Question

Arrange \(\mathrm{Ca}, \mathrm{Se}, \mathrm{F}, \mathrm{S}\), and \(\mathrm{Rb}\) in order of increasing ionization energy.

Short answer

The order of increasing ionization energy for the elements Ca, Se, F, S, and Rb is: \(\mathrm{Rb < Ca < Se < S < F}\).

Step-by-step solution

Understanding Ionization Energy

Ionization energy is the energy required to remove an electron from a gaseous atom or ion. The first ionization energy is the energy needed to remove the first electron from an atom, the second ionization energy is the energy needed for the removal of the second electron, and so on. In general, the ionization energy increases as we move across a period (left to right) in the periodic table and decreases as we move down a group (top to bottom).

Identifying the Position of Each Element

We can locate these elements in the periodic table and identify their positions in terms of periods and groups. This will help us to understand the general trend in ionization energy for these elements. Ca - Calcium - Group 2, Period 4 Se - Selenium - Group 16, Period 4 F - Fluorine - Group 17, Period 2 S - Sulfur - Group 16, Period 3 Rb - Rubidium - Group 1, Period 5

Comparing the Ionization Energies Based on Group Trends

Since ionization energy typically decreases as we move down a group, we can make the following comparisons: Calcium (Ca) and Rubidium (Rb) are both alkaline earth metals (Group 1 and 2 elements). Since Rb is in a lower period (larger atomic size) than Ca, its ionization energy will be lower than that of Ca. Selenium (Se) and Sulfur (S) are in the same group (Group 16). Since Se is in a lower period than S, its ionization energy will be lower than that of S. Fluorine (F) is in Group 17. Due to its high electronegativity and its position in the periodic table, F has the highest ionization energy among the given elements.

Arranging the Elements in Order of Increasing Ionization Energy

Based on our understanding of ionization energy trends and the position of the elements, we can now arrange them in the order of increasing ionization energy: Rubidium (Rb) < Calcium (Ca) < Selenium (Se) < Sulfur (S) < Fluorine (F) Thus, the order of increasing ionization energy for these elements is Rb, Ca, Se, S, and F.

Key concepts

Periodic Table Trends

The periodic table is a comprehensive chart that organizes chemical elements based on their atomic structure and properties. One key property explained by the periodic table is ionization energy, which shows specific trends moving across periods and down groups.

• Across a Period: As we move from left to right across a period, the ionization energy generally increases. This is because atoms are adding protons to their nuclei and electrons to their outermost orbitals, resulting in a greater pull between the positively charged nucleus and negatively charged electrons.
• Down a Group: Conversely, as we move down a group, the ionization energy tends to decrease. Each step down a group adds a new electron shell, increasing the distance between the outermost electrons and the nucleus, and thus, reducing the nuclear charge experienced by those electrons. This makes it easier for an atom to lose an electron.

Considerations of Atomic Radius and Electron Shielding

The size of an atom, known as the atomic radius, also influences the ionization energy. Generally, the larger the atomic radius, the lower the ionization energy due to the greater distance between the nucleus and the outer electron. In addition, the shielding effect, where inner-shell electrons block the pull of the nucleus from the valence electrons, plays a significant role in determining ionization energy.

Atomic Structure

To delve deeper into ionization energy, it's essential to understand the basics of atomic structure. An atom is composed of a central nucleus made of protons and neutrons, surrounded by electrons in orbitals at various energy levels.

• Protons are positively charged particles in the nucleus that determine the atomic number and the element's identity.
• Neutrons are neutral particles that contribute to the nucleus's mass.
• Electrons are negatively charged particles that orbit the nucleus and are responsible for chemical bonding and reactions.

Energy Levels and Electron Configuration

The energy levels or shells are areas where electrons are likely to be found. The closer an energy level is to the nucleus, the lower its energy. Electrons fill these levels in a specific order based on their energy, with those in the outermost shell (valence electrons) being the most reactive. The configuration of these electrons directly impacts the ionization energy as they are the ones to be removed during ionization.

Electronegativity

Electronegativity is another pivotal concept intricately linked to ionization energy. It is a measure of an atom's tendency to attract and bind with electrons during chemical bond formation.

• High Electronegativity: Elements with high electronegativity possess a strong pull on their electrons and electrons in bonds with other atoms. Thus, they tend to have higher ionization energies because removing an electron from such an atom requires more energy.
• Fluorine as an Exemplar: Fluorine, for instance, is the most electronegative element and consequently has a very high ionization energy.

The Relationship with Ionization Energy

There is a direct correlation between electronegativity and ionization energy. As electronegativity increases, so does ionization energy. This is because atoms with high electronegativity create a strong effective nuclear charge, meaning the nucleus can hold onto its electrons more tightly, making the process of ionization require more energy.