Question

The \(\mid P_{1}, I P_{2}, I P_{3}, I P_{4}\) and \(I P_{5}\) of an element are \(7.1\), \(14.3,34.5,46.8,162.2 \mathrm{eV}\), respectively. The element is likely to be (1) \(\mathrm{Na}\) (2) Si (3) \(\mathrm{F}\) (4) \(\mathrm{Ca}\)

Short answer

Si

Step-by-step solution

- Identify the data

List the given ionization potentials (IP values):\[ \begin{align*} IP_1 &= 7.1 \, \text{eV} \ IP_2 &= 14.3 \, \text{eV} \ IP_3 &= 34.5 \, \text{eV} \ IP_4 &= 46.8 \, \text{eV} \ IP_5 &= 162.2 \, \text{eV} \end{align*} \]

- Understand the meaning of IP values

Ionization potential (IP) is the energy required to remove an electron from an atom. A large difference between consecutive IPs indicates the removal of an electron from a new electron shell.

- Compare the jumps in IP values

Compare the differences between successive IP values: \[ \begin{align*} IP_2 - IP_1 &= 14.3 - 7.1 = 7.2 \, \text{eV} \ IP_3 - IP_2 &= 34.5 - 14.3 = 20.2 \, \text{eV} \ IP_4 - IP_3 &= 46.8 - 34.5 = 12.3 \, \text{eV} \ IP_5 - IP_4 &= 162.2 - 46.8 = 115.4 \, \text{eV} \end{align*} \]

- Identify the element

Notice the significant increase between IP_4 and IP_5 (115.4 eV), which suggests a stable noble gas configuration after the fourth electron is removed. Determine the element with four valence electrons before reaching a stable configuration. The element 'Si' (Silicon) fits this criterion.

Key concepts

Ionization Energy

Ionization energy, also referred to as ionization potential (IP), is the amount of energy required to remove an electron from a gaseous atom or ion. This energy is necessary to overcome the electrostatic force that binds the electron to the nucleus. Higher ionization energies indicate that more energy is needed to pull the electron away.

The trend in ionization energy across periods (rows) and down groups (columns) in the periodic table can help determine the reactivity and stability of elements. For example:

• Across a period, ionization energy generally increases as the atomic number increases, due to stronger attraction between the nucleus and electrons.
• Down a group, ionization energy generally decreases because the added electron shells increase the distance between the nucleus and outer electrons, reducing the nuclear attraction.

Understanding ionization energies helps predict which elements are likely to participate in chemical reactions by losing or gaining electrons.

Chemical Elements

Chemical elements are pure substances consisting of only one type of atom. Each element is defined by its atomic number, which indicates the number of protons in the nucleus. This unique number determines the element's identity and properties.

The periodic table organizes elements based on their atomic number, electron configurations, and recurring chemical properties. Elements are also classified into different categories such as metals, nonmetals, and metalloids.

• Metals are generally good conductors of heat and electricity, and they are malleable and ductile.
• Nonmetals, on the other hand, are poor conductors and tend to be brittle when solid.
• Metalloids exhibit properties of both metals and nonmetals, making them useful in various industrial applications.

Understanding the characteristics of elements helps in predicting and explaining the behavior of different substances in chemical reactions.

Periodic Table

The periodic table is a tabular arrangement of chemical elements ordered by their atomic number, electron configurations, and recurring chemical properties. Elements in the same column, known as groups, possess similar valence electron configurations, which results in similar chemical behavior.

Here are some important features of the periodic table:

• Periods are the horizontal rows of the table. As you move from left to right across a period, properties change progressively.
• Groups are the vertical columns. Elements in the same group have similar properties and react in similar ways.
• Transition metals, located in the center of the periodic table, often have variable oxidation states and form colored compounds.

The periodic table helps in predicting chemical reactions, understanding element properties, and organizing chemistry knowledge systematically.

Electron Configuration

Electron configuration describes the distribution of electrons in an atom or molecule. Electrons occupy energy levels or shells around the nucleus, and each shell comprises subshells (s, p, d, f) with specific shapes and capacities.

The electron configuration follows the Aufbau principle, which states that electrons fill the lowest energy orbitals first. Other important principles include:

• Pauli Exclusion Principle: No two electrons can have the same set of quantum numbers.
• Hund's Rule: Electrons will fill degenerate orbitals (orbitals with the same energy) singly before pairing up.

Understanding electron configurations helps explain an element's placement in the periodic table and its chemical behavior. For example, Silicon (Si) has the configuration [Ne]3s²3p², which accounts for its four valence electrons and related chemical properties, such as those affecting its ionization energies.