Curly arrows - Study guides, Revision notes & Summaries

AQA A-LEVEL CHEMISTRY 7405/2 PAPER 2 MARK SCHEME A-level CHEMISTRY 7405/2 Paper 2 Organic and Physical Chemistry Mark scheme Version: 1.0 Final *6A7405/2/MS* Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation events which all associates p...

3.2 Marking procedure for calculations Full marks should be awarded for a correct numerical answer, without any working shown, unless the question states ‘Show your working’ or ‘justify your answer’. In thiscase, the mark scheme will clearly indicate what is required to gain full credit. If an answer to a calculation is incorrect and working is shown, process mark(s) can usually be gained by correct substitution / working and this is shown in the ‘Comments’column or by each stage o...

MARK SCHEME – A-LEVEL CHEMISTRY – 7405/3 – JUNE 2021 9 3 3.14 Organic reaction mechanisms Curly arrows should originate either from a lone pair of electrons or from a bond. The following representations should not gain credit and will be penalised each time within a clip. H3C Br _ : H C . Br H3C . .Br .. _ OH OH For example, the following would score zero marks H H3C C Br HO H When the curly arrow is showing the formation of a bond to an atom, the arrow can go directly to...

MARK SCHEME – AS CHEMISTRY – 7404/2 – JUNE 2021 9 3 3.14 Organic reaction mechanisms Curly arrows should originate either from a lone pair of electrons or from a bond. The following representations should not gain credit and will be penalised each time within a clip. H3C Br _ : H C . Br H3C . .Br .. _ OH OH For example, the following would score zero marks. H H3C C Br HO H When the curly arrow is showing the formation of a bond to an atom, the arrow can go directly to the...

Diagrams of mechanisms in OCR A. Includes: electrophilic addition, electrophilic substitution, nucleophilic addition, nucleophilic substitution (as well as elimination and nucleophilic addition/elimination but this isn't in the spec.)

subsequent equation or observation) can be scored from an incorrect attempt (possibly an incomplete reagent) at the correct reagent. Specific details will be given in mark schemes. For example, no credit would be given for  the cyanide ion or CN– when the reagent should be potassium cyanide or KCN;  the hydroxide ion or OH– when the reagent should be sodium hydroxide or NaOH; MARK SCHEME – A-LEVEL CHEMISTRY – 7405/2 – JUNE 2021 6  the Ag(NH3)2+ ion when the reagent shoul...

MARK SCHEME – AS CHEMISTRY – 7404/1 – JUNE 2021 10  In most cases, the use of “sticks” to represent C ─ H bonds in a structure should not be penalised. The exceptions to this when “sticks” will be penalised include  structures in mechanisms where the C ─ H bond is essential (eg elimination reactions in halogenoalkanes and alcohols)  when a displayed formula is required  when a skeletal structure is required or has been drawn by the candidate 3.13 Organic names...

Following notes contain everything related to organic chemistry from CH106 course - Drawings - Mechanisms - Examples - Definitions