January 2016 Chemistry Regents #1-5
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Questions | Answer | Links | Explanations |
1. Which phrase describes the charge and mass of a neutron? (1) a charge of +1 and no mass (2) a charge of +1 and an approximate mass of l u. (3) no charge and no mass (4) no charge and an approximate mass of l u. | 4 | Neutron mass = 1amu no charge | |
2. What is the number of electrons in a potassium atom? (1) 18 (3) 20 (2) 19 (4) 3 | 2 | 2-8-8-1 add them up and you get 19 also the atomic number is protons (and electron in an atom) atoms are neutral | |
3. The number of valence electrons in each atom of an element affects the element's (1) chemical properties (3) decay mode (2) number of isotopes (4) half-life | 1 | valence electrons determine reactivity, bonding ratios...chemical properties | |
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4. The nuclides I-131 and I-133 are classified as (1) isomers of the same element (2) isomers of Xe-131 and Cs-133 (3) isotopes of the same element (4) isotopes of Xe-131 and Cs-133 | 3 | isotopes- same number of protons (so same element) different number of neutrons (so different mass number) | |
5. The elements on the Periodic Table are arranged in order of increasing (1) mass number (2) atomic number (3) number of isotopes (4) number of valence electrons | 2 | atomic number....look at periodic table | |
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