1. The concept of positive charge and a small, “heavy” nucleus surrounded by electrons was the contribution of Dalton Rutherford (c) Thomson (d) Chadwick
1. The concept of positive charge and a small, “heavy” nucleus surrounded by electrons was the contribution of Dalton Rutherford (c) Thomson (d) Chadwick
2. An atom of atomic number 53 and mass number 127 contains how many neutrons? (a) 53 (b) 74 (c) 127 (d) 180
2. An atom of atomic number 53 and mass number 127 contains how many neutrons? (a) 53 (b) 74 (127-53) (c) 127 (d) 180
3. How many electrons are in an atom of 4018Ar ? (b) 22 (c) 40 (d) no correct answer given
3. How many electrons are in an atom of 4018Ar ? (b) 22 (c) 40 (d) no correct answer given (neutral, p = e- = 18)
4. The number of neutrons in an atom of 139 56Ba is (a) 56 (b) 83 (c) 139 (d) no correct answer given
4. The number of neutrons in an atom of 139 56Ba is (a) 56 (b) 83 (139-56) (c) 139 (d) no correct answer given
5.The name of the isotope containing one proton and two neutrons is (a) protium (b) tritium (c) deuterium (d) helium
5. The name of the isotope containing one proton and two neutrons is (a) protium 11H (b) tritium 31H (c) deuterium 21H (d) helium
6. Each atom of a specific element has the same (a) number of protons (b) atomic mass (c) number of neutrons (d) no correct answer given
6. Each atom of a specific element has the same (a) number of protons (atomic #) (b) atomic mass (c) number of neutrons (d) no correct answer given
7. Which pair of symbols represents isotopes? (a)2311Na and 2312Na (b) 73Li and 63Li (c) 63 29Cu and 2964Cu (d) 1224Mg and 1226Mg
7. Which pair of symbols represents isotopes? (a)2311Na and 2312Na (b) 73Li and 63Li (c) 63 29Cu and 2964Cu (d) 1224Mg and 1226Mg
8. Two naturally occurring isotopes of an element have masses and abundance as follows: 54.00 amu (20.00%) and 56.00 amu (80.00%). What is the relative atomic mass of the element? (a) 54.20 (b) 54.40 (c) 54.80 (d) 55.60
8. Two naturally occurring isotopes of an element have masses and abundance as follows: 54.00 amu (20.00%) and 56.00 amu (80.00%). What is the relative atomic mass of the element? (a) 54.20 (b) 54.40 54.00 (.2000) = 10.80 (c) 54.80 56.00 (.8000) = 44.80 (d) 55.60 55.60
9. Substance X has 13 protons, 14 neutrons, and 10 electrons. Determine its identity. (a) 27Mg (b) 27Ne (c) 27Al3+ (d) 27Al
9. Substance X has 13 protons, 14 neutrons, and 10 electrons. Determine its identity. (a) 27Mg (b) 27Ne (c) 27Al3+ (d) 27Al
10.The number of neutrons in an atom of 10847Ag is (a) 47 (b) 108 (c) 155 (d) no correct answer given
10. The number of neutrons in an atom of 10847Ag is (a) 47 (b) 108 (c) 155 (d) no correct answer given (108 – 47 = 61)
11. The number of electrons in an atom of 2713Al is (a) 13 (b) 14 (c) 27 (d) 40
11. The number of electrons in an atom of 2713Al is (a) 13 (neutral, p = e- = 13) (b) 14 (c) 27 (d) 40
12. The number of protons in an atom of 6530Zn is (a) 65 (b) 35 (c) 30 (d) 95
12. The number of protons in an atom of 6530Zn is (a) 65 (b) 35 (c) 30 (d) 95
13. The number of electrons in the nucleus of an atom of 2412Mg is (a) 12 (b) 24 (c) 36 (d) no correct answer given
13. The number of electrons in the nucleus of an atom of 2412Mg is (a) 12 (b) 24 (c) 36 (d) no correct answer given
Free Response Questions 14. What is an ion?
Free Response Questions 14. What is an ion? An ion is a charged atom or group of atoms. The charge can be either positive (“cation” - resulting from a loss of e-) or negative (“anion” – resulting from a gain of e-).
15. The average mass of a calcium atom is 40.08 amu. Why do we also use 40.08 amu as the average mass of a calcium ion (Ca2+ )?
15. The average mass of a calcium atom is 40.08 amu. Why do we also use 40.08 amu as the average mass of a calcium ion (Ca2+ )? Electrons have negligible mass compared to the mass of protons and neutrons. The only difference between Ca and Ca2+ is two electrons. The mass of those two electrons is insignificant compared to the mass of the protons and neutrons present (and whose numbers do not change).