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| Law of Conservation of Matter |
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Definition
| In chemical reactions, matter is neither created nor destroyed. |
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| Law of constant composition |
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| Each pure chemical compound always has the same percentage composition of each element. |
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1. All matter is composed of tiny, indivisible particles, called atoms, that cannot be created or destroyed.
2. Each element has atoms that are identical to each other in all of their properties, and these properties are different from the preerties of all other atoms.
3. Chemical reactions are simple rearrangements of atoms from one combination to another in small whole-number ratios.
(John Dalton, 1803-1808) |
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| Law of multiple proportions |
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Definition
When two elements can be combined to make two different compounds, and if samples of these two compouns are taken so that the masses of one of the elements in the two compounds are the same in both samples, then the ratio of the masses of the other element in these compounds will be a ratio of small whole numbers.
(John Dalton) |
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| Man who, in 1834, showed that electric current could cause chemical reactions to occur, demostrating the electric nature of the elements. |
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| An evacuated tube with two electrodes. When a high voltage was applied to the electrodes, a glow was noticed between them. When an object was placed in the path of the glow, it blocked part of the beam, proving that the beam must originate at the negative electrode(cathode) and flow toward the positive electrode(anode). |
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| Determined the electric charge to mass ratio of the C. rays (e/m= -1.76 * 106 coulombs gram -1) by measuring the deflection of the cathode rays in the presence of electric and magnetic fields. |
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