Question

Consider the following statement: "The ionization energy for the potassium atom is negative, because when $\mathrm{K}$ 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 incorrect information, and explain.

Short answer

The ionization energy for the potassium atom is positive, because the energy is required to remove an electron from K to form K+, and this process leads to a noble gas electron configuration. The original statement incorrectly claims that the ionization energy is negative; in reality, ionization energy is always positive since it requires energy input to remove the electron.

Step-by-step solution

Part 1: "The ionization energy for the potassium atom is negative"

The ionization energy is defined as the energy required to remove an electron from an atom in its gaseous state. In the case of potassium (K), this means removing one electron from the outermost shell to form a positive ion (K+). Ionization energy is always a positive value since it requires energy input to remove the electron. Therefore, this part of the statement is incorrect.

Part 2: "because when K loses an electron to become K+..."

When potassium loses an electron, it does indeed become a potassium ion (K+). This part of the statement is correct.

Part 3: "...it achieves a noble gas electron configuration."

When potassium (K) loses an electron, its electron configuration becomes that of the previous noble gas, which is Argon (Ar). This part of the statement is correct. To correct the incorrect part of the statement and explain:

Corrected Statement:

The ionization energy for the potassium atom is positive, because the energy is required to remove an electron from K to form K+, and this process leads to a noble gas electron configuration.

Key concepts

Potassium Atom

Potassium is a fascinating element with the chemical symbol K. This symbol comes from its Latin name, Kalium. Found in Group 1 of the periodic table, it's categorized as an alkali metal. Potassium is highly reactive, particularly with water, which is why you won't find it freely occurring in nature. This element is essential to both plant and human life, playing crucial roles in biological processes.
In terms of its atomic composition, potassium has an atomic number of 19. This means a neutral potassium atom contains 19 protons and 19 electrons. These electrons are distributed across different shells around the nucleus, with one electron being in the outermost shell. This outer electron plays a key role in the chemical reactivity of potassium.
Ionization is an important concept to understand with potassium. This involves removing an electron from an atom, which in the case of a potassium atom, requires energy. This energy is known as the ionization energy, and contrary to the original incorrect statement, it is always positive.

Electron Configuration

Electron configuration is a way to describe the arrangement of electrons around an atom's nucleus. For potassium, with atomic number 19, the full electron configuration is quite detailed. It starts with a series of filled energy levels and sublevels:

• 1s²
• 2s²
• 2p⁶
• 3s²
• 3p⁶
• 4s¹

This sequence shows how electrons fill the lower energy levels first, following the Aufbau principle.
You might be wondering why the electrons fill in this specific order. This is determined by their energy states, with electrons always trying to occupy the lowest possible energy state. Each letter and number combination tells us the number of electrons in a given sublevel as well as the type of orbital (s, p, d, etc.). Here, the outermost electron is in the 4s orbital, which makes it relatively easier to remove during ionization.

Noble Gas Configuration

A noble gas configuration means that an atom has a stable electron arrangement similar to one of the noble gases. The noble gases, found in the last column of the periodic table, are known for their unreactive nature due to their full outer electron shells.
When potassium loses its outermost 4s electron to become a K⁺ ion, its remaining electron configuration mimics that of argon, the noble gas with 18 electrons:

• 1s²
• 2s²
• 2p⁶
• 3s²
• 3p⁶

With this configuration, potassium achieves stability similar to argon, reflecting why atoms tend to form ions. This is the key reason why ionization leads to more stable electronic structures. Potassium, in losing one electron, transitions from a reactive state to a more stable, inert state similar to Argon.