Term
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Definition
400 BC
Founded Atoms
Called them indivisible. |
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Term
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Definition
Refuted atoms.
Thought that all matter was continuous. |
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Term
| Law of Conservation of Mass |
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Definition
| Mass is neither destroyed nor created during ordinary chemical or physical reactions. |
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Term
| Law of Definite Proportions |
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Definition
| A chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound. |
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Term
| Law of Multiple Proportions |
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Definition
| If two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers. |
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Term
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Definition
1808
Explained the law of conservation of mass, law of definite proportions and the law of multiple proportions. |
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Term
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Definition
1. All matter is composed of extremely small particles called atoms.
2. Atoms of a given element are identical size, mass, and other properties; atoms of different elements differ in size, mass, and other properties.
3. Atoms can not be subdivided, created, or destroyed.
4. Atoms of different elements combine in simple, whole number ratios to form chemical compounds.
5. In chemical reactions, atoms are combined, separated, or rearranged. |
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Term
| Two of Dalton's Points Proven Wrong |
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Definition
Atoms ARE divisible into smaller particles.
A given element can have atoms with different masses. |
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Term
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Definition
| Smallest particle of an element that retains the chemical properties of that element. |
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Term
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Definition
| Founded electrons by observing cathode ray tubes. |
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Term
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Definition
Found that the electron is much much smaller than the smallest atom of an element.
Also discovered that the electron has a negative charge. |
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Term
| Atomic Structure Inferences |
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Definition
1. Because atoms are electrically neutral, they must contain a positive charge to balance the negative electrons.
2. Because electrons have so much less mass than atoms, atoms must contain other particles that account for most of their mass. |
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Term
| Ernst Rutherford, Hans Geiger and Ernest Marsden |
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Definition
Founded the nucleus of the atom.
Also founded the electron cloud. |
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Term
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Definition
| Short range proton-neutron, proton-proton, and neutron-neutron forces hold the nuclear particles together. |
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Term
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Definition
| Number of protons in a nucleus of each atom of that element. |
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Term
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Definition
| Atoms of the same element that have different masses. |
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Term
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Definition
| total number of protons and neutrons in the nucleus of an isotope. |
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Term
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Definition
| General term for any isotope for any element. |
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Term
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Definition
| The unit that is equal to the mass of carbon-12 and is used as a relative measurement of the periodic table. |
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Term
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Definition
| the weighted average of the atomic masses of the naturally occurring isotopes of that element. |
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Term
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Definition
| Amount of a substance that contains as many particles as there are atoms in exactly 12g of carbon-12. |
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Definition
| (6.022 X10tothe23rd) the number of particles in exactly one mole of a pure substance. |
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Term
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Definition
| The mass of one mole of a pure substance. |
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Term
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Definition
| Amt. of element in moles X 6.022x1023=Number of atoms. |
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Term
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Definition
| Number of atoms X 1/6.022x1023=Moles |
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Term
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Definition
| Number of atoms X 1/(6.022x1023) X molar mass of element=Mass in grams. |
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Term
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Definition
| Mass of element X 1/Molar Mass of element x(6.022x1023)=Atoms |
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Term
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Definition
| Mass of element x 1/molar mass of element=Moles |
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Term
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Definition
| Moles X molar mass of element = Mass of element |
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Term
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Definition
1 mole=6.022X1023 atoms
1 mole= molar mass of element |
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