Problem 8 - Chemistry and Chemical Reactivity

Question

Atomic structure. (a) The synthetic radioactive element technetium is used in many medical studies. Give the number of electrons, protons, and neutrons in an atom of technetium-99. (b) Radioactive americium- 241 is used in household smoke detectors and in bone mineral analysis. Give the number of electrons, protons, and neutrons in an atom of americium-241.

Step-by-Step Solution

Answer

Technetium-99: 43 electrons, 43 protons, 56 neutrons. Americium-241: 95 electrons, 95 protons, 146 neutrons.

Step 1: Identify Element Characteristics for Technetium-99

Technetium (Tc) is element number 43 on the periodic table, which means it has 43 protons and 43 electrons in its neutral state. The isotopic number (99) indicates the total number of protons and neutrons.

Step 2: Calculate Neutrons in Technetium-99

To find the number of neutrons, subtract the number of protons from the isotopic number: \(99 - 43 = 56\). Therefore, technetium-99 has 56 neutrons.

Step 3: Summarize Technetium-99 Atomic Structure

An atom of technetium-99 contains 43 electrons, 43 protons, and 56 neutrons.

Step 4: Identify Element Characteristics for Americium-241

Americium (Am) is element number 95 on the periodic table, which means it has 95 protons and 95 electrons in its neutral state. The isotopic number (241) indicates the total number of protons and neutrons.

Step 5: Calculate Neutrons in Americium-241

To find the number of neutrons, subtract the number of protons from the isotopic number: \(241 - 95 = 146\). Therefore, americium-241 has 146 neutrons.

Step 6: Summarize Americium-241 Atomic Structure

An atom of americium-241 contains 95 electrons, 95 protons, and 146 neutrons.

Key Concepts

Ionizing Radiation

Ionizing radiation is a fascinating, yet potentially harmful phenomenon characterized by the emission of energy in the form of either particles or electromagnetic waves. It has enough energy to ionize atoms or molecules by removing tightly bound electrons. This action can lead to various chemical reactions, significantly affecting living cells.

• Types of Ionizing Radiation: There are several types of ionizing radiation, including alpha particles, beta particles, and gamma rays. Each varies in their penetration power and potential biological impact.
• Applications: Ionizing radiation is utilized in a variety of fields, ranging from medical imaging and cancer radiotherapy to sterilizing medical equipment and food preservation.
• Risks: Prolonged exposure can lead to radiation sickness, increased cancer risks, and other health effects. However, in controlled medical uses, it helps diagnose and treat diseases safely.

To understand atomic structure problems, it's crucial to recognize how ionizing radiation relates to radioisotopes like technetium-99 and americium-241 used in medical and safety applications.

Isotopic Composition

The concept of isotopic composition is fundamental in understanding atomic structure. An isotope is an atom variant that has the same number of protons but different numbers of neutrons. This affects the atomic mass but not the chemical properties.

Isotopes are identified by their mass number, which is the sum of protons and neutrons. For example, technetium-99 and americium-241 are isotopes of technetium and americium, respectively. Each elemental isotope can be determined by the following:

• Mass Number: This is the total number of protons and neutrons found within an atom's nucleus.
• Example Calculation: For technetium-99, the mass number is 99. Given its atomic number is 43 (indicating protons), its neutron count is 56 (99 - 43).
• Stability: Some isotopes are stable, while others are radioactive, meaning they decay over time. Radioactive isotopes like technetium-99 are useful in medical tracing.

Understanding isotopic composition is key to detailing the number of essential particles in an atom, helping solve problems related to atomic structure.

Elementary Particles

Elementary particles form the backbone of atomic structure, consisting of protons, neutrons, and electrons. Each particle has unique properties and roles within an atom.

• Protons: These positively charged particles are found in the nucleus. They determine the atomic number and element identity. For example, technetium has 43 protons.
• Neutrons: These neutral particles also reside in the nucleus, contribute to atomic mass, and can vary between isotopes. Examples include the 56 neutrons in technetium-99.
• Electrons: Carrying a negative charge, electrons orbit the nucleus and are equal in number to protons in a neutral atom. Both technetium and americium in their atomic states have the same number of electrons and protons.

Understanding these elementary particles allows us to deduce the structure of various elements and their isotopes, crucial for exercises in atomic composition and applications in science.