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Chem a level

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Sulfuric acid


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429 questions
Acid + metal =
Salt + hydrogen
Acdid + metal carbonate
Salt + water + c02
Cm moles=
C x v /1000
Cm v=
Nx1000 /c
Cm c=
N x10000/ v
Gases at rtp. moles=
Vx24000 or v x 24 (DM)
Gases at rtp volume=
N/24000 or n/24
Pressure. killer pascal into pascals
You divide by 1000/ 10-3
Volume is measured in m3 so
Dm -m divide by 10-3 cm-m divide by 10-6
No of particles
N x 6.02 x 10-23
Finding a relative molecular mass in gass eq
1. Conversions out what you know 3. figure out eq ( pv=nrt) or (n=vx24000 or 24) 4. work out your moles for the eq mr= m/n
The ratio of the balanced equation
Reacting masses
1. work out the moles of the info provided 2. check the stoichiometry ratio to see if it needs x or / 3. then put in m=nxmr or different for gas or conc
Unknown metal
1. work out moles 2. check stoich 3. work out moles/ mass = mr 4. periodic table
Percentage yield
Actual yield/ theoretical yield x 100 1. work out the moles of both depending on the question may have to work backwards
Atom Economy
Sum of molar mass of desired / sum of molar mass of all products x 100 x + x = h + co2 h/ co2 + h for substainability
Strong acid
H+ ions completely dissoaciates
Weak acids
Partially dissociates
Proton acceptor
Proton donor
Ionic equations
Solids- don’t split Liquids - don’t split Gases don’t split Aqueous split
Standard solution in buriet
Divide by mean titre
Mean tire
Put 23.0
./. Uncertainty
Uncertainty/ volume measured x 100
Moles =
Mr x moles
Empirical formulae
The simpler ratio
Molecular formula
Actual ratio
Water crystallisation
C-a= Anhydrous B-C=Water
The definition of an Atomic orbital is
Shells are made up of atomic orbitals. An atomic orbital is the region around the nucleus that can hold up two electrons with opposite spins.
S orbital
S= sphere each shell contains 1s orbital 1st shell contains only s ( 1s1 1s2)
P orbitals
Shape = dumb bell each shell from the 2nd contains 3p orbitals with 2 electrons in each so in tot 6 e ( 1s22s22p6)
Shell 3
Consist of p and s orbitals with a higher energy level
D orbitals
- 5 d orbitals so 10 electrons
When it gets to the 4th shell they is
... backfilling by the 3d block due to 3d having higher energy than 4s subshell
Electron pairing occurs when
Two electrons are in opposite spin as they are both negatively charged to counteract repulsion
Short hand configuration
The last electron from group 8 goes in square brackets [ne]1s2
Orbital =
2 electrons
N=4 shell
They are 4 sub shells s,p,f,d so 2+6+10+14 =32
Definition of ionic bonding
Electrostatic attraction between oppositely charged ions
Things to remember in dot and cross diagrams
- square brackets [] - can put a big 2 or n number infront of brackets - remember the charges on the outside of []
Structure of an ionic compound
Each ion attracts oppositely charged ions in all directions resulting in a giant ionic lattice.
Properties of ionic compound
-solid at rtp due to insufficient energy to overcome the strong electrostatic forces of attraction between oppositely charged ion . so high temp needed so HIGH MELTING AND BOILING POINT -soluble in polar solvents (charged) - Electric conductivity inn liquid state as ions are delocalised and free to move as charge carriers
Definition of covalent bonding
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atom
A covalent bond is localised due to
The attraction solely between the shared pair of electrons and nuclei of the two bonded atoms
A rule in covalent bonding diagrams
A central atom doesn't have to have 8 electrons
The nitrogen bonding is what type
Dative covalent bonds
When the shared pair of electrons comes from the one/same element
Electron pair repulsion theory states
Negative charge - repulsion The electrons surrounding the central atom determine the shape of the molecules. As they repel they are arranged as far apart as possible so the arrangement lowers repulsion
4bonding regions 109.5 degrees
3 bonding regions 1 lone pair 107 degrees
Non linear
2 bonding regions 2 lone pairs 104.5 degrees
2 bonding region 180 degrees
Triagonal planar
3 bonding regions 120 degrees
6 bonding regions 90 degrees
Electronegativity definition
The attraction of a bonded atom for the pair of electron in a covalent bond
Factors affecting electroegatvity
- The nuclear charges are different - The atoms may be different sizes -The shared pair of electrons may be closer to nucleus than the other
Non polar bonds terms
Bonded atoms are the same or same or siimiliar electronegativity
Delta + and delta - are given
Larger e neg gets delta - smaller e neg gets delta +
Which molecules have an overall dipole
Non-symmetrical molecules so polar molecules have a dipole overall eg. pyramidal and non linear
Polar covalent bond definition
Shared paired of electrons where the electron is not shared equally so e neg difference
Dipole definition
Charged separation across a bond with one atom having a delta + charge and one item with delta - charge
IMF definition
Weak interactions between dipoles of a different molecules
Types of IMF
Induced dipole-dipole (LONDON) permanent dipole-dipole Hydrogen bonding
What are IMF responsible for
Melting and boiling ptts and density
London forces...
... Electrons move causing uneven distribution ... a tempory instantaneous dipole is set up in one molecule... induces a temp dipole in adjacent molecule hence the attraction
Permanent dipole-dipole interactions
-asymmetrical -polar -forever
Simple Molecular substance is
Small units containing a definte number of atoms
Properties of simple MS
-low melting and boiling point due to weak intermolecular forces -covalent bonds do not break -soluble in non polar soluvents - hexane -non conductors of electricity - fixed p and no charged carriers
Why don't Simple MS dissolve in water
Little interaction between the molecules in the lattice and the polar solvent molecules
Hydrogen bonding
The lone pair on the electronegative atom on one molecule and the electron deficient hydrogen on an adjacent molecule
Elements are arranged by the
Increasing atom number