Textbook Question
Use the mass spectrum of mercury to estimate the atomic mass of mercury. Estimate the masses and percent intensity values from the graph to three significant figures.
Ch.2 - Atoms & Elements
Chapter 2, Problem 105
Fill in the blanks to complete the table. Symbol Z A Number of p Number of e− Number of n Charge ______ 8 ______ ______ ______ 8 2- Ca2 + 20 ______ ______ ______ 20 ______ Mg2 + ______ 25 ______ ______ 13 2+ N3 - ______ 14 ______ 10 ______ ______
Verified step by step guidance1
Step 1: Identify the element with atomic number (Z) 8. This corresponds to oxygen (O).
Step 2: For the oxygen ion (O^2-), calculate the number of electrons. Since the charge is 2-, it has gained 2 electrons, so the number of electrons is Z + 2.
Step 3: For Ca^2+, the atomic number (Z) is 20, which means it has 20 protons. The charge is 2+, indicating it has lost 2 electrons, so the number of electrons is Z - 2.
Step 4: For Mg^2+, the mass number (A) is 25. The number of neutrons is A - Z. Since the charge is 2+, it has lost 2 electrons, so the number of electrons is Z - 2.
Step 5: For N^3-, the atomic number (Z) is 7 (since nitrogen is element 7). The charge is 3-, indicating it has gained 3 electrons, so the number of electrons is Z + 3. The number of neutrons is A - Z.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Atomic Number (Z)
The atomic number (Z) of an element is the number of protons found in the nucleus of an atom. It uniquely identifies an element and determines its position in the periodic table. For example, an atomic number of 8 corresponds to oxygen, which has 8 protons and, in a neutral atom, also 8 electrons.
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Atomic Mass
Mass Number (A)
The mass number (A) is the total number of protons and neutrons in an atom's nucleus. It is calculated by adding the number of protons (Z) to the number of neutrons (n). For instance, if an element has an atomic number of 20 and 20 neutrons, its mass number would be 40.
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Ionic Charge
Ionic charge refers to the net electrical charge of an atom or molecule, resulting from the loss or gain of electrons. Cations, like Ca2+ and Mg2+, have a positive charge due to the loss of electrons, while anions, like N3-, have a negative charge from gaining electrons. The charge affects the number of electrons compared to protons in the atom.
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Related Practice
Textbook Question
Nuclei with the same number of neutrons but different mass numbers are called isotones. Write the symbols of four isotones of 236Th.
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Textbook Question
Neutron stars are composed of solid nuclear matter, primarily neutrons. Assume the radius of a neutron is approximately 1.0×10–13 cm. Calculate the density of a neutron. [Hint: For a sphere V = (4/3)πr3.] Assuming that a neutron star has the same density as a neutron, calculate the mass (in kg) of a small piece of a neutron star the size of a spherical pebble with a radius of 0.10 mm.
Textbook Question
Carbon-12 contains six protons and six neutrons. The radius of the nucleus is approximately 2.7 fm (femtometers) and the radius of the atom is approximately 70 pm (picometers). Calculate the volume of the nucleus and the volume of the atom.
Textbook Question
Carbon-12 contains six protons and six neutrons. The radius of the nucleus is approximately 2.7 fm (femtometers) and the radius of the atom is approximately 70 pm (picometers). What percentage of the carbon atom's volume is occupied by the nucleus? (Assume two significant figures.)