Question

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

Short answer

a. Uranium b. 92 electrons c. 146 neutrons

Step-by-step solution

Determine the Element Name

The element is identified by its atomic number, which is the number of protons in the atom. Since the number of protons is 92, we look up the periodic table to find the corresponding element. The element with atomic number 92 is Uranium.

Determine the Number of Electrons

In a neutral atom, the number of electrons is equal to the number of protons. Therefore, if the number of protons is 92, the number of electrons is also 92.

Calculate the Number of Neutrons

To find the number of neutrons, subtract the atomic number (number of protons) from the mass number. The mass number is 238. Therefore, the number of neutrons is 238 - 92 = 146.

Key concepts

Periodic Table

The Periodic Table is a powerful tool in chemistry and physics. It organizes all known chemical elements based on their atomic number, which represents the number of protons in each atom. Each element has a unique atomic number, making it distinct from others. The periodic table is crucial for identifying the properties of elements. For example, when solving problems related to atomic structure, knowing an element's location on the periodic table can help determine its chemical behavior and characteristics. Elements are arranged in rows and columns that reflect similarities in element properties, aiding in the prediction of chemical reactions and trends.

In atomic theory, the periodic table serves as a reference point for the properties of each element, helping students and scientists alike in understanding and visualizing the stable and reactive nature of different substances.

Protons

Protons are subatomic particles found in the nucleus of an atom. They carry a positive electrical charge and play a key role in defining the identity of an element. The number of protons in an atom is known as the atomic number, which is unique for each element. For instance, Uranium has 92 protons. This not only gives us its atomic number but also positions it in the periodic table.

Protons contribute significantly to the mass of an atom and help determine its chemical characteristics. The force between protons and other subatomic particles like electrons and neutrons affects the atom's stability and how it will interact with other atoms.

Electrons

Electrons are small, negatively charged particles that orbit the nucleus of an atom. In a neutral atom, the number of electrons is equal to the number of protons. They play a critical role in chemical bonding and reactions, as the interactions between electrons of adjacent atoms lead to the formation of molecules.

For example, in a Uranium atom, which has 92 protons, there are also 92 electrons. These electrons are arranged in energy levels or shells around the nucleus. Their arrangement determines how an atom will interact with other atoms, heavily influencing both its chemical properties and reactivity.

Neutrons

Neutrons are neutrally charged particles found in the nucleus alongside protons. Unlike protons, they do not have an electrical charge. Neutrons play a crucial role in maintaining the stability of the nucleus, especially in larger atoms. They help offset the repulsive forces between protons due to their like charges.

The number of neutrons in an atom can vary, leading to different isotopes of the same element. The mass number, which is the total number of protons and neutrons in an atom, helps determine which isotope it is. For Uranium, which has a mass number of 238, there are 146 neutrons, calculated by subtracting the number of protons (92) from the mass number.

Mass Number

The mass number of an atom is the sum of its protons and neutrons. It reflects the total mass of the nucleus. Unlike the atomic number, the mass number can vary even within atoms of the same element due to different numbers of neutrons. This variation gives rise to isotopes of an element.

For instance, Uranium has a mass number of 238, indicating that the nucleus contains 238 protons and neutrons combined. The mass number is crucial in nuclear chemistry and physics, as it helps determine an atom's stability and the types of nuclear reactions it can undergo.

Uranium

Uranium is a heavy metal element with the atomic number 92, meaning it has 92 protons and, in its neutral state, 92 electrons. It is widely known for its radioactive properties and its significance in the nuclear energy industry.

Uranium is found in two primary isotopes—Uranium-238 and Uranium-235, with Uranium-238 being the most abundant. The different isotopes have the same number of protons but different numbers of neutrons, which results in different physical properties. Understanding Uranium's atomic structure provides insights into its applications, especially in nuclear fission, where Uranium-235 plays a pivotal role in generating energy through its ability to sustain a chain reaction.