Question

Select the member of group \(4 \mathrm{~A}\) that best fits each description: (a) has the lowest first ionization energy, (b) is found in oxidation states ranging from \(-4\) to \(+4\), (c) is most abundant in Earth's crust.

Short answer

(a) Lead (Pb) has the lowest first ionization energy. (b) Carbon (C) is found in oxidation states ranging from -4 to +4. (c) Silicon (Si) is most abundant in Earth's crust.

Step-by-step solution

Identify the element with the lowest first ionization energy

Examine the properties of each Group 4A element, especially the first ionization energies. Recall that, within a group, the ionization energy decreases as we move down the group. Based on this trend, the element with the lowest first ionization energy within group 4A is lead (Pb).

Identify the element with oxidation states ranging from -4 to +4

Consider the number of valence electrons for each Group 4A element - this number corresponds to their most common oxidation state. Carbon has 4 valence electrons and can have oxidation states of positive or negative 4, and every integer value between those extremes. Hence, carbon (C) meets the criteria of having oxidation states ranging from -4 to +4.

Identify the most abundant element in Earth's crust

Examine the distribution of Group 4A elements in Earth's crust by researching percentage composition or consulting a textbook or reputable source. Among Group 4A, silicon (Si) is the most abundant element in Earth's crust, as it makes up approximately 27.7% of the crust's mass. In conclusion, based on the given descriptions: (a) Lead (Pb) has the lowest first ionization energy. (b) Carbon (C) is found in oxidation states ranging from -4 to +4. (c) Silicon (Si) is most abundant in Earth's crust.

Key concepts

First Ionization Energy

Understanding the first ionization energy is crucial for students studying the chemical elements. Ionization energy refers to the amount of energy required to remove the most loosely bound electron from an atom in its gaseous state.
For Group 4A elements, the first ionization energy is an important property, distinguishing how these elements interact and form compounds. It's worth noting that within any group on the periodic table, the ionization energy generally decreases as you move down the group. This is because electrons are further from the nucleus and are less strongly attracted to it, due to the increased shielding effect of inner electrons.
When considering Group 4A elements, lead (Pb) exhibits the lowest first ionization energy. It’s the heaviest and its outer electrons are farthest from the nucleus, hence they are the easiest to remove.

Factors Affecting Ionization Energy

Atomic Size: Larger atoms have lower ionization energies due to the greater distance between the nucleus and the valence electron.
Nuclear Charge: A higher positive charge increases ionization energy as electrons are held more tightly.
Shielding Effect: As the number of filled electron shells increases, the inner electrons shield the valence electron, decreasing the ionization energy.

Oxidation States

The concept of oxidation states is pivotal in understanding the chemistry of Group 4A elements. Oxidation state, also known as oxidation number, describes the degree of oxidation of an atom in a chemical compound, signifying the hypothetical charge that an atom would have if all bonds to atoms of different elements were fully ionic.
Group 4A elements are known to exhibit a variety of oxidation states, typically the most stable being +4, corresponding to their group number. However, carbon (C), the lightest member of the group, is unique in its versatility, presenting oxidation states that range from -4 to +4. This diversity is due to carbon's small size, its ability to form stable covalent bonds, and its presence in a vast array of organic and inorganic compounds.

Oxidation States and Chemical Behavior

• Variability: Carbon's oxidation states allow it to engage in multiple types of chemical reactions.
• Catena Compounds: Carbon can form long chains or rings due to its ability to catenate, leading to an extensive range of organic compounds.
• Heterogeneous Oxidation States: Carbon's multiple oxidation states are central to redox biology and bioenergetics as part of cellular respiration and photosynthesis.

Elemental Abundance in Earth's Crust

The distribution of elements in Earth’s crust is far from uniform, with some elements being vastly more abundant than others. Knowledge of elemental abundance is essential, especially in the field of Earth sciences and environmental sciences.
Within Group 4A, silicon (Si) stands out as the second most abundant element in the Earth’s crust, only surpassed by oxygen. Constituting about 27.7% of the crust's mass, silicon's prevalence is due to its strong ability to bond with oxygen to form the backbone of silicate minerals, which are the most widespread mineral group in the Earth's crust.

Implications of Silicon's Abundance

• Silicate Minerals: Silicon is a primary component of many minerals that make up rocks and soils.
• Industrial Use: Silicon's abundance makes it readily available for use in technology, particularly in semiconductors and solar panels.
• Biological Significance: Though not as biologically critical as carbon, silicon still plays a role in the structure of some marine organisms.