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17 Cards in this Set
- Front
- Back
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Atom
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the smallest piece of an element which retains the property of that element
composed of sub(under or inside) atomic particles, protons neutrons electrons |
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Dalton's Atomic Theory
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1 All elements are composed of tiny invisible atoms
2 All atoms of the same element are identical in mass and size and different from atoms of other elements 3 Atoms can combine in whole number ratios to form compounds 4 Chemical reactions occur when atoms are joined together, separated, or re-arranged. |
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Law of Definite Composition
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a compound always contains two or more elements combined in a definite proportion by mass
ex water = H O, salt = NaCl |
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Law of Multiple Proportions
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atoms of two or more elements can form more than one compound
H O = water H O = hydrogen peroxide C H O = glucose C H O = ethanol |
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proton
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positively charged (+1)
inside nucleus mass=1.67X10 g = 1 amu |
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neutron
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neutral charge (0)
inside nucleus mass =1.67X10 g = 1 amu |
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electron
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negatively charged (-1)
outside nucleus mass= 9.11X10 g =1/2000 amu |
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amu
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Atomic Mass Unit
the approximate mass of 1 proton or 1 neutron |
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Cathode Ray Tube Experiment
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proved negatively charged particles exist (predicited to be electrons)
gas is negatively charged |
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Ruthefords Gold Foil Experiment
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1 Atoms are mostly empty space
2 There does exist inside the atom a very very small very dense nucleus 3 The nucleus is positively charged and spherical |
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Atomic Number
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the largest number inside the box with the chemical symbol. Tells how many protons the atom has in its nucleus
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Mass Number
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# of protons + # of neutrons
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Atoms are electrically neutral
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# of protons= # of neutrons
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Isotopic symbol
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chemical symbol which shows the mass number of the element
98 Ag Or Ag-98 |
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Isotopes
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atoms of the same element with different numbers of neutrons, therefore, different mass numbers
ex: S-32, S-33, S-34, S-36 |
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Average atomic mass
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found on the periodic table is a weighted average of al known isotopes
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How to calculate weighted average
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1- multiply the % abundance (given) by the mass number for each isotope
2- sum these numbers |
