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15 Cards in this Set
- Front
- Back
What is John Dalton’s atomic theory?
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All elements are composed of atoms. All atoms of the same element have the same mass. A compound contains atoms of more than one element.
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In an atomic model that includes a nucleus, where is the positive charge?
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in the center of an atom
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What are the 3 subatomic particles of an atom?
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protons, neutrons, electrons
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What are the symbols and charge of the subatomic particles?
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P+ = protons (positive)
N = neutrons (neutral) E- = electrons (negative) |
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What are the differences between the subatomic particles?
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protons and neutrons are found in the nucleus, electrons are found outside the nucleus. Protons and neutrons have close to the same mass, while electrons have much less mass.
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How do you determine the number of protons an element has?
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atomic number
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How do you find the number of neutrons in an atom?
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subtract atomic number from the mass number
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What is an isotope? Give an example
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same element with different number of neutrons.
Oxygen (oxygen-17 and oxygen-18) |
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What can you assume has happened if an electron moves to a higher energy level?
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the electron has gained energy
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What is the difference between an atom in the ground state and an atom in an excited state?
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the atom in an excited state has more energy and is less stable than the atom in the ground state
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How was the usefulness of Mendeleev’s periodic table confirmed?
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the discovery of elements with predicted properties
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On the periodic table, which direction do groups go? (across/rows or down/columns) Periods? (across/rows or down/columns)
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groups - down/columns
periods - across/rows |
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How many valence electrons do elements that are the most reactive tend to have?
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1 or 7
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As you move from left to right across a row of the periodic table, what value increases by exactly one from element to element?
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atomic number (number of protons)
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What is relative to the tendency of an element to react chemically?
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the number of valence electrons in atoms of the element
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