (2 marks)
Relative molecular mass is the mass of a molecule relative to 1/12th of the mass of a carbon-12 atom.
Define relative formula mass. (2 marks)
Relative formula mass is the mass of a formula unit relative to 1/12th of the mass of a carbon-12 atom.
What does it mean if a salt is hydrated? (1 mark)
Water molecules are part of their crystalline structure.
What are two assumptions that decrease the accuracy of experimental formula of hydrated salts? (2 marks)
All the water has been lost
No further decomposition of the salt
What are the two equations for concentration?
conc= mol/vol
conc=mass/vol
What is a standard solution? (1 mark)
A solution of known concentration.
What is molar gas volume? (2 marks)
The volume that a mole of gas molecules occupies, at a stated temperature and pressure.
State the ideal gas equation. (2 marks)
pV=nRT
What are the units for the ideal gas equation? (3 marks)
p- Pascals (Pa)
V- Metres cubed (m3)
n- Moles (mol)
R- 8.31 Jmol-1K-1 (the ideal gas constant)
T- Kelvin (K)
What are the values of room temperature and pressure (RTP)? (2 marks)
293K/298K or 20/25 degrees celcius
101kPa or 1atm
Explain what the term stoichiometry means. (1 mark)
The ratio of the amount, in mol, of each substance in an equation.
What is the equation for percentage yield? (1 mark)
= (actual yield/theoretical yield) x 100
What is the limiting reagent? (1 mark)
Th reactant that is not in excess.
What is the equation for atom economy? (1 mark)
= (Mr of desired products/Mr if all products) x 100
How is relative formula mass calculated? (1 mark)
By adding together the relative atomic masses of the elements in the empirical formula.
How do you convert between mol/vol and mass/vol? (1 mark)
mol/vol= (mass/vol)/Mr
Identify a compound of calcium that could be used to convert a soil pH from 5.8 to 7.5. (1 mark)
Ca(OH)2
or CaO
A salt has empirical formula H4N2O3, suggest the formulae of the ions present in this salt. (2 marks)
NH4+
NO3-
What element do all acids contain? (1 mark)
Hydrogen
What does an acid release when dissolved in water? (1 mark)
H+ ions
What is a strong acid? (2 marks)
A strong acid releases all its hydrogen atoms into solution as H+ ions
and completely dissociates in aqueous solution.
What is a weak acid? (2 marks)
A weak acid only releases a very small proportion of its available hydrogen atoms into solution as H+ ions.
A weak acid only partially dissociates.
Define the term ‘base’. (1 mark)
A base is a substance which readily accepts H+ ions.
What is an alkali? (2 marks)
An alkali is a base that dissolves in water
releasing OH- ions into the solution.
What does an alkali release when dissolved in water? (1 mark)
OH- ions
Describe what happens when an acid is neutralised. (2 marks)
The H+ ions from acid react with OH- ions from base to form a salt and neutral water.
What is formed when an acid reacts with a metal hydroxide? (2 marks)
Water and a salt
What is formed when an acid reacts with a metal oxide? (2 marks)
Water and a salt
What are formed when an acid and alkali react? (2 marks)
Water and a salt
What are formed when an acid and metal carbonate react? (2 marks)
Water, carbon dioxide, and a salt
Explain the statement ‘Sulphuric acid is a strong acid, but this is true only for one of the two hydrogen atoms. (3 marks)
When sulphuric acid is mixed with water each H2SO4 molecule dissociates, releasing just one of its two hydrogen atoms as an H+ ion.
This means HSO4 - ions are formed, which behave as a weak acid.
Finish the sentence:
A burette reading is recorded to the nearest…. (1 mark)
Half division
What is a concordant result, in titration, and what are they used for? (2 marks)
Titres within 0.10cm3 of each other.
They are used to calculate the mean titre.
What is the oxidation number of an element? (1 mark)
0
Where is the sign placed for an oxidation number? (1 mark)
BEFORE the number
What is the oxidation number of hydrogen in metal hydroxides? (1 mark)
-1
e.g. NaH or CaH2
What is the oxidation number of oxygen in peroxides? (1 mark)
-1
e.g H2O2
What is the oxidation number of oxygen when bonded to fluorine? (1 mark)
+2
e.g. F2O
What is a redox reaction? (1 mark)
Redox reactions involve reduction and oxidation.
