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How many protons and how many neutrons are there in a nucleus of the most common isotope of (a) silicon, \(^{28}_{14}Si\); (b) rubidium, \(^{85}_{37}Rb\); (c) thallium, \(^{205}_{81}Tl\)?

Short Answer

Expert verified
(a) 14 protons, 14 neutrons; (b) 37 protons, 48 neutrons; (c) 81 protons, 124 neutrons.

Step by step solution

01

Understanding Nuclear Symbols

Each nuclear symbol is written in the form \( ^{A}_{Z}X \), where \( A \) is the mass number, \( Z \) is the atomic number, and \( X \) is the chemical symbol of the element. The atomic number \( Z \) represents the number of protons and thus identifies the element.
02

Finding Protons in Silicon

For silicon \( ^{28}_{14}Si \), the atomic number \( Z \) is 14. Therefore, the number of protons in silicon is 14.
03

Calculating Neutrons in Silicon

The mass number \( A \) for silicon is 28. To find the number of neutrons, use the formula: Neutrons = Mass number - Atomic number. For silicon, Neutrons = 28 - 14 = 14.
04

Finding Protons in Rubidium

For rubidium \( ^{85}_{37}Rb \), the atomic number \( Z \) is 37. Therefore, the number of protons in rubidium is 37.
05

Calculating Neutrons in Rubidium

The mass number \( A \) for rubidium is 85. To find the number of neutrons, use the formula: Neutrons = Mass number - Atomic number. For rubidium, Neutrons = 85 - 37 = 48.
06

Finding Protons in Thallium

For thallium \( ^{205}_{81}Tl \), the atomic number \( Z \) is 81. Therefore, the number of protons in thallium is 81.
07

Calculating Neutrons in Thallium

The mass number \( A \) for thallium is 205. To find the number of neutrons, use the formula: Neutrons = Mass number - Atomic number. For thallium, Neutrons = 205 - 81 = 124.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Nuclear Symbols
Nuclear symbols play a crucial role in understanding the fundamentals of nuclear physics. They provide a shorthand way to denote the specific characteristics of an element's nucleus. The format for nuclear symbols is typically expressed as \( ^{A}_{Z}X \), where each part has its own distinct meaning:
  • \( A \) is the mass number, representing the total number of protons and neutrons within the nucleus.
  • \( Z \) is the atomic number, which indicates the number of protons in the nucleus, determining the element's identity.
  • \( X \) is the chemical symbol of the element, such as Si for silicon, Rb for rubidium, or Tl for thallium.
When interpreting nuclear symbols, focus on these values to understand the composition of the nucleus. This notation aids in calculating the number of neutrons as well, using the mass and atomic numbers.
Protons and Neutrons
Protons and neutrons together form the nucleus of an atom, and their arrangement significantly influences the atom's properties. Protons are positively charged particles, and their number, given by the atomic number, defines the element. Neutrons, on the other hand, are neutral particles that essentially serve as a "glue," helping to bind protons together within the nucleus despite their mutual repulsion due to like charges.
  • Protons determine the charge and identity of the atom.
  • Neutrons contribute to the mass of the atom and influence its stability.
The balance between protons and neutrons is crucial for the atom's stability. This balance can vary among isotopes, which are atoms of the same element with different numbers of neutrons. Understanding the roles of protons and neutrons helps in predicting the chemical behavior and stability of elements.
Atomic Number
The atomic number, denoted by \( Z \), is a fundamental concept in nuclear physics. It specifies the number of protons found in the nucleus of an atom. Since protons are positively charged, the atomic number also reflects the charge of the nucleus.- The atomic number is unique for each element and determines its position in the periodic table.- For example, silicon has an atomic number of 14, rubidium 37, and thallium 81.The atomic number is crucial because it dictates how atoms interact chemically with each other. Elements with the same atomic number but different mass numbers are known as isotopes, possessing varied numbers of neutrons.
Mass Number
Mass number, symbolized as \( A \), represents the total number of protons and neutrons in an atom's nucleus. Unlike the atomic number, the mass number can change in isotopes of the same element due to a different count of neutrons.
  • For example, silicon's mass number is 28, rubidium's is 85, and thallium's is 205.
  • It's calculated as: \( A = \ ext{Number of protons} + \ ext{Number of neutrons} \).
Knowing the mass number allows for the calculation of the number of neutrons by using the formula: \[\text{Neutrons} = A - Z \]Where \( A \) is the mass number and \( Z \) is the atomic number. The mass number's variability among isotopes influences the atomic mass seen in periodic tables.

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Most popular questions from this chapter

As a health physicist, you are being consulted about a spill in a radiochemistry lab. The isotope spilled was 400 \(\mu\)Ci of \(^1$$^3$$^1\)Ba, which has a half-life of 12 days. (a) What mass of \(^1$$^3$$^1\)Ba was spilled? (b) Your recommendation is to clear the lab until the radiation level has fallen 1.00 \(\mu\)Ci. How long will the lab have to be closed?

\(^2$$^3$$^8\)U decays spontaneously by \(\alpha\) emission to \(^2$$^3$$^4\)Th. Calculate (a) the total energy released by this process and (b) the recoil velocity of the \(^2$$^3$$^4\)Th nucleus. The atomic masses are 238.050788 u for \(^2$$^3$$^8\)U and 234.043601 u for \(^2$$^3$$^4\)Th.

In an industrial accident a 65-kg person receives a lethal whole-body equivalent dose of 5.4 Sv from x rays. (a) What is the equivalent dose in rem? (b) What is the absorbed dose in rad? (c) What is the total energy absorbed by the person's body? How does this amount of energy compare to the amount of energy required to raise the temperature of 65 kg of water 0.010 C\(^{\circ}\)?

A nuclear chemist receives an accidental radiation dose of 5.0 Gy from slow neutrons (RBE \(=\) 4.0). What does she receive in rad, rem, and J/kg?

Measurements indicate that 27.83% of all rubidium atoms currently on the earth are the radioactive \(^8$$^7\)Rb isotope. The rest are the stable \(^8$$^5\)Rb isotope. The half-life of \(^8$$^7\)Rb is 4.75 \(\times\) 10\(^1$$^0\) y. Assuming that no rubidium atoms have been formed since, what percentage of rubidium atoms were \(^8$$^7\)Rb when our solar system was formed 4.6 \(\times\) 10\(^9\) y ago?

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