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Note on Characteristics of a Group

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Characteristics of groups

  1. 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.

    http://i.imgur.com/YQZQGyt.png

  2. 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.
  3. 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.

    http://i.imgur.com/tMuZA2q.png

  4. 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.

    http://i.imgur.com/dA250LA.png

  5. 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

    http://i.imgur.com/cZlLs2Y.gif

  6. 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.
  7. 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.

    http://i.imgur.com/4Yrudj9.gif

  8. 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.

    http://i.imgur.com/qSnpTSJ.gif

  • 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. 
.

Very Short Questions

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.

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:

  1. It can lose one electron like other element of this group in order to combine with other atom.
  2. It shows electropositive character like metals.
Sodium element is more reactive than hydrogen element.

0%
  • The value of valency in a group is ______.

    same for all


    0 for all


    differ in all


    1 for all


  • The atomic radius of the element lying in a group ______.

    may increase or decrease.


    inceases from top to bottom.


    decreases from top to bottom.


    remains same from top to bottom.


  • The elements in each vertical column on the periodic table usually have similar properties and are called a ______.

    group


    property


    periodic table


    period


  • The energy which is required to pull out the most loosely, held electron in an atom is ________.

    metallic character


    ionization energy


    potential energy


    reactivity


  • In a group reactivity from top to bottom _______.

    increases
    may increase or decrease
    decreases
    remains same
  • Which element has the highest first ionization energy?

    aluminium
    sodium
    calcium
    phosphorus
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DISCUSSIONS ABOUT THIS NOTE

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Nrj Nrj

In which group very active metals are kept?


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Bibek

Why the elements of group vA ,, vIA and VIIA less reactive as we go down of the periods ... 0lz ans me fast..


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kaisir dar

what is molecule


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