Topic 1: Atoms, Molecules and Stoichiometry



2324929-139148SMK SEKSYEN 10 KOTA DAMANSARA47810 PETALING JAYA, SELANGOR-1104905715 CHEMISTRY MODULE (FIRST TERM, 2012) TOPIC 1 : ATOMS, MOLECULES AND STOICHIOMETRYCHECKLIST TO SCORE A IN CHEMISTRY(Tick after tutorial /revision class)TopicSub-topicsTick1.1 Fundamental describe the properties of protons, neutrons, and electrons in terms of their relative charges and relative massesparticles of an atompredict the behaviour of beams of protons,neutrons, and electrons in both electric and magnetic fieldsdescribe the distribution of mass and charges within an atomdetermine the numbers of protons, neutrons, and electrons present in both neutral and charged species of a given proton number and nucleon numberdescribe the contribution of protons and neutrons to atomic nuclei in terms of proton and nucleon numberdistinguish between isotopes based on the Number of neutrons present; state examples of both stable and unstable isotopes1.2 Relative atomic, isotopic,define the terms relative atomic mass, Ar, relative isotopic mass, relative molecular mass, Mr, and relative formula mass based on 12C;molecular &formula massesinterprete mass spectra in terms of relative abundance of isotopes and molecular fragments;calculate relative atomic mass of an element from the relative abundance of its isotopes or its mass spectrum.1.3 define mole in terms of the Avogadro constant;The mole and theAvogadrocalculate the number of moles of reactants, volumes of gases, volumes and concentrations of solutions;constant226702133742deduce stoichiometric relationships from the calculations above**SEKIRANYA MASIH ADA SUB-TOPIC YANG TIDAK FAHAM, SILA JUMPA GURU ANDA DENGAN SEGERA ATAU MEMBUAT ULANGKAJI SERTA-MERTA. PRACTICE MAKE PERFECTSub-topic 1.1 : Fundamental particles of an atomLearning outcomes: Candidates should be able to:(a) describe the properties of protons, neutrons and electrons in terms of their relative charges and relative masses;(b) predict the behaviour of beams of protons, neutrons and electrons in both electric and magnetic fields;(c) describe the distribution of mass and charges within an atom;(d) determine the number of protons, neutrons and electrons present in both neutral and charged species of a given proton number and nucleon number; (e) describe the contribution of protons and neutrons to atomic nuclei in terms of proton number and nucleon number;(f) distinguish isotopes based on the number of neutrons present, and state examples of both stable and unstable isotopes.The properties of the subatomic particles of an atom:ParticleSymbolChargeRelative mass (a.m.u)ProtonNeutronElectronThe effect of electric field on subatomic particles:The effect of magnetic field on subatomic particles:In this atomic model (James Chadwick):(a) The nucleus of an atom consists of ___________ and ____________ occupying a small space in the centre of the atom.(b) Electrons are moving around the nucleus in permissible orbits or electron shells (also known as quantum shells).The distribution of mass and charges within an atom:This implies that a big section of an atom is made up of empty space. However, 99.98% of the mass of the atom is concentrated in the nucleus.Number of neutron in a nucleus = nucleon number – proton numberElementSymbolNumber of protonsNumber of nucleonsNumber of electronsNo. of electronsAluminiumAluminium ionArgonBeryllium BoronCalciumCarbonChlorineChloride ionFluorineFluoride ionHeliumHydrogenLithium Lithium ionMagnesiumNeonNitrogenOxygenPhosphorusPotassiumThe contribution of protons and neutrons to atomic nuclei in terms of proton number and nucleon numberThe ____________________is the number of protons in the nucleus of an atom. Atoms are neutral particles. Hence, the number of protons in the nucleus of an atom is the same as the number of electrons surrounding the nucleus.The elements in the Modern Periodic Table are arranged in ascending order of proton numbersIsotopes are atoms of the same element with the same __________ number but different ________ number.The isotopes of an elementhave the same __________ properties because they have the same electron arrangement but their __________ properties differ.Stable isotopes : the nuclei of stable isotopes will not disintegrate spontaneouslyUnstable isotopes = radioactive isotopes, which will disintegrate spontaneously by emitting alpha particles (α particles, 42He2+), beta particles (β particles, 0-1e) and gamma-rays (γ rays) which are electromagnetic waves with very short wavelength. This disintegration is known as radioactive decay. Sub-topic 1.2 : Relative atomic,isotopic, molecular & formula massesLearning outcomes: Candidates should be able to:define the terms relative atomic mass, Ar, relative isotopic mass, relative molecular mass, Mr, and relative formula mass based on 12C;interprete mass spectra in terms of relative abundance of isotopes and molecular fragments;calculate relative atomic mass of an element from the relative abundance of its isotopes or its mass spectrum.Relative atomic mass, Ar = the average mass of an atom of the element compared to 1/12 the mass of 12C Relative molecular mass, Mr = the ratio of the average mass of 1 molecule of a substance to 1/12 the mass of 12CRelative isotopic mass = the ratio of the mass of an atom of the isotope to 1/12 the mass of 12CFormula:Relative formula mass = the ratio of the average mass of 1 molecule of ionic compound to 1/12 the mass of 12CMass SpectrometryIs used to determine theRelative isotopic massRelative abundance of an isotopes in a sample of the elementRelative atomic massRelative molecular massStructure of organic compoundsApparatus used : mass spectrometer Relative abundance h1 h2 a b m/eAr = ah1 + bh2 h1+h2relative abundance/isotopic abundance = the abundance of each isotope in the mixture. It can be express in terms of fractional abundance or percentage abundance.The mass spectrum of methane :The CH4+ is called the molecular ion (M) or the parent ion and appear at the m/e value of 16, corresponding to the Mr of methane. Naturally occurring carbon is made up of 99% of 12C isotope and 1% 13C isotope (peak M+1). The peak M+1 can be ignored in the determining of the Mr of the compound. The mass spectrum of ethanol :Sub-topic 1.2 : Relative atomic,isotopic, molecular & formula massesLearning outcomes: Candidates should be able to:define mole in terms of the Avogadro constant;calculate the number of moles of reactants, volumes of gases, volumes and concentrations of solutions;deduce stoichiometric relationships from the calculations above.One mole is defined as the quantity of a substance that contains the same number of particles ( atoms, ions, or molecules) as there are atoms in exactly 12g of 12C. The number of atoms present in 1 mol of 12C is called the Avogadro constant and is equivalent to 6.02 X 1023.Source :,Ace Ahead Chemistry Volume 1, Oxford FajarChemistry for SPM, Cengage LearningPre-U Text STPM Physical Chemistry, LongmanSuccess Chemistry SPM, Oxford Fajar ................
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