WORKSHEET CH. 2 1) Knowing the atomic number of an element tells you which of th
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Question
WORKSHEET CH. 2 1) Knowing the atomic number of an element tells you which of the following? protons in the element B) the number of neutrons in the element C) the number of electrons in the element D) the number of protons plus neutrons in the element E) both the number of protons and the number of electrons in the element 2 2) The nucleus of a specific carbon atom contains 7 neutrons and 6 protons. Which of the following is a correct statement concerning this atom of carbon? A) This carbon atom has a mass number of approximately 7 daltons and an atomic number of 13. B) This carbon atom has a mass number of approximately 13 daltons and an atomic number of 7 C) This carbon atom has a mass number of 12 and an atomic number of 6. D) This carbon atom has a mass number of 12 and an atomic number of 7 E) This carbon atom has a mass number of 13 and an atomic number of 6 3) In the diagram of the two atoms of hydrogen below, the atomic number is a subscript and the atomic mass is a superscript Atom 1 Atom 2 Which of the following statements concerning these two atoms is correct? A) They are isomers B) They contain 1 and 3 electrons, respectively C) They are isotopes D) They contain 1 and 3 protons, respectively E) They each contain 1 neutron. 4) An atom has S electrons in its outer shell. How many unpaired electrons does it have? A) 0 B) 1 C) 2 D) 3 E) 5 5) Electrons in an atom vary in the amount of energy they possess, and are therefore located in shells or levels. Electrons that are in energy shells that are more distant from the nucleus have more potential energy: However, if an electron absorbs energy such as light A) the electron may move to an electron shell farther away from the nucleus. B) the electron may move to an electron shell closer to the nucleus C) the atom would become a positively D) the atom would become a negatively charged ion, or anion. E) the atom may become a radioactive isotope charged ion, or cation, and become a radioacti 6) How many electrons are needed to complete the valence shell of a sulfur atom? B) 2 C) 3 D) 6Explanation / Answer
1. A
The atomic number or proton number (symbol Z) of a chemical element is the number of protons found in the nucleus of an atom. It is identical to the charge numberof the nucleus. The atomic number uniquely identifies a chemical element. In an uncharged atom, the atomic number is also equal to the number of electrons.
2.E
C-13 is the isotope of Carbon. 6C13 , 6 protons with 7 neutrons.
3.C
(They are isotopes ) ( same atomic number with different mass number )
4. B
Boron has electronic configuration 1s2 2s2 2p1 ( 5 electrons 2+2+1)
5. A
When an electron absorbs energy, it jumps to a higher orbital. An electron in an excited state can release energy and 'fall' to a lower state.
6. B
Sulfur Electron configuration, [Ne] 3s23p4. it needs 2 electrons to complete valence shell equal to Argon.
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