Atoms and Isotopes 1. Consider the data table below: | atom (or ion) of element | a | b | c | d | e | f | g | |---|---|---|---|---|---|---|---| | number of protons | 12 | 13 | 11 | 12 | 14 | 15 | 10 | | number of electrons | 12 | 10 | 10 | 12 | 14 | 18 | 10 | | number of neutrons | 12 | 14 | 12 | 13 | 14 | 16 | 10 | a. Which of the above species are negatively charged? f b. Which species are isotopes of the same element? a + d c. Using your periodic table give the conventional chemical symbol (including charge) for species A, B, and F. * a = Mg²⁺ * b = Al³⁺ * f = O²⁻ 2. The element X consists of three isotopes: ¹⁰X (25%), ¹¹X (65%), and ¹²X (10%). (a) Calculate the average atomic mass of element X. (10 x 0.25) + (11 x 0.65) + (12 x 0.1) = 10.85 amu (b) Are there any atoms of element X that weigh your reported average atomic mass? Explain. No, atomic mass is protons + neutrons, it must be a whole number. 3. How many niobium (Nb) atoms would it take to equal the mass of 48 magnesium (¹²Mg) atoms? 48 x 24.31 amu = 1166.88 / 92.91 = 12.56 ≈ 13 atoms 4. The element neon (Ne) is found in three isotopic forms: ²⁰Ne (10% abundant), ²¹Ne (80% abundant), and ²²Ne (10% abundant). Calculate the average atomic mass of Ne. Include the proper units with your answer. (19 x 0.1) + (20 x 0.8) + (21 x 0.1) = 20 amu 5. How many titanium (Ti) atoms (atomic #22) would it take to equal the mass of 100 iridium (Ir) atoms (atomic #77)? Show your work and circle your answer. 1 6. Element A is found in three isotopic forms: ³⁰A (14% abundant), ³¹A (42% abundant), and ³⁴A (44% abundant). Calculate the average atomic mass of element A and the proper units. (30 x 0.14) + (31 x 0.42) + (34 x 0.44) = 32.18 amu 7. What must be done to a neutral chlorine atom in order to change it into Cl⁻? Chlorine atom must gain 1 electron to make it Cl⁻ 8. Complete the following table: | Chemical Symbol | Atomic Number | Number of neutrons | Mass Number | Number of electrons | Net Charge | |---|---|---|---|---|---| | ³⁹K⁺ | 19 | 20 | 39 | 18 | +1 | | ¹⁰⁶Pd²⁺ | 46 | 60 | 106 | 44 | +2 | | ³²S | 16 | 16 | 32 | 18 | 0 | | ²⁰⁹Bi³⁺ | 83 | 126 | 209 | 80 | +3 | 9. Which two fundamental particles (e⁻, p⁺, n⁰) have about the same mass? p⁺ and n⁰ 10. What fundamental particle accounts for virtually all of an atom's volume? e⁻ 11. How does Ca²⁺ differ from Ca? Ca²⁺ has two less electrons 12. Given a neutral iron atom (Fe), what must be done to it in order to make it into an Fe²⁺ cation? Fe atom must lose 2 electrons

Atoms and Isotopes Key

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