Problem 87 - Chemistry The Molecular Science

Question

Which of these groups of elements is arranged correctly in order of increasing ionization energy? (a) \(\mathrm{C}\). \(\mathrm{Si}, \mathrm{Li}, \mathrm{Ne}\) (b) Ne, Si, \(\mathrm{C}, \mathrm{Li}\) (c) Li, Si, \(\mathrm{C}, \mathrm{Ne}\) (d) \(\mathrm{Ne}, \mathrm{C}, \mathrm{Si}, \mathrm{L} \mathrm{i}\)

Step-by-Step Solution

Answer

Option (c) is correct: Li, Si, C, Ne.

Step 1: Understand Ionization Energy Trend

Ionization energy is the energy required to remove an electron from an atom. It generally increases across a period from left to right due to increasing nuclear charge and decreases down a group because electrons are farther from the nucleus in higher energy levels.

Step 2: Arrange Elements According to Periodic Table

List the elements and determine their positions in the periodic table: \( \text{Li}, \text{C}, \text{Si}, \text{Ne} \). Li is in group 1, Ne is in group 18, C is in group 14, and Si is below C in group 14.

Step 3: Analyze Each Option

Consider each option in relation to the ionization energy trend: - (a) \( \text{C}, \text{Si}, \text{Li}, \text{Ne} \) - (b) \( \text{Ne}, \text{Si}, \text{C}, \text{Li} \) - (c) \( \text{Li}, \text{Si}, \text{C}, \text{Ne} \) - (d) \( \text{Ne}, \text{C}, \text{Si}, \text{Li} \)

Step 4: Compare with Known Trends

Recall that Ne has the highest ionization energy, followed by \( \text{C} \), \( \text{Si} \), and \( \text{Li} \). Thus, the correct order from lowest to highest ionization energy is \( \text{Li}, \text{Si}, \text{C}, \text{Ne} \).

Step 5: Verify the Correct Option

Check the alignment of options with the correct order. Option (c) provides this sequence: \( \text{Li}, \text{Si}, \text{C}, \text{Ne} \). Therefore, option (c) is correctly arranged in order of increasing ionization energy.

Key Concepts

Periodic Table

The periodic table is a powerful tool in chemistry, helping us understand the properties of chemical elements. It's organized in such a way that elements with similar properties are grouped together.
As you move across a period, elements show a gradual increase in ionization energy. This is because the atomic number and positive charge of the nucleus increase, which pulls electrons closer to the nucleus.

• Elements are arranged in rows called periods and columns called groups.
• Ionization energy generally increases from left to right across a period.
• Moving down a group, ionization energy decreases because electrons are farther from the nucleus.

Understanding the layout of the periodic table is crucial for predicting and explaining element behavior, such as ionization energy trends.

Chemical Elements

Chemical elements are pure substances consisting of only one type of atom. Each element has a unique number of protons in its nucleus, defined by its atomic number.
For example, hydrogen is element number 1, with one proton, and carbon is number 6, with six protons.

• Elements are represented by unique symbols in the periodic table.
• Each element has a distinct atomic structure, affecting its chemical behavior.
• Elements like neon and lithium show characteristic ionization energies due to their atomic structures.

These properties help chemists understand how elements will interact with others, especially in terms of gaining or losing electrons.

Atomic Structure

The atomic structure of an element plays a key role in determining its physical and chemical properties. Atoms consist of a nucleus containing protons and neutrons, surrounded by electrons in orbitals.
This structure determines how strongly an atom holds onto its electrons, which is related to ionization energy.

• Protons determine the element's identity, as seen in the periodic table.
• Electrons are found in energy levels or shells around the nucleus.
• Ionization energy requires energy to remove an electron from the outer shell.

As you understand more about atomic structure, it becomes easier to predict and rationalize trends like ionization energy, helping to explain why certain groups of elements have higher or lower ionization energy values.