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Description
Flashcards by crystal.clark, updated more than 1 year ago
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Created by crystal.clark
almost 10 years ago
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| Question | Answer |
| Atom | Made of even smaller particles called proton, neutrons and electrons |
| Protons | Has a positive charge Indicated by the plus symbol, + |
| Neutrons | Have no charge They are neutral |
| Electrons | Move rapidly around the neucleus They has a negative charge Shown by the the symbol, e- |
| Neucleus | Is the very small center core of the atom |
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Dalton Model
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1808 Believe that each element is made of atoms that are alike |
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Thompson Model
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1897 Believed atoms are a positively charged sphere with electron embedded |
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Rutherford Model
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1911 Believed atoms are mostly empty space with electrons orbiting randomly around a small positively charged nucleus |
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Bohr Model
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1913 Believe electrons moved in specific layers (like a onion) |
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The Present Model
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Electrons form a negatively charged cloud around the neucleus |
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Atomic number
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Equals the number of protons in the neucleus The number on top in the periodic table 35 in this example |
| Isotopes | The same number of protons with a different number of neutrons |
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Mass number
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Sum of the protons and neutrons The number on the bottom in the periodic table 79.904 in this example |
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Chemical symbol
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Is usually on or two letters that are abbreviation of the English or Latin names Example Br = Bromine Potassium = Kalium = K |
| Period | The horizontal rows in the periodic table |
| Groups | The elements in a column Also known as families |
| Metals | Physical properties are shininess, malleability, ductility and conductivity |
| Malleable | One that can be hammered or rolled into flat sheets or other shapes |
| Ductile | One that can be pulled out or drawn into long wire |
| Conductivity | The ability of an object to transfer heat or electricity |
| Reactivity | The ease or speed with which an element combines or reacts with other elements and compounds |
| Alkali Metals | Metals in group 1 React with other elements by losing 1 electron Ver reactive; rarely found uncombined |
| Alkaline Earth Metals | Group 2 Fairly hard, gray-white and good conductor Loses 2 electrons Never found uncombined in nature |
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Transition Metals
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Elements in group 3 to 12 Most are hard and shiny and form colorful compounds All are good conductors of electricity Less reactive than metal in group 1&2 |
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Lanthanides
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The top row of the 2 rows of elements placed below the main part of the periodic table Soft, malleable, shiny with high conductivity. They are mixed with more common metals to make alloys |
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Actinides
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Below the lanthanides on the periodic table The nuclei of these elements are unstable, meaning they break apart quickly into smaller nuclei So unstable they only last a fraction of a second after they are made |
| Synthetic Elements | Elements with atomic numbers higher than 92 They are not found naturally on Earth Example: plutonium |
| Particle Accelerators | Move atomic nuclei faster and faster until they reach very high speed |
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