OCR A Level Chemistry Paper 1 - Periodic table, elements and physical chemistry

OCR A Level Chemistry Paper 1 - Periodic table, elements and physical chemistry Definition for rate of reaction - correct answearsthe change in concentration of a reactant or product per unit of time Definitio n of a covalent bond - correct answearsthe strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms Definition of an ionic bond - correct answearsthe electrostatic attraction between 2 oppositely charged ions Definition of an isomer - correct answearsatoms with the same number of protons but different numbers of neutrons Definition of an orbital - correct answearsa region of space that can hold up to two electrons of opposite spin Definition of electronegativ ity: - correct answearsthe ability of an atom to attract the pair of electrons in a covalent bond to itself Definition of relative atomic mass - correct answearsthe weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom of c arbon -12 Does reactivity increase or decrease down group 2 and why - correct answearsincreases because ionisation energies decrease due to the increasing atomic radius and increased shielding Does solubility increase or decrease down group 2 - correct an swearsincrease Equation to calculate the rate constant for first order reactions - correct answearsk=ln2÷t ₁/₂ Give the reaction for a group 2 element and a dilute acid - correct answearsM + 2HCl = MCl2 + H2 Give the reaction for a group 2 element and ox ygen - correct answears2M + O2 = 2MO Give the reaction for a group 2 element and water - correct answearsM + 2H2O = M(OH)2 + H2 How do you calculate molality and what is molality measured in? - correct answearsmolality = molarity x molar mass molality is measured in gdm ⁻³ How do you calculate the relative atomic mass of an isotope? - correct answears(isotope mass x percentage) + (isotope mass x percentage) ÷ 100 How do you convert absorbance to concentration - correct answearsuse a calibration curve How do you use a colorimeter (3 steps) - correct answears1. set the colorimeter to the wavelength of light you will be measuring 2. fill a cuvette with distilled water to calibrate the colorimeter. Set the absorbance to 0. 3. carry out the reaction, taking samples from the reaction mixture at regular intervals and measure the absorbance of each sample How does cis -platin work - correct answearsthe chloride ions are easily displaced so the complex bonds to two nitrogen atoms on the DNA molecule, preventing the cell from reproducing How does half life change for the different orders - correct answearsfirst order, half life is equal second order, half life increases zero order; half life decreases How does having a lone pair affect bond angle? - correct answearsLone pairs repel more than bonding pairs so for every lone pair take away 2.5° from the bond angle How does ionic charge affect lattice enthalpy - correct answearsthe higher the charge, the more energy is released when an ionic lattice forms due to stronger electrostatic forces between the ions so the higher the charge the more exothermic the lattice enthalpy. How does ionic radii affect lattice enthalpy - correct answearsthe smaller the atomic radii the more exothermi c the lattice enthalpy as the ions can sit closer together meaning that the attraction between the ions are stronger. How many electrons can one orbital hold? - correct answears2 How many orbitals are there in a d sub -shell? - correct answears5 How many orbitals are there in a p sub -shell? - correct answears3