QUICK REVISION
Matter : Anything that has mass and occupies space.
Precision : If refers to the closeness of various measurements for the same quantity.
Accuracy : It refers to the agreement of a particular value to the true value of the result.
Mass and weight : Mass of a substance is the amount of matter present in body, while weight is the force exerted by gravity on an object. The mass of a substance is constant whereas its weight may vary from one place to another due to change in gravity.
Law of Multiple Proportions (John Dalton) : When two elements combine to form two or more compounds, then the different masses of one element, which combine with a fixed mass of the other, bear a simple ratio to one another.
Gay Lussac’s Law : When gases combine or are produced in a chemical reaction, they do so in a simple ratio provided all gases are in the same temperature and pressure.
Atomic Mass : It is defined as the average relative mass of an atom of an element as compared to the mass of an atom of carbon – 12 taken as 12. Atomic mass is represented by ‘u’ (unified mass).
Molecular mass : It is algebraic the sum of the atomic mass of the elements present in the molecule
Avogadro Number : It is the amount of atoms or molecules present in one mole of a substance.
Molar Mass : The mass of one mole of a substance in grams is called its molar mass.
Empirical Formula : It represents the simplest whole number ratio of various atoms present in a compound. For e.g., CH is the empirical formula of benzene.
Molecular Formula : It shows the exact number of different of atoms present in a molecule of a compound. For e.g., C6H6 is the molecular formula of benzene.
Limiting Reagent : It is the reactant which gets consumed first or limits the amount of product formed.
Mass Percent : It is the mass of the solute in grams per 100 grams of the solution.