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Ch.2 - Atoms, Molecules, and Ions
Chapter 2, Problem 91a

(a) Assuming the dimensions of the nucleus and atom shown in Figure 2.10, what fraction of the volume of the atom is taken up by the nucleus?

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insert step 1: Understand the problem by identifying the given information. You need the dimensions of both the nucleus and the atom. Assume the nucleus is a sphere with radius r_nucleus and the atom is a sphere with radius r_atom.
insert step 2: Use the formula for the volume of a sphere, V = \frac{4}{3}\pi r^3, to calculate the volume of the nucleus.
insert step 3: Similarly, use the same formula to calculate the volume of the atom.
insert step 4: Determine the fraction of the volume of the atom that is occupied by the nucleus by dividing the volume of the nucleus by the volume of the atom.
insert step 5: Simplify the expression to find the fraction, which will be a very small number, indicating that the nucleus occupies a tiny fraction of the atom's volume.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Atomic Structure

Atoms consist of a nucleus, which contains protons and neutrons, surrounded by electrons in various energy levels. The nucleus is significantly smaller than the entire atom, which includes the electron cloud. Understanding the relative sizes of these components is crucial for calculating volume fractions.
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Atom Structure

Volume Calculation

The volume of a sphere can be calculated using the formula V = (4/3)πr³, where r is the radius. To find the fraction of the atom's volume occupied by the nucleus, one must calculate the volumes of both the atom and the nucleus and then divide the nucleus's volume by the atom's volume.
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Constant-Volume Calorimetry

Fractional Volume

The fractional volume is a ratio that compares the volume of a part to the total volume. In this context, it is the volume of the nucleus divided by the volume of the atom, expressed as a decimal or percentage. This concept helps quantify how much space the nucleus occupies relative to the entire atom.
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Related Practice
Textbook Question

"The diameter of a rubidium atom is 495 pm We will consider two different ways of placing the atoms on a surface. In arrangement A, all the atoms are lined up with one another to form a square grid. Arrangement B is called a close-packed arrangement because the atoms sit in the 'depressions' formed by the previous row of atoms:

(c) By what factor has the number of atoms on the surface increased in going to arrangement B from arrangement A?

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Textbook Question

"The diameter of a rubidium atom is 495 pm We will consider two different ways of placing the atoms on a surface. In arrangement A, all the atoms are lined up with one another to form a square grid. Arrangement B is called a close-packed arrangement because the atoms sit in the 'depressions' formed by the previous row of atoms:

(c) If extended to three dimensions, which arrangement would lead to a greater density for Rb metal?"

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Textbook Question
Very small semiconductor crystals, composed of approximately 1000 to 10,000 atoms, are called quantum dots. Quantum dots made of the semiconductor CdSe are now being used in electronic reader and tablet displays because they emit light efficiently and in multiple colors, depending on dot size. The density of CdSe is 5.82 g/cm3. (b) CdSe quantum dots that are 2.5 nm in diameter emit blue light upon stimulation. Assuming that the dot is a perfect sphere and that the empty space in the dot can be neglected, calculate how many Cd atoms are in one quantum dot of this size.
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Textbook Question

(b) Using the mass of the proton from Table 2.1 and assuming its diameter is 1.0 * 10-15 m, calculate the density of a proton in g>cm3.

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Textbook Question

Identify the element represented by each of the following symbols and give the number of protons and neutrons in each: (a) 7433X

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Textbook Question

Identify the element represented by each of the following symbols and give the number of protons and neutrons in each: (b) 12753X (c) 8636X (d) 6730X

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