Dalton's Atomic Theory (Dalton in 1808)
1.All matters are made of small particles i. e atoms
2.Atoms of same elements are indentical whereas atoms of different elements are different in all respect i.e shapes, size, weight, and properties.
3.Atoms is the smallest particles that takes part in chemical reactions.
4.Atoms cannot be splitted and created during chemical reaction.
1.Laws of Stiochiometry
In greek, stiochio means an elements and metry means measure which simply forms the measure of elements in combination.
Stiochiometry means The calculations which deals with the mass and volume relationships between reactants and products.There are laws of the Stiochiometry which are discussed below :
1.1:Law of conservation of mass
It was proposed by lavoiser and verified by landolt. According to this law; Total number of mass remains conserved during chemical reactions", "Mass is neither created nor destroyed in a chemical reaction"
consider a chemical reaction,
A + B --------> C + D
According to this laws,
mass of A + Mass of B = Mass of C + Mass of D
ie. Total mass of reactants =Total mass of the products
1.2 Law of Constant Proportion/composition
It was proposed by Proust.
it states that "A chemically pure same compound always contains the same elements combined together in the definite proportion by weight regardless of the origin or mode of formation
For example :
Pure water Always contains hydrogen and oxygen in ratio 1:8 by weight.
1.3 Law of Multiple Proportions
It was proposed by Dalton and verified by Berzelius.
It states "When two elements combine to form more than one compound then the different masses of one element which combine with a fixed mass of other elements, bear a simple whole number ratio"
FOR example :
Hydrogen and Oxygen combines to form two compounds water and hydrogen peroxide.
in water: 2 parts 16 parts
in Hydrogen peroxide :2 parts 32 parts
Thus, the weight of oxygen which combines with the same weight of Hydrogen(i. e 2 parts by weight) are in the simple ratio of 1:2. This is simple whole number. Hence, it illustrate the law of multiple proportions.
1.4 Law of reciprocal proportions
Proposed by Ritcher.
It states that" When two elements combine separately with a fixed mass of a third element, then the ratio of their masses in which they do so is either same or some whole number multiple of ratio in which they combine with each other.
1.5 Gay lussac's law of gaseous volumes
It states "The volumes of the gaseous reactants and products in a chemical reaction bear a simple ratio(i. e simple whole number ratio) if the volumes are measured at similar conditions of temperature and pressure"
Considering a chemical reaction
H2+ Cl2 ------------------> 2HCL
1 volume 1 volume. 2 volume
volume of H2:Cl2:HCL which is simple whole no. ratio.
hence it illustrates the law of gaseous volumes.