January 2015 Chemistry Regents #1-5
Highlight to reveal answers and explanations
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Questions | Answer | Links | Explanations |
| 1 According to the modern model of the atom, the nucleus of an atom is surrounded by one or more (1) electrons (3) positrons (2) neutrons (4) protons | 1 | Link | electrons are outside the nucleus in the cloud |
| 2 Which particle has a mass of approximately 1 atomic mass unit? (1) an alpha particle (3) an electron (2) a beta particle (4) a neutron | 4 | Link | look at the mass number on table N or know that protons and neutrons have a mass of 1 amu |
| 3 A specific amount of energy is emitted when excited electrons in an atom in a sample of an element return to the ground state. This emitted energy can be used to determine the (1) mass of the sample (2) volume of the sample (3) identity of the element (4) number of moles of the element | 3 | Link | Line Spectra is unique to every element and can be used to identify an element |
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| 4 According to the wave-mechanical model, an orbital is defined as the (1) circular path for electrons (2) circular path for neutrons (3) most probable location of electrons (4) most probable location of neutrons | 3 | Link | An orbital is defined as the most probable location for finding an electron. |
| 5 All phosphorus atoms have the same (1) atomic number (2) mass number (3) number of neutrons plus the number of electrons (4) number of neutrons plus the number of protons | 1 | Link | No two elements have the same atomic number (or the same number of protons), so the atomic number identifies the element. |
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