CLASS 9
Lesson structure of atom
Q1)
The total number of electrons in Nitrogen is 7. What is its valency?
Q2)
What name is given to the pair of atoms 7N14 and 7Na15
?
Q3)
What happens to element ‘Z’ if it gains three electrons?
Q4)
Helium has 2 electrons in its valence shell but its valency is not 2. Explain
Q5)
What is the difference between Na and Na+ in terms of number of
electrons?
Q6)
What is a formula of the compound when ‘X’ with atomic number 12 combines with
an element with atomic number 17?
Q7)
Will 35Cl and 37Cl have different valencies? Justify your
answer.
Q8)
One electron is present in the outer most shell of the atom shell of the atom
of an element X. What would be the nature and value of charge on the ion formed
if this electron is removed from the outer most shell?
Q9)
In the atom of an element X, 6 electrons are present in the outermost shell. If
it acquires noble gas configuration by accepting requisite number of electrons,
then what would be the charge on the ion so formed?
Q10) Write the electronic configuration of any
one pair of isotopes and isobars.
Q11)
An atom of an element has two electrons in outermost ‘M’ shell, state
i)
Electronic configuration
ii)
Atomic number
iii)
Number of protons
iv)
Valency of this element
Q12)
From the symbol 18Ar40, write down the number of neutrons
in the nucleus of an atom
Q13)
The sub atomic particles of the atom of two elements ‘A’ and ‘B’ are given
below. Study it and answer the following question. Give justification for your
answer.
|
Element
|
Protons
|
Electrons
|
Neutrons
|
|
A
|
2
|
2
|
2
|
|
B
|
11
|
11
|
12
|
i)
Which of the two is bigger in size?
ii)
Which of the two has more nuclear charge?
iii)
Explain the nature of elements A and B i.e., which of them is
metal and which of them is non-metal?
Q14)
i)
An ion M2+ contains 10 electrons and 12 neutrons.
What is the atomic number and mass number of element M?
ii)
Is it possible for an atom to have 12 protons and 13
electrons? Explain
iii)
Why is helium gas inert.
Q15)
i)
Why are cations smaller than neutral atoms?
ii)
Which has large size Na and K and why? [ Atomic no. of Na =
11, K=19]
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