Question

Identify each statement as true or false: (a) Ionization energies are always negative quantities. (b) Oxygen has a larger first ionization energy than fluorine. (c) The second ionization energy of an atom is always greater than its first ionization energy. (d) The third ionization energy is the energy needed to ionize three electrons from a neutral atom.

Short answer

(a) FALSE: Ionization energies are always positive quantities. (b) FALSE: Oxygen has a smaller first ionization energy than fluorine. (c) TRUE: The second ionization energy of an atom is always greater than its first ionization energy. (d) FALSE: The third ionization energy refers to the energy needed to remove the third electron from an ion with a +2 charge, not the sum of energies required to remove all three electrons.

Step-by-step solution

Statement (a): Ionization energies are always negative quantities.

Ionization energy is the energy needed to remove an electron from an atom or ion. Since energy is required to remove an electron, ionization energies are always positive quantities. Therefore, this statement is FALSE.

Statement (b): Oxygen has a larger first ionization energy than fluorine.

The first ionization energy generally increases from left to right across a period in the periodic table, due to an increasing effective nuclear charge. Oxygen is to the left of fluorine in the periodic table, so it has a weaker effective nuclear charge than fluorine. This means oxygen would generally have a lower ionization energy than fluorine. Therefore, this statement is FALSE.

Statement (c): The second ionization energy of an atom is always greater than its first ionization energy.

The first ionization energy refers to the energy required to remove the first electron from a neutral atom, while the second ionization energy refers to removing an electron from an ion with a +1 charge. Since the positively charged ion has a stronger attraction to the remaining electrons, the energy required to remove a second electron is generally greater than the energy required to remove the first electron. Therefore, this statement is TRUE.

Statement (d): The third ionization energy is the energy needed to ionize three electrons from a neutral atom.

The third ionization energy refers to the energy needed to remove the third electron from an ion with a +2 charge. However, this statement is slightly misleading, as the third ionization energy only refers to the energy needed to remove the third electron, not the sum of the energy needed to remove all three electrons. The third ionization energy does not directly represent the energy needed to remove three electrons; you would need to add the first, second, and third ionization energies together to find the total energy required to remove three electrons. Therefore, this statement is FALSE.

Key concepts

Periodic Table

The periodic table is a tabular arrangement of chemical elements, organized based on their atomic numbers, electron configurations, and recurring chemical properties. It serves as a valuable tool for understanding various trends and properties of elements.
In the periodic table, elements are arranged in rows called periods and columns called groups. As you move from left to right across a period, the atomic number increases, meaning there are more protons in the nucleus and more electrons surrounding it. This increase generally leads to greater ionization energies, especially going through the same period.

• Periods: Rows on the periodic table; moving left to right signifies an increase in atomic number.
• Groups: Columns on the periodic table; elements in the same group often have similar chemical properties.
• Trends: Ionization energy generally increases from left to right across a period and decreases down a group.

Ionization energy, the energy needed to remove an electron from an atom, is closely tied to an element's position on the periodic table. For instance, fluorine is located to the right of oxygen in the periodic table and consequently has a higher ionization energy due to stronger nuclear charge and electron configuration.

Atomic Structure

Atomic structure refers to the composition of an atom, which consists of a nucleus containing protons and neutrons, surrounded by electrons in orbitals. The number of protons determines the atomic number and defines the element.
The distribution of electrons around the nucleus affects the atom's chemical properties and energy levels. Here's how it works:

• Nucleus: Comprised of protons (positively charged) and neutrons (neutral); the center of the atom.
• Electrons: Negatively charged particles that orbit the nucleus, forming electron clouds at various energy levels.
• Orbitals: Regions around the nucleus where electrons are likely found.

Ionization energy is influenced by atomic structure because removing an electron requires energy to overcome the attraction between the negatively charged electron and the positively charged nucleus. As with the second and third ionization energies, pulling electrons from an ion with fewer electrons can be more challenging because the remaining electrons are more strongly attracted by the nucleus.

Electron Configuration

Electron configuration is the distribution of electrons in an atom's orbitals. It follows specific rules and principles that help determine how an atom will interact chemically.
Understanding electron configuration provides insights into ionization energy and reactivity:

• Pauli Exclusion Principle: No two electrons in the same atom can have the same set of quantum numbers, meaning each electron occupies a unique position.
• Aufbau Principle: Electrons fill orbitals starting with the lowest energy level, building up to higher levels.
• Hund’s Rule: Electrons will occupy degenerate orbitals singly before pairing up to minimize electron repulsion.

Ionization energy is higher when electrons are removed from a stable configuration. As seen in the periodic table, removing a first electron from a neutral atom is easier compared to removing a second or third, because once an electron is removed, the ion becomes more stable and positively charged, leading to stronger attraction of the remaining electrons.