Overview And Tips For A Level H2 Chemistry
H2 Chemistry at the A Levels emphasises the active application of scientific concepts and principles. At the O Levels, learning is not as deep, and the difficulty of questions lies at the surface level. Chemistry is often referred to as the central science because it joins together physics and mathematics, biology and medicine; it is important that we put in the effort to secure a good fundamental understanding of it! In the following article from the top Chemistry tuition center in Singapore, Zenith outlines the H2 syllabus and provides insights into its different themes!
Fig 1. Breakdown of H2 Chemistry mark allocation
From our JC Chemistry tuition’s breakdown of the H2 Chem syllabus outline (Fig.1), we see that Paper 3, Free-Response Questions, takes up the highest weighting at 35%. Next in line is Paper 2, Structured Questions, at 30%. Together, they constitute 65% of the total Chemistry grade, as long answer question types. That is almost ⅔ of the total weightage, a significant portion that students must take note of when prepping for the exams. The next ⅓ goes to Multiple Choice Questions, Paper 1 (15%) and the Practical, Paper 4 (20%). Sometimes, students underestimate the mark weightage of Paper 4, instead allocating more time to studying for Paper 1. That is a mistake you shouldn't make! It is also important to be familiar with the Practical aspect of H2 A Level Chemistry. Practical skills may imply that you have a real-world grasp of the theoretical aspects of the syllabus. This means enhancing your evaluation and problem-solving abilities!
Fig 2. H2 Chemistry Themes and Chapters
When we pick apart SEAB’s curriculum structure (Fig 2.), we see that the central overriding theme of H2 Chemistry is Matter. This corresponds to the chemical properties and structures of various atoms. Atoms are the most basic building block of life, and as such, the study of it is introduced in the syllabus under its own theme, Matter.
Following that, we have the second theme, Structure and Properties. This encompasses the chapters of Chemical Bonding, Gaseous States, the Theories of Acids and Bases, and the Periodic Table. These build on the study of Atomic Structure, where we now explore the relationships between molecules. In Chemical Bonding, the types of bonds and their properties are looked into at greater detail. In Gaseous States, we explore the definition of an Ideal Gas and learn how to apply the general gas equation: pV = nRT. In Acids & Bases, we learn to interpret three important laws - the Arrhenius, Brønsted-Lowry, and Lewis theories of Acids and Bases. And in the Periodic Table, we become more confident in categorizing trends and properties across Periods, or down a Group.
The next theme is organised around the Transformation of Matter. This involves the study of the feasibility and rate of reactions. The first chapter of this theme is the Mole Concept and Stoichiometry, where you will learn how to calculate the quantities of reactants. Following that is Chemical Energetics/Thermodynamics, where you will figure out how to quantify the energy changes of reaction pathways. In Reaction Kinetics, the rates of reactions are examined, while in Chemical Equilibria, a more in-depth exploration of reversible reactions and dynamic equilibria is considered.
The above three themes are classified as Core Ideas. As the top Chemistry tuition center in Singapore, Zenith recognises that a keen grasp of these topics is fundamental in doing well for the Extension Topics, which are made up with: Chemistry of Aqueous Solutions, Electrochemistry, Chemistry of the Transition Elements, and Organic Chemistry. In these Extension Topics, we explore and expound on content taught from the Core Ideas. For example, in the Chemistry of Aqueous Solutions, the previously mentioned topics of Acids and Bases and Chemical Equilibria provide the basis for its mastery. Likewise, in Transition Elements, you are required to work very closely with the chapter on the Periodic Table. That is why these topics are classified as “extensions”- the knowledge learnt in the Core Ideas helps supplement the content that falls under their umbrellas.
Tips and Insights
Theme 1 (Matter): Revise and Re-learn
Zenith’s JC Chemistry tuition programme recommends that for the first theme, Matter, you adopt a mindset of re-learning. In other words, that means preparing yourself to be introduced to entirely new concepts and ideas that may shake your way of thinking. Re-learning entails constant revision and evaluation of the knowledge stored in our heads; eminent scientists across history have adopted this strategy to make new discoveries! In the context of H2 Chemistry, this can be applied too. At the start of your JC Chemistry journey, you will find that the content being taught upends many previously held notions of Chemistry from the O Level syllabus. For example, at the O Levels, on Atomic Structure, it is imprinted in your mind that an atomic shell is full at 8 valence electrons. However, in the JC H2 syllabus, students have to come to the realisation that atoms can have more than 8 valence electrons, with that number possibly reaching 18! On top of that, certain atoms may not only have electron shells but also subshells and orbitals (Fig 3.). At this stage, it is important that you revise and reevaluate certain concepts and theorems learnt in secondary school. You should not entirely disregard all that you have learnt, for some snippets are relevant, as the A Levels build upon past knowledge from your secondary education. Often, the concepts learnt previously are simplified into easier chunks of information. At the A Levels, these are greatly expounded on and taught in greater detail.
Fig 3. Atomic Structure: d-orbitals
Theme 2 (Structure and Properties): Observe Trends!
At the best Chemistry tuition in Singapore, Zenith’s tip for this theme is to familiarise yourself with the trends of the Chemistry syllabus. In particular, you should be able to identify and account for changes in bond energies, properties, and ionisation values. Over here, you need to be cognisant of the structures of molecules, solutions, and gases. That means a deep understanding of bonding abilities at an atomic level to a substance level.