What is oxidation in terms of electrons? (1 mark)
The loss of electrons.
What is reduction, in terms of electrons? (1 mark)
The gain of electrons.
What is oxidation, in terms of oxygen? (1 mark)
Gain of oxygen.
What is reduction, in terms of oxygen? (1 mark)
Loss of oxygen.
What is oxidation, in terms of oxidation number? (1 mark)
Increase in oxidation number.
What is reduction, in terms of oxidation number? (1 mark)
Decrease in oxidation number.
What is the significance of oxidation number in equations? (1 mark)
The changes in oxidation number balance out in an equation.
What is the shell number called? (1 mark)
The principle quantum number (n)
When n is the number of the shell, what is the formula for the number of electrons in a shell? (1 mark)
2n^2
What are shells made up of? (1 mark)
Atomic orbitals
How many electrons does an atomic orbital hold, and what direction do they spin? (2 marks)
2
opposite directions
What are the types of atomic orbital? (4 marks)
s-orbitals
p-orbitals
d-orbitals
f-orbitals
How many s-orbitals are in a shell from n=1? (1 mark)
1
How many p-orbitals are in a shell from n=2? (1 mark)
3
How many d-orbitals are in a shell from n=3? (1 mark)
5
How many f-orbitals are in a shell from n=4? (1 mark)
7
How many electrons are in an s-orbital? (1 mark)
2
How many electrons are in a p-orbital? (1 mark)
6
How many electrons are in a d-orbital? (1 mark)
10
How many electrons are in a f-orbital? (1 mark)
14
How many electrons are in shell 1? (1 mark)
2
How many electrons are in shell 2? (1 mark)
2 + 6= 8
How many electrons are in shell 3? (1 mark)
2 + 6 + 10= 18
How many electrons are in shell 4? (1 mark)
2 + 6 + 10 + 14= 32
What order are orbitals filled in? (1 mark)
In order of increasing energy.
What is an electron orbital? (2 marks)
A region around the nucleus that can hold up to 2 electrons with opposite spins.
What are the two exceptions to the 3d, 4s rule? (2 marks)
Chromium
Copper
What is ionic bonding? (1 mark)
The electrostatic attraction between positive and negative ions.
What is the structure of ionic compounds? (1 mark)
Giant ionic lattice
Why do ionic compounds dissolve in water? (2 marks)
Water is polar, the polar water molecules break down the lattice and surround each ion in solution.
What is covalent bonding? (2 marks)
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
What is dative covalent bond? (1 mark)
A covalent bond in which the shared pair of electrons has been supplied by one of the bonding atoms only.
What is the correlation between bond enthalpy and bond strength? (1 mark)
The larger the value of the average bond enthalpy, the stronger the covalent bond.
What does isoelectronic mean? (1 mark)
Two molecules have the same number of electrons.
What shape is an s-orbital? (1 mark)
Spherical
What shape is a p-orbital? (1 mark)
Dumb-bell
Does a lone pair or bonded pair repel more strongly? (1 mark)
Lone pair
Why does a lone pair repel more strongly than a bonded pair? 2 marks)
A lone pair is slightly closer to the central atom, and occupies more space.
What is the bond angle decreased by for each lone pair? (1 mark)
2.5 degrees
What is the bond angle and shape of methane? (2 marks)
Tetrahedral
109.5
What is the bond angle of a tetrahedral molecule? (1 mark)
109.5
What is the shape of a molecule with bond angle 109.5?
Tetrahedral
What is the shape and bond angle of a molecule with 4 bonded pairs and no lone pairs? (2 marks)
Tetrahedral 109.5
What is the shape and bond angle of ammonia? (2 marks)
Pyramidal
107
What is the bond angle of a molecule with a pyramidal shape? (1 mark)
107
What is the shape of a molecule with bond angle 107? (1 mark)
Pyramidal
What is the shape and bond angle of a molecule with 2 bonded pairs and 2 lone pairs? (2 marks)
Non- linear
104.5
What is the shape of a molecule with bond angle 104.5? (1 mark)
Non-linear
What is the shape and bond angle of a molecule with three bonded paired and one lone pair? (2 marks)
Pyramidal
107
What is the bond angle of a molecule with a non-linear shape? (1 mark)
104.5
What is the shape and bond angle of water? (2 marks)
Non-linear
104.5
What is the shape of a molecule with 2 electron regions? (2 marks)
Linear
What is the bond angle of a linear molecule? (1 mark)
180
What is the bond angle and shape of carbon dioxide? (2 marks)
Linear
180
What is the shape of a molecule with bond angle 180? (1 mark)
Linear
What is the shape and bond angle of a molecule with 3 electron pairs/regions?
