Indietro
- Give the names and symbols for the following elements: (a) An element with atomic number 6 (b) An element with 18 protons in its nucleus (c) An element with 23 electrons
Problema 100
- The radioactive isotope cesium-137 was produced in large amounts in fallout from the 1985 nuclear power plant disas-ter at Chernobyl, Ukraine. Write the symbol for this isotope in standard format.
Problema 101
- Write symbols for the following isotopes: (a) Radon-220 (b) Polonium-210 (c) Gold-197
Problema 102
- Write symbols for the following isotopes: (a) Z = 58 and A = 140 (b) Z = 27 and A = 60
Problema 103
Problema 104a
How many protons, neutrons, and electrons are in each of the following atoms? (a)
Problema 104b
How many protons, neutrons, and electrons are in each of the following atoms? (b)
Problema 104c
How many protons, neutrons, and electrons are in each of the following atoms? (c)
Problema 104d
How many protons, neutrons, and electrons are in each of the following atoms? (d)
Problema 105a
How many protons and neutrons are in the nucleus of the following atoms? (a)
Problema 105b
How many protons and neutrons are in the nucleus of the following atoms? (b)
Problema 105c
How many protons and neutrons are in the nucleus of the following atoms? (c)
Problema 105d
How many protons and neutrons are in the nucleus of the following atoms? (d)
- Identify the following elements: (a)
Problema 106
- Which of the following isotope symbols can't be correct? (a) (b) (c) (d)
Problema 108
Problema 109
The molar mass of HCl is 36.5 g/mol, and the average mass per HCl molecule is 36.5 u. Use the fact that 1 u = 1.6605 * 102 24g to calculate Avogadro's number.
- Fluorine occurs naturally as a single isotope. How many protons, neutrons, and electrons are present in deuterium fluoride (2HF)? (Deuterium is 2H.)
Problema 110
- Hydrogen has three isotopes (1H, 2H, and 3H), and chlorine has two isotopes (35Cl and 37Cl). How many isotopic kinds of HCl are there? Write the formula for each, and state how many protons, neutrons, and electrons each contains.
Problema 111
- The unified atomic mass unit (u) 1/12 the mass of a neutral atom of: (a) 1^H (b) 12^C (c) 14^C (d) 16^O
Problema 112
Problema 113a
(a) The unified atomic mass unit (u) is used to represent the extremely small mass of atoms. How many grams are equivalent to 1 u?
Problema 113b
(b) The mole is a unit used to represent a very large number of atoms. How many atoms are equivalent to 1 mol of atoms?
- Match the descriptions (a)–(e) with the following terms: atomic weight, atomic mass, mass number, atomic number, molar mass. (a) The mass of a specific atom such as one atom of 13C (b) The quantity determined by the number of protons in an element. (c) The number of grams in 1 mol of an element (d) The number of protons and neutrons in an element (e) The weighted average of the isotopic masses of an element's naturally occurring isotopes
Problema 114
- Label the following statements as true or false. (a) The atomic weight and the atomic number of an element have the same numerical value. (b) The molar mass in grams for an element and the atomic weight have the same numerical value.
Problema 115
- Copper has two naturally occurring isotopes, including 65Cu. Look at the periodic table and tell whether the second isotope is 63Cu or 66Cu.
Problema 116
- A copper wire having a mass of 2.196 g was allowed to react with an excess of sulfur. The excess sulfur was then burned, yielding SO2 gas. The mass of the copper sulfide produced was 2.748 g. (c) Calculate the number of copper ions per cubic centimeter if the density of the copper sulfide is 5.6 g/cm3.
Problema 117
- Naturally occurring boron consists of two isotopes: 10^B (19.9%) with an isotopic mass of 10.0129 and 11^B (80.1%) with an isotopic mass of 11.009 31. What is the atomic weight of boron? Check your answer by looking at a periodic table.
Problema 118
Problema 119
Naturally occurring silver consists of two isotopes: 107^Ag (51.84%) with an isotopic mass of 106.9051 and 109^Ag (48.16%) with an isotopic mass of 108.9048. What is the atomic weight of silver? Check your answer in a periodic table.
Problema 120
Magnesium has three naturally occurring isotopes: 24Mg (23.985) with 78.99% abundance, 25Mg (24.986) with 10.00% abundance, and a third with 11.01% abundance. Look up the atomic weight of magnesium, and then calculate the mass of the third isotope.
- A sample of naturally occurring silicon consists of 28^Si (27.9769), 29^Si (28.9765), and 30^Si (29.9738). If the atomic weight of silicon is 28.0855 and the natural abundance of 29^Si is 4.68%, what are the natural abundances of 28^Si and 30^Si?
Problema 121
- Copper metal has two naturally occurring isotopes: copper-63 (69.15%; isotopic mass = 62.93) and copper-65 (30.85%; isotopic mass 64.93). Calculate the atomic weight of copper, and check your answer in the periodic table.
Problema 122
- Germanium has five naturally occurring isotopes: 70^Ge, 20.5%, 69.924; 72^Ge, 27.4%, 71.922; 73^Ge, 7.8%, 72.923; 74^Ge, 36.5%, 73.921; and 76^Ge, 7.8%, 75.921. What is the atomic weight of germanium?
Problema 123