Question

An element has 2 electrons in its \(\mathrm{K}\) shell, 8 electrons in \(\mathrm{L}\) shell, 13 electrons in \(\mathrm{M}\) shell and one electron in N shell. The element is: (a) \(\mathrm{Cr}\) (b) \(\mathrm{Fe}\) (c) \(\mathrm{V}\) (d) Ti

Short answer

The element is Chromium (Cr).

Step-by-step solution

Understanding Electron Configuration

To identify the element, we first recognize that the question involves electron configuration notation. The electron arrangement given is 2 in the K shell, 8 in the L shell, 13 in the M shell, and 1 in the N shell.

Determine Total Number of Electrons

Add the number of electrons in each shell: 2 (K) + 8 (L) + 13 (M) + 1 (N) = 24 electrons. This total gives us the atomic number of the element, which corresponds to the number of electrons for a neutral atom.

Identify the Element

With an atomic number of 24, we look up the periodic table. Element 24 is Chromium (Cr). Therefore, the atom with this electron arrangement matches Chromium.

Key concepts

K shell

The K shell is the innermost shell of an atom where electrons reside. It can hold a maximum of 2 electrons. Think of this shell as the first rung on a ladder. These electrons are closest to the nucleus, where they experience the strongest attraction due to electromagnetic forces.
In electron configuration, shells are also called energy levels, and the K shell is known as the "first" energy level. It is crucial in determining the chemical nature of an atom. For an element like Chromium, with an atomic number of 24, the K shell acts as the foundation for the electron arrangement.
If this shell is filled, it provides stability and completes the first layer of electron arrangement, influencing the atom's reactivity and bonding characteristics.

L shell

The L shell is the second shell in an atom, which can hold a maximum of 8 electrons. It's a step up from the K shell, accommodating more electrons and thus, has a significant impact on an element’s properties.
When considering electron configurations, the L shell comes into play after the K shell is filled. The presence of electrons in the L shell influences the atom's size and its interactions with other atoms. In elements beyond the first, the L shell helps in taking the electron count further, which is especially vital for elements like Chromium.

• The L shell helps to create the main energy level framework needed for the element's overall electron cloud.
• It provides further insight into the effective nuclear charge experienced by electrons.
• The filling of this shell plays a role in an element’s placement on the periodic table.

M shell

The M shell is the third shell and can hold up to 18 electrons. This shell is significant as it represents mid-level energy capacity within an atom's structure. It's where electrons begin to spread out and influence more complex chemical behaviors.
For heavier elements like Chromium, the electron configuration gets interesting as the M shell can support more electrons than the two shells before it. The presence of 13 electrons in the M shell, such as with Chromium, indicates a significant contribution to the atom's energy profile and chemical reactivity.
Understanding the distribution of electrons among different shells helps in predicting how atoms might interact, form bonds and contribute to the atom’s chemical identity.

Periodic Table

The Periodic Table serves as an essential tool in chemistry for understanding elemental properties and relationships. It organizes elements based on increasing atomic numbers, which is directly related to electron configuration. Each position of an element on the table provides clues about its chemical characteristics.
For example, Chromium with its atomic number 24 is positioned in a spot that highlights its electron arrangement: 2 electrons in the K shell, 8 in the L shell, 13 in the M shell, and 1 in the N shell. The table is structured within rows (periods) and columns (groups) that provide insight into the valence electrons and potential bonding behavior of the elements.

• Elements with similar electron shell structures are often found in the same column.
• The periodic table aids in predicting the types of chemical reactions an element can undergo.
• Knowing the position of an element in the periodic table helps in understanding its physical and chemical properties due to trends like electronegativity and atomic radii.