Chemistry - Section 2

Transcription

1 Chemistry - Section 2 BMAT Course Book BMAT Science Revision Mock Questions Step-by-Step Guides Detailed Explanations Page 1

2 Table of Contents Lesson Page Lesson 1: Introduction to BMAT Chemistry 3 Lesson 2: Atomic Structure 6 Lesson 3: Calculations - Reacting Masses 11 Lesson 4: Calculations - Percentage Yield 16 Lesson 5: Calculations - RMM, RFM, RAM 19 Lesson 6: Structure and Bonding 21 Lesson 7: Separation Techniques 25 Lesson 8: Balancing Equations* 28 Lesson 9: Reaction and Elements 29 Lesson 10: Chemistry - Extra Topics 30 Page 2

3 Introduction to BMAT Chemistry Lesson 1 Appreciate the various Chemistry topics tested in the BMAT, and the past trends from BMAT papers. Introduction to Section 2 Section 2 of the BMAT is based around GCSE level Biology, Chemistry, Physics and Maths. The content is GCSE-level, but they tend to ask difficult questions which stretch your GCSE knowledge to their extremes. In this section you get: Chemistry (6 to 8 questions) Physics (6 to 8 questions) Biology (6 to 8 questions) Maths (5 to 7 questions) How do I prepare for this section? Brush up on your GCSE knowledge. In this book we have covered the main topics, but it is worth reading the official BMAT Revision Guide on their website (free). It is similar to the CGP books, and goes through content in full detail. Don t revise everything GCSE. The BMAT specification tells you what you need to know. It is not the full GCSE specification, so don t waste time on irrelevant topics. Also, use our guides on the most testable topics to structure your revision and focus on the important topics first. Page 3

4 Introduction to BMAT Chemistry Lesson 1 Don t panic about Physics. Many BMAT students have not taken A-level Physics. Even if your Physics is rusty, don t stress. By going through our book, step by step, and supplementing it with extra revision guides, you will master the Physics section. Medic Mind Approach to Section 2 In this book each Section 2 subsection is broken down into 3 parts: 1. BMAT Specification - this is an extract from the official BMAT specification for Section 2. We extracted the points relevant to the particular tutorial. Most of the specification is covered in this book, but not all of it. We have focused on the most important and commonly tested elements of the specification. 2. Medic Mind Tips and Theory - in each tutorial we revise and summarise the key topics that come up. We have analysed all BMAT papers since 2009 (when the specification changed), to assess the most important topics. 3. Practice Questions - there are 1 to 5 practice questions per topic, found at the end of the tutorial. This should help you consolidate your learning by doing a BMAT style question (written by Medic Mind). How should I build on this course? After this course: Re-cap the BMAT specification and read the official BMAT free guide to fill gaps in your knowledge. Go through the specification and learn the science and maths content in full detail. We do not cover all topics in the specifications - this is a revision guide based on the most commonly tested topics. Therefore you should use the Official BMAT Revision Guide (found online) and the specification to supplement your learning here. Do the past papers using our compilations. On our website we have compiled every past paper question by topic ( These will be released on 1st October So, for example, after you learn Atomic Structure in this book, do the past paper questions on this same topic using our compilations. Page 4

5 Introduction to BMAT Chemistry Lesson 1 Commonly Tested Chemistry Topics The table below shows the frequency of the Chemistry topics which we will cover in this book. The BMAT Specification changed in 2009, so the figures are based on post 2009 BMAT Official Papers. Lesson Topic Number of Questions (since 2009*) 2 Atomic Structure 5 3 Calculations: Reacting Masses 7 4 Calculations: Percentage Yield 3 5 Calculations: RMM, RFM, RAM 5 6 Structure and Bonding 3 7 Separation Techniques 1 8 Balancing Equations* 6 9 Reactions & Elements* Chemistry: Extra Topics* - *Full tutorials can be found in the 2nd Edition of this Book, published on 1st October You can find this version on your Online Study Hub, along with tutorial videos for all lessons. Page 5

