Question

Consider the following statements: "The ionization energy for the potassium atom is negative because when K loses an electron to become ${\mathrm{K}}^{+}$, it achieves a noble gas electron configuration." Indicate everything that is correct in this statement. Indicate everything that is incorrect. Correct the mistaken information and explain the error.

Short answer

In the given statement, it is incorrect that the ionization energy for potassium is negative. Ionization energy is always positive. Potassium has an ionization energy of +4.340 eV or +419 kJ/mol. The correct statement should be: "The ionization energy for the potassium atom is positive because when K loses an electron to become $K^{+}$, it achieves a noble gas electron configuration." The rest of the original statement is correct, as potassium does achieve a noble gas electron configuration (argon) after losing an electron.

Step-by-step solution

Understanding Ionization Energy

Ionization energy is defined as the amount of energy required to remove an electron from an atom or ion. In other words, it is the energy needed to overcome the attractive force between the nucleus and an electron in an atom or ion. Generally, ionization energy is expressed in units of electron volts (eV) or kilojoules per mole (kJ/mol).

Understanding Noble Gas Electron Configuration

A noble gas electron configuration refers to the electron configuration of the nearest noble gas element in the periodic table, which is just preceding the element in question. Noble gases have a full electron shell, specifically 8 electrons in their outermost shell (except for helium, which has 2). Atoms and ions with noble gas electron configurations are stable because they have achieved the lowest possible energy state.

Analyzing the Statement

The statement states that the ionization energy for the potassium atom is negative because when potassium loses an electron to become K^{+}, it achieves a noble gas electron configuration. To evaluate the correctness of this statement, we must analyze the ionization energy value and the effect of losing an electron on potassium's electron configuration.

Analyzing Ionization Energy for Potassium

Potassium (K) has an atomic number of 19, and its electron configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$. The ionization energy for potassium is the energy required to remove an electron from the outermost shell (4s); the value is positive (+4.340 eV or +419 kJ/mol). Ionization energy cannot be negative; thus, the statement is incorrect regarding the ionization energy being negative.

Analyzing the Effect on Potassium's Electron Configuration

When potassium loses an electron to become K^{+}, its electron configuration changes to $1s^{2}2s^{2}2p^{6}3s^{2}3p^6$, which is the noble gas electron configuration of argon (Ar). This part of the statement is correct because potassium does achieve a noble gas electron configuration after losing an electron.

Correcting the Statement and Explaining the Error

The corrected statement should be: "The ionization energy for the potassium atom is positive because when K loses an electron to become K^{+}, it achieves a noble gas electron configuration." The erroneous part of the original statement was claiming that the ionization energy is negative. Ionization energy is always positive, as it is the energy required to remove an electron from an atom or ion, overcoming the force of attraction between the nucleus and the electron.

Key concepts

Noble Gas Electron Configuration

The noble gas electron configuration is a highly stable state for an atom. Noble gases, such as helium, neon, and argon, exhibit full outer electron shells which contribute to their inert nature. This means they are less likely to react chemically with other elements.

When an element or ion attains a noble gas electron configuration, it achieves stability by having a complete set of electrons in its valence shell. Most elements strive for this stable, low-energy configuration by either gaining, losing, or sharing electrons. This is a fundamental principle in understanding how chemical reactions occur and how bonds are formed between atoms.

For example, when a potassium atom loses one electron to become a potassium ion $(K^{+})$, its electron configuration changes to match that of the noble gas argon, $1s^{2}2s^{2}2p^{6}3s^{2}3p^6$. This loss of an electron brings about a stable, noble gas-like configuration, making it energetically favorable. This configuration is crucial as it demonstrates the tendency of atoms to reach stable electronic states.

Potassium Atom

The potassium atom is an interesting element found in group 1 of the periodic table. It is classified as an alkali metal. Potassium is characterized by a single electron in its outermost shell, which is the 4s orbital. This configuration is written as $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^1$.

This lone electron in the 4s orbital is relatively easy to remove, which reflects potassium's low ionization energy compared to other elements. The removal of this electron results in the formation of a positively charged ion $(ext{K}^{+})$, and potassium then gains the electron configuration of the noble gas, argon.

Potassium's tendency to lose its 4s electron is a key feature of its chemical reactivity. It reacts easily with nonmetals, particularly halogens, to form ionic compounds. In essence, the characteristics of the potassium atom such as its reactivity, its ionization energy, and its position on the periodic table are interconnected and help predict its behavior in chemical reactions.

Periodic Table

The periodic table is an organized chart of all known chemical elements. It is structured so that elements with similar properties are located in the same columns, called groups. The horizontal rows are known as periods.

Each element is placed in the periodic table according to its atomic number, which is the number of protons in its nucleus. This organization helps predict the type of electron configuration an element will possess, and gives insight into its chemical behavior.

Noble gases are located in Group 18 of the periodic table and are characterized by complete valence electron shells, which contribute to their unreactive nature. The potassium atom, on the other hand, is located in Group 1. This group is comprised of alkali metals, known for being highly reactive.

The position of an element in the periodic table provides valuable information about electron configurations, ionization energies, and chemical reactivity, allowing us to understand and predict both physical and chemical properties of elements. The periodic table is not merely a listing of elements; it reflects the underlying principles govering atomic structure and the laws of chemistry.