Classification of Elements Chemistry Problem solution:
some Important question and answer of the chemistry classification of elements. On the Basis of the CBSE and SEC exam.
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Modern Periodic Table |
It is a table of elements that contains all elements in the order of increasing atomic number in such a away that the elements having similar physical and chemical properties are kept in one group.
What is group of the periodic table?
The
elements that form a vertical column of periodic table and having similar
physical and chemical properties are known as groups of periodic table.[Note:
There are 9 groups in periodic table]
Write down full form of IUPAC. How elements are classified into groups according to IUPAC system?
Full
form IUPAC is International Union of Pure and Applied Chemistry. According to
IUPAC,each vertical column of elements is taken as group. So elements are
classified into 18 groups i.e. from 'Group- 1' to 'Group-18.
How the groups of element are made in modern periodic table?Write down the name of the group.
In
modern periodic table,element are classified into 9 groups.
They
are IA,IIA,IIIB,IVB,VB,VIIB,IB,IIB, IIIA, IVA, VA, VIA, VIIA and 0. IA to VIIA
and IB to VIIA i.e. combining group A and group there are 7 groups moreover
group VIII and 0 when there are altogether 9 groups.
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What is the periodic of the periodic table?
The
elements that form a horizontal row of periodic table are known as period of
the periodic table.
What do you mean by very short, short, long and very long period of the periodic table?
Periods
1 of the periodic table is called very short period because it contains only
two elements i.e. Hydrogen and Helium. Period 2 and 3 of the periodic table are
called short period because each of them contains 8 elements. Period 4 and 5 of
the periodic are called long period because they contain 18 elements in each of
them. Sixth period of the periodic table is called the very long period because
it contains 32 elements.
Write down any two advantages of periodic table.
i)
It makes the study of the elements short providing the group study of the
elements.
ii)
Properties of different elements can be comparatively studied by the group
comparison of the elements.
What do you mean by the word ''periodic' of the periodic table?
Periodic
means the order of the definite number
of elements in a regular interval.
Write
down the real name of the following elements named by Mendeleev.
i)
Eka- Aluminium ii) Eka-Born iii)
Eka-Silicon iv) Eka-Manganese
i)
Eka-Aluminium is Gallium.
ii)Eka-Boron
is Scandium
iii)
Eka-Silicon is Germanium
iv)
Eka- Manganese is Technetium.
How was elements arranged in old periodic table made by Mendeleev?
Mendeleev
arranged elements in the increasing order of atomic weight from left to right
of the periodic table.
Write
down Mendeleev's periodic law with its meaning.
The
physical and chemical properties of the elements are the periodic function of
their atomic weight. It means if
elements are arranged in the order of their increasing atomic weight, elements
with similar properties are repeated after certain regular interval.
Write down the importance of Mendeleev's periodic table?
The importance of
Mendeleev's periodic table is:
i) Systematic study
of element: It simplified and systematised the study of elements and their
compounds.
ii) Prediction of
new elements: Some elements were not discovered at the time of Mendeleev. While
making table of elements, he left a space for those elements and predicated
that they will be discovered in future. That encouraged the scientist to
discover them later. For example, Gallium and Geranium were not discovered at
that time. Mendeleev gave space in periodic table for each of them and he named
them as Eka- silicon respectively. Later they were discovered according to
Mendeleev's prediction.
iii) Correction of
doubtful atomic weight: Atomic weight of some elements was calculated incorrectly.
Mendeleev helped to correct it with the help of the of the arrangement of
elements in the periodic table.
Name some elements whose atomic weight was corrected by the arrangement of the elements in the Mendeleev's periodic table.
Gold (Au),platinum
(Pt), Aluminium (AI) etc.
Write down the defect of Mendeleev's periodic table?
i) Anomalous
position of hydrogen: Hydrogen is placed with alkali metals in group-I but it
is non-metal and its property is similar to the halogens of group-VII.
ii) Anomalous pair
of elements: Some elements having higher atomic weight precede the elements
with lower atomic weight. For example Ar (Atomic weight 39.9) precedes K
(Atomic weight 39.1). Similarly Co ( Atomic weight 58.9) precedes Ni (Atomic
weight 58.7)
Write down the
defect of Mendeleev's periodic table?
i) Anomalous
position of hydrogen: Hydrogen is placed with alkali metals in group-I but it
is non-metal and its property is similar to the halogens of group-VII.
ii) Anomalous pair
of elements: Some elements having higher atomic weight precede the elements
with lower atomic weight. For example Ar (Atomic weight 39.9) precedes K
(Atomic weight 39.1). Similarly Co ( Atomic weight 58.9) precedes Ni (Atomic
weight 58.7)
iii) Postion of
istotope:If periodic table was made according to the increasing order of atomic
weight then isotope should also have had position in the periodic table.
iv) Some dissimilar
elements were placed together but some similar elements were placed in
different group. For example CU,AG,AU etc. are placed in group I with alkali
metals like Li, Na, k etc. But similar elements like Cu and Hg were placed in
different group i.e.group I and II respectively.
v) Position of
landthanides and actinides: There wasn't any place for landthanides and
actinides.
vi) Position of
elements of group VIII was not clear because nine elements of group VIII were
placed in the form of triad without any justification.
Write down modern periodic law.
The physical and
chemical properties of elements are a periodic function of their atomic number.
Note: Mosley
suggested that atomic number should be the basis of the classification after
his one of the important experiments. He found that when high speed electron
strikes a metal, x-ray produces. The frequency of x-ray depends upon atomic
number of metal. So he suggested that atomic number should be the basis of
classification.
Write down the difference between old periodic table and modern periodic table.
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Mendeleev's Periodic table
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Modern Periodic table
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a) Elements were arranged in the order
of increasing atomic weight.
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a) Elements are arranged in the order
of increasing atomic number.
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b)There is not a fixed position for
the landthanides and actinides.
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It provides a fixed place for the
landthanides and actinides.
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c) There were 7periods and 8 groups of
element.
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c) There are 7periods and 9 groups of
elements.
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d) Position of isotope was not clear.
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d) Isotopes are not taken in the table
because elements are arranged in the order ok increasing atomic number not
according to atomic weight.
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e) In the place of one element there
were two or three elements.
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e) Eelement has its own place in the
periodic table in a series i.e. from 1to 109.
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f) Elements were divided into groups
and periods only.
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f) Elements are divided into groups, periods
and 4 distinct blocks i.e. s,p,d & f blocks.
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