Trigonal planar
120
What is the shape of a molecule with bond angle 120? (1 mark)
Trigonal planar
What is the shape and bond angle of BF3? (2 marks)
Trigonal planar
120
What is the bond angle of a molecule with a trigonal planar shape? (1 mark)
120
What is the bond angle and shape of sulphur hexafluoride? (2 marks)
Octahedral
90
What is the bond angle of a molecule with an octahedral shape? (1 mark)
90
What is the bond angle and shape of a molecule with 6 electron pairs/regions? (2 marks)
90
Octahedral
What is the shape of a molecule with bond angle 90? (1 mark)
Octahedral
What is electronegativity? (1 mark)
The attraction of a bonded atom for the pair of electrons in a covalent bond.
How is electronegativity measured? (1 mark)
The Pauling scale
Describe electronegative on the periodic table. (2 marks)
The top right of the periodic table contains the most electronegative elements. With Florine being in the corner (ignore group 0).
Is an ionic or covalent bond more electronegative? (1 mark)
Ionic
What does a bond being non-polar mean? (1 mark)
The bonded electron pair is shared equally between the bonded atoms.
What does it mean when a bond is described as polar? (1 mark)
The bonded electron pair is shared unequally between the bonded atoms.
Why is carbon dioxide non-polar even though it contains two C=O bonds with permanent dipoles? (1 mark)
The two dipoles act I’m opposite directions and exactly oppose each other (due to a linear shape).
What are the three main catagories of intermolecular forces? (3 marks)
Induced dipole-dipole interactions
Permanent dipole-dipole interactions
Hydrogen bonding
Which intermolecular force is the strongest? (1 mark)
Hydrogen bond
Which intermolecular bond is the weakest? (1 mark)
Induced dipole-dipole interactions
Where are induced dipole-dipole interactions? (2 marks)
Exist between all molecules.
They act between induced dipoles in different molecules.
Describe the origin of induced dipole-dipole interactions. (3 marks)
Movement of electrons produces a changing dipole in a molecule.
At any instant, an instantaneous dipole will exist (position is alway shifting).
This instantaneous dipole induces a dipole on a neighbouring molecule.
Etc.
Describe the strength of the induced dipole-dipole interactions in a molecule with more electrons. (3 marks)
Larger instantaneous and induced dipoles
Greater the induced dipole-dipole interactions
The stronger the attractive forces between molecules.
Where are permanent dipole-dipole interactions? (2 marks)
They act between the permanent dipoles in different polar molecules.
Describe the bonding and intermolecular forces in a simple molecular lattice. (2 marks)
Strong covalent bonds
Weak intermolecular forces.
What happened when a simple non-polar molecular substance is added to a non-polar solvent? (3 marks)
Intermolecular forces form between the molecules and the solvent.
The interactions weaken the intermolecular forces in the simple molecular lattice.
The intermolecular forces break.
The compound dissolves.
Why are non-polar simple molecular substances insoluble in polar solvents? (2 marks)
The intermolecular bonding within the polar solvent is too strong to be broken, so there is little interaction between the molecules keep s in the lattice and the solevent molecules.
What is the solubility of a polar simple molecular substance dependent on? (1 mark)
The strength of the dipole.
Describe the electrical conductivity of simple molecular structures. (2 marks)
There are no mobile charge carriers, so they do not conduct electricity.
What three elements can form a hydrogen bond with H? (3 marks)
Oxygen
Nitrogen
Fluorine
Why is ice less dense than water? (2 marks)
Hydrogen bonds hold water molecules apart in an open lattice structure in ice.
Why does water have a relatively high melting and boiling point? (2 marks)
Hydrogen bonds are really strong, require more energy to be broken.
What is the bond angle of a molecule with a square planar shape? (1 mark)
90 degrees
How many lone/bonded pairs of electrons does a molecule with a square planar shape have? (2 marks)
4 bonded
2 lone
Which elements form a square planar shape? (3 marks)
Au
Pt
Pd
