Question

Draw the partial (valence-level) orbital diagram, and write the symbol, group number, and period number of the element: (a) \([\mathrm{He}] 2 s^{2} 2 p^{4}\) (b) \([\mathrm{Ne}] 3 s^{2} 3 p^{3}\)

Short answer

a) [He] 2s^2 2p^4; Symbol: O; Group: 16; Period: 2. b) [Ne] 3s^2 3p^3; Symbol: P; Group: 15; Period: 3.

Step-by-step solution

Identify the element for each electron configuration

Determine the element by counting the total number of electrons from the configuration provided.

Draw the partial (valence-level) orbital diagram for each configuration

For each configuration, illustrate the distribution of electrons in the valence orbitals (2s, 2p for part a, and 3s, 3p for part b).

Determine the symbol, group number, and period number of the element

Identify the symbol, group number, and period number of the element using the periodic table.

Key concepts

Valence-Level Orbital Diagram

The valence-level orbital diagram shows how electrons are distributed in the outermost shell of an atom. This part is crucial because it determines how elements interact in chemical reactions.
When drawing this diagram, focus only on the valence orbitals, where the highest energy electrons reside. This simplifies understanding of the atom's chemical behavior.

For example, in the electron configuration \( [ \text{Ne} ] 3s^{2} 3p^{3} \), we only consider the 3s and 3p orbitals to create the valence-level diagram.
An orbital can hold two electrons, and they must have opposite spins. The diagram helps visualize the pairing of electrons in these orbitals.

Periodic Table

The periodic table is a powerful tool that organizes elements based on their atomic number, electron configurations, and recurring chemical properties.
Each row in the table represents a period, and each column denotes a group.

• Periods: Elements in the same horizontal row have the same number of electron shells.
• Groups: Elements in the same vertical column have similar chemical properties due to equivalent valence electron configurations.

Using the table, you can identify an element by its symbol, atomic number, and position in a specific group and period.

Group Number

Group numbers indicate the number of valence electrons in an atom's outer shell. These electrons are critical in determining how elements interact and bond:
Elements in the same group have the same number of valence electrons, resulting in similar chemical behaviors. For example, all Group 1 elements, like sodium (Na) and potassium (K), have one valence electron.
The group number can sometimes be directly related to the number of valence electrons, especially for main-group elements:

• Group 1: 1 valence electron
• Group 2: 2 valence electrons
• Groups 13-18: 3 to 8 valence electrons, respectively

By knowing the group number, you can predict an element's reactivity and bonding patterns.

Period Number

The period number of an element tells us how many electron shells are occupied by electrons in the atom.
Each period on the periodic table corresponds to a new electron shell. For instance, all elements in the 2nd period have two electron shells.
The period number helps determine the size and energy level of an atom's outer shell, impacting the element's chemical properties.

• For example, elements in Period 2, like oxygen (O) and nitrogen (N), have their valence electrons in the second shell.
• Elements in Period 3, such as sodium (Na) and sulfur (S), have their valence electrons in the third shell.

This systematic organization helps predict and explain periodic trends, such as atomic size and ionization energy.