11 Class Chapter 1- Some Basic Concept of Chemistry
Some Basic Concept Of Chemistry
Some Basic Concept Of Chemistry
Basic constituents of matter:- Atoms and molecules.
What is chemistry:- It is the branch of science which deals with the study of composition, properties and interaction of matter.
Matter:- Anything which has mass and occupies space known as matter. Ex:- Water, pencil, pen, book etc.
Physical states of matter
=>Solid, liquid, gas.
Temperature & pressure effect on physical state
Classification of matter: –
1.Mixture: – It contains two or more substances in any ration known as its components.
Ex: – air, tea etc.
a.Homogeneous mixture:- its components are completely mix with each other and have uniform composition throughout the solution.
Ex:- sugar solution, air.
b.Heterogeneous mixture:- its components do not have uniform composition throughout solution sometimes different components observed.
Ex:- mixture of salt & sugar, sand & soil.
2.Pure substances:- these have fixed composition.
Ex:- copper, gold, water etc.
a.Elements:- It consists of only one type ofparticles (i.e. atoms or molecules)
Ex:- H2, O2, Au, Ag.
b.Compounds:- It consist of two or more atoms to give a molecule of compound
Ex:- CO2, NH3, H2O.
Properties of matter
1)Physical properties:- Those properties which can be measured or observed.
2)Chemical properties:– those properties in which chemical changes occurs.
Ex:– Acidity, Basicity, Combustibility etc.
SI :- International System of units
ØEstablished by 11th general conference on weight and measures.
ØSi have seven fundamental units
ØOther units are divided from seven fundamental units
Base physical quantity
Symbol for quantity
SI units name
SI units symbol
Amount of substance
Prefixes for SI Units
Mass:- amount of matter in object
=>1 kg = 1000 gram
Weight: -force on the object by gravity.
=>1 L = 1000 ml, 1000 cm3 = 1dm3
Density:- Amount of mass per unit volume.
=>SI unit :- Kgm-3
Temperature:- It is the measurement of cooling or warming.
=>0C (Degree Celsius)
=>0F degree Fahrenheit)
=>freezing point of water = 0 0C
=>Boiling point of water = 100 0C
k = 0C + 273.15
Precision:- Closeness of various measurement for same quantity.
Accuracy:- It is the agreement of a particular value to the true value of the result.
Significant figure:- The meaningful digits which are known with certainty.
Laws of chemical combinations
1)Law of conservation of mass:- According to this law “matter can neither be created nor destroyed” Given by Antone Lovoisin in 1789.
2)Law of definite proportion:– According to this law “A given compound always contains exactly the same proportion of elements by weight known as law of definite proportion or law of definite composition” given by Joseph Proust in 1754-1826
3)Law of multiple proportion:- According to this law “if two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of small whole number” given by Dalton in 1803.
4)Gay lussac’s law of gaseous volume:- According to this law “gases combine or are produced in chemical reactions they do so in a simple ratio by volume provided to all gases are at thesame temperature and pressure” given by Gay Lussac’s in 1808.
5)Avogadro’s law:- According to this law “Equal volume of gases at same temperature & pressure should contain equal no. of molecules” given by Avogadro in 1811.
Dalton’s Atomic Theory
i.Matter consists of indivisible atoms.
ii.All the atoms of a element have identical properties (same properties) i.e. atoms of a element have same mass while atoms of different elements have different masses.
iii.Compounds formed when atoms of different elements combine in fixed ratio.
iv.Chemical reactions involve reorganization (rearrangement) of atoms.
Atomic mass unit = 1/12thmass of one carbon12 atom.
Molecular mass = It is the sum of atomic masses of the elements present in a molecule.
Mole :- It is the amount of substance equal to Avogadro no. (NA). = 6.022 ´ 1023 atoms/mole.
Molar mass:- Mass of one mol of a substances in gram is known as molar mass.
Mass % of an element = mass of that element in compound ´100/ molar mass of the compound.
Empirical formula :- It is the simplest whole no. ratio of various atoms present in a compound.
Molecular formula:- It is the exact no. of different types of atoms present in a molecule of a compound.
Concentration expression methods
ii.Mole fraction :- If a substance ‘A’ is dissolved in ‘B’ and their no. of moles are nA and nBrespectively.