Title ALLEN Chemistry Module (1-6)Complete.pdf ✅

1 h apter 01 Contents SOME BASIC CONCEPTS OF CHEMISTRY : General Introduction: Importance and scope of chemistry. concept of elements, atoms and molecules. Atomic and molecular masses. Mole concept and molar mass; percentage composition and empirical and molecular formula; chemical reactions, stoichiometry and calculations based on stoichiometry. Laws of chemical combination, Dalton’s atomic theory: Precision and accuracy, Significant figures Some Basic Concept of Chemistry NEET SYLLABUS 01. Introduction 3 (a) Matter 3 (b) SI units 5 (c) Prefixes used with units 5 (d) Unit conversions 6 02. Mole Concept 8 03. Percentage composition empirical 14 formula and molecular formula 04. Stoichiometry 16 (a) Single reactant based 17 (b) More than one reactant based 19 05. Equivalent weight 20 (a) Calculation of equivalent weight 20 (b) Number of gram equivalent and 21 law of equivalence (c) Methods for determination of 21 equivalent weight 06. Methods for determination of 22 atomic weight and molecular weight 07. Laws of chemical combination 25 08. Exercise-I (Conceptual Questions) 30 09. Exercise-II (Previous Year Questions) 39 10. Exercise-III (Analytical Questions) 41
2 OBJECTIVES After studying this unit, we will be able to : • understand and appreciate the role of chemistry in different spheres of life; • explain the characteristics of three states of matter; • classify different substances into elements, compounds and mixtures; • explain various laws of chemical combination; • appreciate significance of atomic mass, average atomic mass and molecular mass. • describe the terms – mole and molar mass; • calculate the mass percentage of different elements constituting a compound; • determine empirical formula and molecular formula for a compound from the given experimental data; • perform the stoichiometric calculations. "Chemistry is the melodies you can play on vibrating strings" Michio Kaku
ALLEN Pre-Medical : Chemistry 3 Z:\NODE02\B0B0-BA\TARGET\CHEM\ENG\MODULE-1\1.SOME BASIC CONCEPTS OF CHEMISTRY\01-THEORY.P65 E SOME BASIC CONCEPTS OF CHEMISTRY 1.0 INTRODUCTION Chemistry deals with the composition, structure and properties of matter. These aspects can be best described and understood in terms of basic constituents of matter: atoms and molecules. That is why chemistry is called the science of atoms and molecules. Can we see, weight and perceive these entities? Is it possible to count the number of atoms and molecules in a given mass of matter and have a quantitative relationship between the mass and number of these particles (atoms and molecules)? We will like to answer some of these questions in this Unit. We would further describe how physical properties of matter can be quantitatively described using numerical values with suitable units. MATTER PHYSICAL Solid Liquid Gas definite shape & volume no definite shape & volume definite volume but no definite shape CHEMICAL Pure Substances Mixtures fixed ratio of masses of constituents Elements Compounds Homogeneous Heterogeneous same composition throughout & components are indistinguishable. eg. gases, liquid solution, alloys, atmospheric air nearly homogeneous Consists of only one type of atoms Made of two or more atoms of different elements composition is not uniform. eg. sand & water, Classification of universe Universe is classified into two types i.e. matter and energy. (A) MATTER : The thing which occupy space and having mass which can be felt by our five senses is called matter. Matter is further classified into two categories : (I) Physical classification (II) Chemical classification PHYSICAL CLASSIFICATION It is based on physical state under ordinary conditions of temperature and pressure, so on the basis of two nature of forces matter can be classified into the following three ways : (a) Solid (b) Liquid (c) Gas (a) Solid : A substance is said to be solid if it possesses a definite volume and a definite shape. e.g. Sugar, Iron, Gold, Wood etc. (b) Liquid : A substance is said to be liquid if it possesses a definite volume but not definite shape. They take the shape of the vessel in which they are placed. e.g. Water, Milk, Oil, Mercury, Alcohol etc. (c) Gas : A substance is said to be gas if it neither possesses a definite volume nor a definite shape. This is because they completely occupy the whole vessel in which they are placed. e.g. Hydrogen(H2 ), Oxygen(O2 ), Carbon dioxide(CO2 ) etc.