Chapter 5: Problem 47
Why do the halogens readily form 1 -ions?
Short Answer
Expert verified
Halogens readily form 1- ions to achieve a stable, full valence shell of eight electrons.
Step by step solution
01
- Identify Halogens
Halogens are elements found in Group 17 of the periodic table. They include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
02
- Understand Electron Configuration
Halogens have seven electrons in their outermost electron shell. Their electron configuration ends in 'ns^2 np^5'.
03
- Octet Rule
Atoms tend to gain, lose, or share electrons to achieve a full valence shell of eight electrons, known as the octet rule. Halogens need one more electron to complete their octet.
04
- Gain One Electron
To achieve a full valence shell, halogens readily gain one electron, which results in a -1 charge.
05
- Stability
By gaining one electron, halogens achieve a stable electron configuration similar to that of noble gases, which is energetically favorable.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Group 17 elements
Group 17 elements, also known as halogens, are positioned in the second last column of the periodic table. This group includes:
- Fluorine (F)
- Chlorine (Cl)
- Bromine (Br)
- Iodine (I)
- Astatine (At)
Electron Configuration
The electron configuration of an atom describes the distribution of electrons in different orbitals around the nucleus. For halogens, their electron configuration ends in 'ns^2 np^5'. This means they have 7 electrons in their outermost shell—2 in the 's' orbital and 5 in the 'p' orbital.
For instance, chlorine's electron configuration is:
For instance, chlorine's electron configuration is:
- 1s² 2s² 2p⁶ 3s² 3p⁵
Octet Rule
The octet rule is a chemical rule of thumb that reflects the observation that atoms of main-group elements tend to combine in such a way that each atom has eight electrons in its valence shell, giving it the same electron configuration as a noble gas. This concept is vital for understanding why atoms bond the way they do.
Halogens, with their seven valence electrons, need only one more electron to complete their octet. This drives them to form 1- ions by gaining an extra electron, aligning their electron configuration with the nearest noble gas. This quest for eight electrons is what defines their high reactivity.
Halogens, with their seven valence electrons, need only one more electron to complete their octet. This drives them to form 1- ions by gaining an extra electron, aligning their electron configuration with the nearest noble gas. This quest for eight electrons is what defines their high reactivity.
Valence Electrons
Valence electrons are the outermost electrons of an atom and are crucial for forming chemical bonds. For the elements in Group 17, they have 7 valence electrons. These electrons determine the chemical behavior of the halogens.
The chemical reactivity and bonding tendencies of halogens stem largely from these 7 valence electrons. Adding one more electron results in a stable, filled valence shell, making halogens particularly prone to forming 1- ions in chemical reactions.
The chemical reactivity and bonding tendencies of halogens stem largely from these 7 valence electrons. Adding one more electron results in a stable, filled valence shell, making halogens particularly prone to forming 1- ions in chemical reactions.
Noble Gas Stability
Noble gases are located in Group 18 of the periodic table and possess a full valence shell. This full valence shell configuration makes them exceptionally stable, almost non-reactive, and energetically favorable.
Halogens, when they gain one electron to form a 1- ion, achieve a stable electron configuration identical to that of noble gases. This stability is why halogens readily gain an extra electron. Achieving this noble gas-like stability by having a complete outer shell is energetically favorable and makes the newly formed halide ions stable and less reactive.
Halogens, when they gain one electron to form a 1- ion, achieve a stable electron configuration identical to that of noble gases. This stability is why halogens readily gain an extra electron. Achieving this noble gas-like stability by having a complete outer shell is energetically favorable and makes the newly formed halide ions stable and less reactive.