Characteristics of a Group
Characteristics of groups
- Valence electrons: The number of valence electrons lying in-group is always same i.e. the elements lying in group IA has one valence electron whereas the elements of group VII A have 7 valence electrons.
- Valency: The combining capacity of the elements (i.e. valency) lying in a group is always same. Example: valency of group IA elements is +1 whereas the valency of group VII A elements is -1.
- Atomic size: The atomic radius of the element (i.e. atomic size) lying in a group increases as we go up from top to bottom in a group. It is so because on going down in a group the number of shells successively increases.
- Ionization energy: The energy, which is required to pull out the most loosely, held electron in an atom is called ionization energy. In a group, on going from top to bottom, the ionization energy decreases as the nucleus apply only less energy to pull outer electron because of longer atomic radius.
- Metallic character: The metallic character of the elements lying in a group increases on going from top to bottom in a group. For e.g.: in-group VA the first element is nitrogen, a non-metal and the last element is bismuth, a metal.
|Element ||Atomic Number ||Characters|
|Nitrogen (N) ||7 ||Non Metal|
|Phosphorous (P) ||15 ||Non Metal|
|Arsenic (As) ||33 ||Metalloid|
|Antimony (Sb) ||51 ||Metalloid|
|Bismuth ||83 ||Metal|
- Electro-positivity: After losing their outer electron, an atom becomes electro-positively charged. So in a group, the electro-positivity of the element increases on going from top to bottom as they can lose their outer electron easily because of longer radius.
- Electro-negativity: After gaining its electron, an atom becomes electro-negative. So, the electron gaining capacity of an atom decreases along with the increase in its atomic size. So, electro-negativity of an element decreases as we go from top to bottom.
- Reactivity: In group IA,II A and III A, the elements have the tendency to lose electrons. Therefore, the electron losing capacity increases because of longer atomic radius as we go from up to down. Therefore, reactivity increases on going from top to bottom. But in group VA,VIA and VII A, the elements have the tendency to gain electrons. So, the electron gaining capacity reduces along with the increase in atomic size. So, in these groups, the reactivity decreases as we go from top to bottom.
Things to remember
- Valence electrons, valency, atomic size, ionization energy, metallic character, electron-positivity, electron-negativity and reactivity are the characteristics of groups.
- The atomic radius of the element (i.e. atomic size) lying in a group increases as we go up from top to bottom in a group.
- The energy, which is required to pull out the most loosely, held electron in an atom is called ionization energy.
- After losing their outer electron, an atom becomes electro-positively charged.
- After gaining its electron, an atom becomes electro-negative.
- It includes every relationship which established among the people.
- There can be more than one community in a society. Community smaller than society.
- It is a network of social relationships which cannot see or touched.
- common interests and common objectives are not necessary for society.
Videos for Characteristics of a Group
Chemistry Periodicity in properties
Groups of the Periodic Table
Other Periodic Table Trends
Periodic Table Trends: Ionization Energy
Properties Of Groups On The Periodic Table
The Periodic Table and Group Properties
Questions and Answers
The elements given in the table belong to VIIA. The reactivity of element decreases from top to the bottom due to increase in size of the atoms.
The name of the element is potassium.
Argon is an inert gas because it doesn't take part in chemical reaction due to octet state as it has already eight electrons in its outermost orbit.
Chlorine is an active non-metal because it has 7 electrons in its outermost orbit and has tendency to gain one electron from other atom during chemical reaction for the stability.
The two reasons of placing hydrogen are as follows:
- It can lose one electron like other element of this group in order to combine with other atom.
- It shows electropositive character like metals.
Sodium element is more reactive than hydrogen element.