Question

Assume that the number of protons in a neutral atom is 92 and its mass number is 238 . a. What is the name of the element? b. How many electrons does it have? c. How many neutrons does it have?

Short answer

The element is Uranium, it has 92 electrons, and 146 neutrons.

Step-by-step solution

Identify the Element by Proton Number

The element can be identified by its number of protons, which is also its atomic number. Since the number of protons is 92, we look at the periodic table and find that the element with atomic number 92 is Uranium, symbolized as 'U'.

Determine the Number of Electrons

Since the atom is neutral, the number of protons is equal to the number of electrons to balance the charge. Therefore, with 92 protons, the atom also has 92 electrons.

Calculate the Number of Neutrons

The mass number of an atom is the sum of its protons and neutrons. Given the mass number is 238 and the number of protons is 92, the number of neutrons is calculated as follows: \( \text{Neutrons} = 238 - 92 = 146 \). So, the atom has 146 neutrons.

Key concepts

Protons

Protons are one of the main constituents of an atom. They reside in the nucleus and carry a positive charge. Each proton in an atom contributes to the atomic number, which fundamentally defines the chemical identity of the element. For example, in the case of Uranium, it possesses 92 protons. This means that it has an atomic number of 92. Hence, irrespective of other sub-atomic particles, the presence of 92 protons identifies the element as Uranium.

Neutrons

Neutrons are neutral particles, which means they carry no charge. Like protons, they are located in the nucleus of an atom. Their primary role is to add mass and stability to the atom. The number of neutrons can vary even within atoms of the same element, leading to different isotopes. For Uranium with a mass number of 238 and 92 protons, the neutrons number is calculated as: \[ ext{Neutrons} = 238 - 92 = 146 \] So, this Uranium atom has 146 neutrons, contributing to its physical mass and isotopic nature.

Electrons

Electrons are negatively charged particles that orbit the nucleus of an atom in various energy levels. They balance the positive charge of protons in a neutral atom, which means their number is equal to the number of protons. For Uranium, which has 92 protons, there are also 92 electrons. These electrons are responsible for chemical reactions and bonding with other atoms.

Atomic Number

The atomic number of an atom is important as it is directly synonymous with the number of protons in the atom's nucleus. This number defines the element's identity and its position in the periodic table. In the case of Uranium, the atomic number is 92. This unique number ensures that any atom with 92 protons is always recognized as Uranium, irrespective of the number of neutrons or electrons present.

Mass Number

The mass number of an atom is the total count of protons and neutrons in the nucleus. It gives the atom a measure of its total mass. It is expressed as follows:\[ ext{Mass Number} = ext{Protons} + ext{Neutrons} \]For Uranium, the mass number is given as 238. This includes 92 protons, and when we know this, we can calculate the number of neutrons, coming to a total of 146 neutrons.

Uranium

Uranium is a well-known heavy element, chemically represented by the symbol 'U'. It plays a significant role in the nuclear energy industry due to its radioactive properties. With an atomic number of 92, Uranium is the heaviest naturally occurring element found in abundance. Its mass number can vary, but the isotope Uranium-238 is very common, having 92 protons and 146 neutrons, demonstrating its unique attributes and stability among nuclear isotopes.