Chapter 14: Problem 14
Fluorine lies between oxygen and neon in Period \(2 .\) Whereas atomic sizes and ionization energies of these three elements change smoothly, their electronegativities display a dramatic change. What is this change, and how do their electron configurations explain it?
Short Answer
Expert verified
Fluorine has the highest electronegativity, oxygen is less electronegative, and neon has no electronegativity. This is due to their electron configurations and valence electron completion.
Step by step solution
01
- Identify the elements and their positions
Fluorine is located between oxygen and neon in Period 2 of the periodic table.
02
- Understand atomic size and ionization energy trends
Atomic size decreases and ionization energy increases as you move from left to right across Period 2.
03
- Define electronegativity
Electronegativity measures an atom's ability to attract and hold onto electrons.
04
- Examine the electronegativity values
Oxygen has an electronegativity of 3.44, fluorine has the highest at 3.98, and neon is generally considered to have no electronegativity.
05
- Compare electron configurations
Oxygen: 1s² 2s² 2p⁴, Fluorine: 1s² 2s² 2p⁵, Neon: 1s² 2s² 2p⁶. Notice that as you move from oxygen to fluorine, they tend to gain an increasing number of protons and electrons, filling their 2p orbitals.
06
- Explain the dramatic change in electronegativity
Fluorine's almost complete outer shell (2s² 2p⁵) makes it extremely electronegative because it needs just one more electron to fill its valence shell. In contrast, neon has a full valence shell (2s² 2p⁶), making it stable and non-electronegative.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Atomic Size
Atomic size, or atomic radius, refers to the distance from the nucleus of an atom to the outermost electrons. As you move from left to right across Period 2 of the periodic table, atomic size decreases.
This is because electrons are added to the same energy level (shell) while the number of protons in the nucleus increases.
The increased positive charge from the protons pulls the electrons closer to the nucleus, resulting in a smaller atomic radius. For example:
This is because electrons are added to the same energy level (shell) while the number of protons in the nucleus increases.
The increased positive charge from the protons pulls the electrons closer to the nucleus, resulting in a smaller atomic radius. For example:
- Oxygen: 1s² 2s² 2p⁴
- Fluorine: 1s² 2s² 2p⁵
- Neon: 1s² 2s² 2p⁶
Ionization Energy
Ionization energy is the energy required to remove an electron from an atom. As atomic size decreases across Period 2, ionization energy increases.
This happens because the electrons are held more tightly by the nucleus due to increased nuclear charge. Therefore, more energy is needed to remove one of these tightly held electrons. In Period 2:
This happens because the electrons are held more tightly by the nucleus due to increased nuclear charge. Therefore, more energy is needed to remove one of these tightly held electrons. In Period 2:
- Oxygen has a lower ionization energy compared to fluorine.
- Fluorine has a higher ionization energy compared to both oxygen and neon.
- Neon has the highest ionization energy in this group since it has a full outer shell and is very stable.
Electron Configurations
Electron configurations describe how electrons are distributed in an atom's orbitals. This is crucial in understanding elements' chemical properties. For our elements:
- Oxygen: 1s² 2s² 2p⁴
- Fluorine: 1s² 2s² 2p⁵
- Neon: 1s² 2s² 2p⁶
Periodic Table Trends
Periodic table trends help predict various properties of elements, such as atomic size, ionization energy, and electronegativity. Key trends across Period 2 include:
- Decreasing atomic size: Moving left to right, atoms become smaller due to an increase in nuclear charge.
- Increasing ionization energy: Elements require more energy to remove an electron as you go across the period.
- Increasing electronegativity: The tendency of atoms to attract electrons increases, with fluorine being the most electronegative.
Valence Electrons
Valence electrons are the outermost electrons of an atom and play a key role in chemical reactions and bond formation. In Period 2, the valence electrons increase as you move from left to right. Consider the elements:
- Oxygen: 6 valence electrons
- Fluorine: 7 valence electrons
- Neon: 8 valence electrons (a full valence shell)