1. Learn
  2. Quick Notes
  3. List
  4. Elements in Group 17
Back

Elements in Group 17

 
4.5  Elements in Group 17
 
This image shows a diagram of elements in Group 17 of the periodic table, arranged in a flower-like pattern. Each petal represents an element: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At), and Tennessine (Ts). The center of the flower has a circle labeled ‘ELEMENTS IN GROUP 17.’ The petals are shades of blue, and the Pandai logo is at the bottom right corner.
 
Elements in Group 17
  • Also known as halogen.
  • Very reactive elements.
  • Can be found in the right column of the periodic table as below:

This is an image of the periodic table of elements. The table is color-coded, with some elements highlighted in different colors. The table is arranged in rows and columns, with each element represented by its chemical symbol. The elements are arranged in order of increasing atomic number from left to right and top to bottom. The first column on the left contains elements such as Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). The last column on the right contains elements such as Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn), and Oganesson (Og)
 
Uses of Group 17 Elements
  • Chlorine in bleach.
  • Bromine as a substance in fire extinguishers.
  • Iodine as a disinfectants
 
Physical Properties of Group 17 Elemets
  • Non-metals
  • Does not conduct heat and electricity.
 
Changes in Physical Properties of Elements When Going Down Group 17
  • The atomic radius increases.  
  • Reactivity decreases.
  • Boiling and melting point increases.
  • The van der Waals force increases as the size of the atom increases.
  • The electronegativity decreases because the radius increases and the force between the valence electron and nucleus decreases.
 
Chemical Properties of Group 17 Elements
React with Water to Produce Acids

 

Element Reaction with Water
Cl \(Cl_2(g) + H_2O(l) \rightarrow HCl(aq) + HOCl(aq)\)
Br \(Br_2(l) + H_2O(l) \rightarrow HBr(aq) + HOBr(aq)\)
I \(I_2(s) + H_2O(l) \rightarrow HI(aq) + HOI(aq)\)

 
React with Metal to Produce Metal Halides

 

Element Reaction with Iron
Cl \(3Cl_2(g) +2Fe(s) \rightarrow 2FeCl_3(s)\)
Br \(3Br_2(l) +2Fe(s) \rightarrow 2FeBr_3(s)\)
I \(3I_2(s) +2Fe(s) \rightarrow 2FeI_3(s)\)

 
React with Sodium Hydroxide to Produce Salts and Water

 

Element Reaction with Sodium Hydroxide
Cl \(Cl_2(aq) +2NaOH(aq) \rightarrow NaCl(aq) + NaOCl(aq) + H_2O(l)\)
Br \(Br_2(l) +2NaOH(aq) \rightarrow NaBr(aq) + NaOBr(aq) + H_2O(l)\)
I \(I_2(s) +2NaOH(aq) \rightarrow NaI(aq) + NaOI(aq) + H_2O(l)\)

 
 
Reactivity of Group 17 Elements
  • Group 17 is very reactive, but the reactivity decreases down the group.
  • The elements will accept an electron to achieve a stable octet electron arrangement.
  • The forces between the nucleus and the valence electron become weaker as going down the group. 
Element \(\Downarrow\) As Going Down the Group
F
The atomic radius increases.
\(\downarrow\)
The attractive forces between the nucleus and the valence electrons become weaker.
\(\downarrow\)
More difficult to receive or attract an electron to complete the valence shell.
\(\downarrow\)
Reactivity decreases.
Cl
Br
I
 

 

 


 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.

Elements in Group 17

 
4.5  Elements in Group 17
 
This image shows a diagram of elements in Group 17 of the periodic table, arranged in a flower-like pattern. Each petal represents an element: Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), Astatine (At), and Tennessine (Ts). The center of the flower has a circle labeled ‘ELEMENTS IN GROUP 17.’ The petals are shades of blue, and the Pandai logo is at the bottom right corner.
 
Elements in Group 17
  • Also known as halogen.
  • Very reactive elements.
  • Can be found in the right column of the periodic table as below:

This is an image of the periodic table of elements. The table is color-coded, with some elements highlighted in different colors. The table is arranged in rows and columns, with each element represented by its chemical symbol. The elements are arranged in order of increasing atomic number from left to right and top to bottom. The first column on the left contains elements such as Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). The last column on the right contains elements such as Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn), and Oganesson (Og)
 
Uses of Group 17 Elements
  • Chlorine in bleach.
  • Bromine as a substance in fire extinguishers.
  • Iodine as a disinfectants
 
Physical Properties of Group 17 Elemets
  • Non-metals
  • Does not conduct heat and electricity.
 
Changes in Physical Properties of Elements When Going Down Group 17
  • The atomic radius increases.  
  • Reactivity decreases.
  • Boiling and melting point increases.
  • The van der Waals force increases as the size of the atom increases.
  • The electronegativity decreases because the radius increases and the force between the valence electron and nucleus decreases.
 
Chemical Properties of Group 17 Elements
React with Water to Produce Acids

 

Element Reaction with Water
Cl \(Cl_2(g) + H_2O(l) \rightarrow HCl(aq) + HOCl(aq)\)
Br \(Br_2(l) + H_2O(l) \rightarrow HBr(aq) + HOBr(aq)\)
I \(I_2(s) + H_2O(l) \rightarrow HI(aq) + HOI(aq)\)

 
React with Metal to Produce Metal Halides

 

Element Reaction with Iron
Cl \(3Cl_2(g) +2Fe(s) \rightarrow 2FeCl_3(s)\)
Br \(3Br_2(l) +2Fe(s) \rightarrow 2FeBr_3(s)\)
I \(3I_2(s) +2Fe(s) \rightarrow 2FeI_3(s)\)

 
React with Sodium Hydroxide to Produce Salts and Water

 

Element Reaction with Sodium Hydroxide
Cl \(Cl_2(aq) +2NaOH(aq) \rightarrow NaCl(aq) + NaOCl(aq) + H_2O(l)\)
Br \(Br_2(l) +2NaOH(aq) \rightarrow NaBr(aq) + NaOBr(aq) + H_2O(l)\)
I \(I_2(s) +2NaOH(aq) \rightarrow NaI(aq) + NaOI(aq) + H_2O(l)\)

 
 
Reactivity of Group 17 Elements
  • Group 17 is very reactive, but the reactivity decreases down the group.
  • The elements will accept an electron to achieve a stable octet electron arrangement.
  • The forces between the nucleus and the valence electron become weaker as going down the group. 
Element \(\Downarrow\) As Going Down the Group
F
The atomic radius increases.
\(\downarrow\)
The attractive forces between the nucleus and the valence electrons become weaker.
\(\downarrow\)
More difficult to receive or attract an electron to complete the valence shell.
\(\downarrow\)
Reactivity decreases.
Cl
Br
I
 

 

 


 

The views expressed in the notes here are those of the contributor and don’t necessarily represent the views of Pandai.
Chapter : Periodic Table of Elements
Topic : Elements in Group 17
Form 4 Chemistry
Related notes

Report this note
Timed Exam

Prepare exams with mock exam papers

Learn more
Register for a free Pandai account now
© 2025 Pandai.org All Rights Reserved

Quiz
View video m
Notes
Account