Fig 4. A bonding and structure question at the A Levels
Very often, H2 Chemistry questions on bonding and structure are intertwined with other chapters. It is difficult for them to come in the form of a standalone question of say, 20 full marks, but it can be slotted into a variety of question types. For example, in Fig 4, we see bonding being asked of in the context of Organic Chemistry. It is important here that you fully understand the order and range of reactivity of atoms and ions. In this case, zwitterions, which contain a net positive charge, retain stronger forces of attraction as ionic bonds, than hydroxyethanoic acid, which is bounded together by weak intermolecular bonds as simple covalent molecules. Nevertheless, remember to familiarize yourself with trends, noting the combination of topics that may come up in different question variations.
Theme 3 (Transformation): Calculations defined by feasibility and rate
At the top Chemistry tuition center in Singapore, Zenith advises that for the chapters of Theme 3, it is key to understand that much of what you will be learning here is characterised by calculations. Specifically, calculations based on the possibility of reaction pathways, and the speed at which they occur. Of course, the foundational chapter which underpins all of this is Mole Stoichiometry, something that you will have been familiar with since secondary school! For the topic of Chemical Equilibria, much of what you learn in Reaction Kinetics and Thermodynamics will supplement your learning.
Fig 5. A Chemical Equilibria Question marrying Kinetics and Thermochemistry
From Fig 5, we see that being able to construct the Chemical expression as in part (i) requires knowledge in the chapter of Reaction Kinetics, with the concentration of products divided over the reactant’s concentrations. In part (iii), it is explained that the rate and yield of the reaction increase with an increase in temperature. This ties back to the chapter of Thermochemistry. In (ii), we observe how we are required to manipulate the concentrations of the reactants to derive the value of the equilibrium constant, Kc. This theme is ultimately grounded on calculations, whether it is to find the resultant energy change in an energy cycle diagram (as in Thermodynamics), to determine the rate constant in a first-order reaction, or to find the concentration of reactants at an equilibrium state in a gaseous system. In turn, these are all made possible by Mole Stoichiometry, which provides a solid base with which we quantify and formulate the necessary equilibria calculations with.
Theme 4 (Extension Topics)
Zenith’s JC Chemistry Tuition programme wishes to highlight how the Extension Topics tie back to the core topics of the H2 A Level Chemistry syllabus. In the topic of Chemistry of Aqueous Solutions, for example, much of whatever you will learn comes from Theme 2’s Theory of Acids and Bases, and Theme 3’s Chemical Equilibria. For the topic on Transition Elements, a strong grounding in Theme 2’s Periodic Table, coupled with good fundamental knowledge in Theme 1’s Atomic Structure (regarding the configuration of orbitals and electrons), is necessary if you want to have a good understanding of it. For Organic Chemistry and Electrochemistry, mastery of Theme 2’s Chemical Bonding is essential because it paves the way for explaining many organic compounds’ properties and reactions.
Since Organic Chemistry takes up such a significant portion of the extension topics' total grade allocation, Zenith, the best Chemistry tuition in Singapore has decided to shed some light on this topic in particular. Doing well in Organic Chemistry requires superb visualisation skills because you may be tasked to draw out the arrangements and shapes of Organic Compounds and Molecules. For Paper 3 of the H2 A Level Chemistry Paper, there often contains a Structural Elucidation Question on Organic Chemistry. Structural Elucidation refers to plotting out in detail the exact replica of the Organic Compound’s Molecular Formula, based on inferences of that compound's reactions with different reagents. After which, you will be required to explain in detail your reasoning behind your sketches: (Fig 6.)
Fig 6. A H2 A Level Organic Chemistry Structural Elucidation Question
From here, four separate structures are required to be drawn out in full detail. In other cases, you may be needed to construct a single but more complex organic molecule. It all depends on the demands of the question! Deductions are then made to support your drawings. From here, we see that a keen eye for observation is pivotal in constructing the accurate molecule.
Fig 7. An Organic Chemistry Reaction Mechanism question
Other times, your visualisation abilities may be put to the test in other question types. In Fig 7, we see a Reaction Mechanism requiring to be detailed in the drawing. Similar to Fig 6’s question, you will need to accurately sketch out the steps of the reaction based on the given parameters. These often come into play where Nucleophilic Addition and Nucleophilic Substitution reactions are concerned.
For the chapter on Chemical Equilibria and Transition Elements, visual ability is also a plus, but not in the area of diagram construction. In this circumstance, you will need to be aware of colour changes, in the form of pH changes as a result of titration, or as a result of a complex ion formation respectively. Also, because Paper 4’s content is largely derived from these extension topics, you will need to be on the ball visually during the hands-on portion of the H2 A Level Chemistry Examinations!
With all that, we hope that this guide has been of value to you! H2 Chemistry, considered by many to be a staple subject, finds its way into a myriad of JC Science stream subject combinations. At the tertiary level, Chemistry graduates (and their peers from related fields) remain highly sought after in today’s technologically driven world. As such, it is important to score in it!
At the top Chemistry tuition center in Singapore, we strive to ensure that all our students excel at the Chemistry A Level Examinations. Visit our testimonials page to find out more or jump straight to contacting us for a free trial today!