Understanding Transuranic Elements and the Actinide Series

The question asks to identify a specific metallic, radioactive, transuranic element. This element has an atomic number of 101, belongs to the actinide series, and was discovered in 1955.

Let's break down some key terms:

• Transuranic elements: These are chemical elements with atomic numbers greater than 92 (the atomic number of uranium). They are all radioactive.
• Actinide series: This is a series of 15 metallic chemical elements with atomic numbers from 89 (actinium) through 103 (lawrencium). Most actinides are transuranic elements. They are typically placed below the main body of the periodic table.
• Atomic number: This is the number of protons in the nucleus of an atom of an element. It uniquely identifies the element.

Identifying the Element with Atomic Number 101

We are looking for the element with an atomic number of 101. Let's consider the atomic numbers of the elements provided in the options:

• Nobelium (No): Atomic number 102.
• Seaborgium (Sg): Atomic number 106.
• Rutherfordium (Rf): Atomic number 104.
• Mendelevium (Md): Atomic number 101.

Based on the atomic number given in the question (101), the element must be Mendelevium (Md).

Confirming Other Properties: Discovery Year and Actinide Series

The question also states that the element was discovered in 1955 and is part of the actinide series. Let's verify this for Mendelevium:

• Mendelevium (Md) has an atomic number of 101.
• Elements with atomic numbers 89 through 103 belong to the actinide series. Since 101 falls within this range, Mendelevium is indeed an actinide.
• Mendelevium was first synthesized and identified in 1955 by a team led by Glenn T. Seaborg at the University of California, Berkeley.
• Mendelevium is a radioactive, metallic element.

All the properties mentioned in the question (atomic number 101, actinide series, discovered in 1955, metallic, radioactive, transuranic) match those of Mendelevium.

Let's briefly look at why the other options are incorrect based on their atomic numbers:

Only Mendelevium has an atomic number of 101.

Conclusion on the Metallic Radioactive Transuranic Element

The metallic radioactive transuranic element with atomic number 101, belonging to the actinide series, discovered in 1955, is Mendelevium.

Revision Table: Key Facts about Mendelevium

Additional Information: Naming of Transuranic Elements

Transuranic elements, especially those synthesized in laboratories, are often named after famous scientists or locations of their discovery. Mendelevium is named after Dmitri Mendeleev, the creator of the first version of the periodic table. This naming honors his significant contribution to chemistry.

Elements like Seaborgium are named after Glenn T. Seaborg, who was involved in the discovery of many transuranic elements, including Mendelevium. Rutherfordium is named after Ernest Rutherford, a pioneer in nuclear physics. Nobelium is named after Alfred Nobel, the founder of the Nobel Prizes.

Studying these elements helps us understand the behavior of matter under extreme conditions and expands our knowledge of the periodic table.