6 Atomic Structure Lesson 2 Understand the structure of an atom, including electron structure, mass number, atomic number and standard notation. BMAT Specification Describe the structure of the atom as a central nucleus (containing protons and neutrons) surrounded by electrons moving in shells/energy levels/orbits. Know the relative masses and charges of protons, neutrons and electrons and recognise that most of the mass of an atom is in the nucleus. Know that atomic number = number of protons. Know that mass number = number of protons + number of neutrons. Understand that in an atom the number of protons = the number of electrons so that atoms have no overall charge. Use the standard notation (e.g C) for any atom to calculate the number of protons, neutrons and electrons in an atom (and so any ion of the atom). Use the atomic number to write the electronic configurations of the first 20 elements in the Periodic Table (H to Ca) in the comma-separated format (e.g. 2,8,8,1 for a potassium atom). Define isotopes as atoms of an element with the same number of protons but different numbers of neutrons (so having different mass numbers). Use data to identify the relative abundances of isotopes. Understand that chemical composition can be identified from spectra. Understand the role of a mass spectrometer in identifying isotopes and the structure of molecules. Page 6

7 Atomic Structure Lesson 2 Medic Mind Tips and Theory There have been 5 questions on Atomic Structure since All questions on Atomic Structure thus far have tended to focus on electronic structure. The mass spectrometer, which is in the BMAT specification, has not yet been tested and is unlikely to come up on test day. In this chapter we will focus on electronic structure. The concepts are very important, so we will cover this topic in detail. Key Definitions Relative Atomic Mass (RAM): the average mass of 1 atom of an element, taking into account all of its isotopes and their relative abundances, relative to 1/12th the mass of a carbon-12 atom. Relative Isotopic Mass: the mass of an atom of 1 isotope relative to 1/12th the mass of a carbon-12 atom Relative Molecular Mass: the average mass of 1 molecule of a compound, found by calculating the sum of the relative atomic masses of the constituent atoms of the molecule. These are all measured relative to the single atomic mass unit, which is 1/12th the mass of a carbon-12 atom. Atomic Structure An atom is made up of a central nucleus, where most of the weight is concentrated. The protons and neutrons of the atom are found in the nucleus. The electrons orbit around the nucleus in shells, and are kept in orbit by electrostatic attractions between the protons in the nucleus and the electrons. Protons are positive, neutrons are neutral, electrons are negative. There are equal number of electrons and neutrons in uncharged species. Page 7

8 Atomic Structure Lesson 2 The number of protons defines the element. Electrons can be lost or gained (e.g. between Na and Na + ), but protons stay constant for a particular element. Periodic Table The periodic table is arranged in order of increasing atomic number The group of an element tells you the number of outer electrons. Isotopes Isotopes are atoms of the same element, with the same number of protons (so therefore still the same element) yet different number of neutrons. Therefore, they have the same atomic number, but a different mass number. Atomic Number and Mass Number Atomic number = number of protons Mass number = number of protons + number of neutrons Protons = 18 Neutrons = 22 Electrons = 18 Page 8

9 Atomic Structure Lesson 2 Electron Shells To find the number electrons, you just do mass number - atomic number. The electrons are arranged in shells. The first shell can hold 2 electrons at maximum. The second shell can hold 8 electrons at maximum. The third shell can hold 8 electrons at maximum. The fourth shell can hold 2 electrons at maximum. Chlorine has 18 electrons, so has an electron configuration of 2, 8, 8. Tips for BMAT Questions on Atomic Structure If they present ions, remember that only the electrons will be different to the neutral atom. Therefore the mass number and atomic number are unchanged. The atomic number defines the element. As soon as the atomic number is different, the element is different. Elements in the same group have similar properties Practice Questions Question 1 1. Be 2+ has 2 electrons 2. H + has no electrons 3. Se 2- and Fe together have 77 electrons. 4. The atomic number of Be 2+ is different to that of Be. 5. The mass number of H + is different to that of H. Page 9