By Z = 3, we mean that the atomic number of the element is 3. Its electronic configuration is 2, 1. Hence, the valency of the element is 1 (since the outermost shell has only one electron). Therefore, the element with Z = 3 is lithium. For more answers visit to website: https://www.tiwariacademy.comRead more
By Z = 3, we mean that the atomic number of the element is 3. Its electronic configuration is 2, 1. Hence, the valency of the element is 1 (since the outermost shell has only one electron). Therefore, the element with Z = 3 is lithium.
Na has atomic number 11, so its electronic configuration is = 2, 8, 1 When it gives away its outermost shell single electron it changes to Na+ =10= 2, 8 The above configuration indicates completely filled K, L shells. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/cRead more
Na has atomic number 11, so its electronic configuration is = 2, 8, 1
When it gives away its outermost shell single electron it changes to Na+ =10= 2, 8
The above configuration indicates completely filled K, L shells.
(i) Atomic number The atomic number of an element is the total number of protons present in the atom of that element. For example, nitrogen has 7 protons in its atom. Thus, the atomic number of nitrogen is 7. (ii) Mass number The mass number of an element is the sum of the number of protons and neutRead more
(i) Atomic number
The atomic number of an element is the total number of protons present in the atom of that element. For example, nitrogen has 7 protons in its atom. Thus, the atomic number of nitrogen is 7.
(ii) Mass number
The mass number of an element is the sum of the number of protons and neutrons present in the atom of that element. For example, the atom of boron has 5 protons and 6 neutrons. So, the mass number of boron is 5 + 6 = 11.
(iii) Isotopes
They are atoms of the same element and have same atomic number but different mass number/atomic mass. For example:
Carbon: ¹²₆𝐶 and ¹⁴₆𝐶
(iv) Isobars
They are atoms of different elements having same mass number but different atomic number.
For example calcium, atomic number 20 and argon, atomic number 18.
The number of electrons in these atoms is different, but the mass number of both these elements is 40. That is, the total number of neutrons is the same in the atoms of this pair of elements.
Two uses of isotopes are as follows:
(i) An isotope of uranium is used as a fuel in nuclear reactors.
(ii) An isotope of cobalt is used in the treatment of cancer.
The rules for writing of the distribution of electrons in various shells for the first eighteen elements are given below: (i) The maximum number of electrons that a shell can accommodate is given by the formula '2n²', where 'n' is the orbit number or energy level index (n = 1, 2, 3...). The maximumRead more
The rules for writing of the distribution of electrons in various shells for the first eighteen elements are given below:
(i) The maximum number of electrons that a shell can accommodate is given by the formula ‘2n²’, where ‘n’ is the orbit number or energy level index (n = 1, 2, 3…).
The maximum number of electrons present in an orbit of n = 1 given by 2n² = 2 × 1² = 2 Similarly, for second orbit, it is 2n² = 2 × 2² = 8 For third orbit, it is 2n² = 2 × 3² = 18 And so on ….. (ii) The outermost orbit can be accommodated by a maximum number of 8 electrons.
(iii) Shells are filled with electrons in a step wise manner i.e., the outer shell is not occupied with electrons unless the inner shells are completely filled with electrons.
The valency of an element is the combining capacity of that element. The valency of an element is determined by the number of valence electrons present in the atom of that element. If the number of valence electrons of the atom of an element is less than or equal to four, then the valency of that elRead more
The valency of an element is the combining capacity of that element. The valency of an element is determined by the number of valence electrons present in the atom of that element. If the number of valence electrons of the atom of an element is less than or equal to four, then the valency of that element is equal to the number of valence electrons. For example, the atom of silicon has four valence electrons. Thus, the valency of silicon is four. On the other hand, if the number of valence electrons of the atom of an element is greater than four, then the valency of that element is obtained by subtracting the number of valence electrons from eight. For example, the atom of oxygen has six valence electrons. Thus, the valency of oxygen is (8 − 6) i.e., two.
If Z = 3, what would be the valency of the element? Also, name the element.
By Z = 3, we mean that the atomic number of the element is 3. Its electronic configuration is 2, 1. Hence, the valency of the element is 1 (since the outermost shell has only one electron). Therefore, the element with Z = 3 is lithium. For more answers visit to website: https://www.tiwariacademy.comRead more
By Z = 3, we mean that the atomic number of the element is 3. Its electronic configuration is 2, 1. Hence, the valency of the element is 1 (since the outermost shell has only one electron). Therefore, the element with Z = 3 is lithium.
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Na⁺ has completely filled K and L shells. Explain.
Na has atomic number 11, so its electronic configuration is = 2, 8, 1 When it gives away its outermost shell single electron it changes to Na+ =10= 2, 8 The above configuration indicates completely filled K, L shells. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/cRead more
Na has atomic number 11, so its electronic configuration is = 2, 8, 1
When it gives away its outermost shell single electron it changes to Na+ =10= 2, 8
The above configuration indicates completely filled K, L shells.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/
Explain with examples: (i) Atomic number, (ii) Mass number, (iii) Isotopes and (iv) Isobars.
(i) Atomic number The atomic number of an element is the total number of protons present in the atom of that element. For example, nitrogen has 7 protons in its atom. Thus, the atomic number of nitrogen is 7. (ii) Mass number The mass number of an element is the sum of the number of protons and neutRead more
(i) Atomic number
The atomic number of an element is the total number of protons present in the atom of that element. For example, nitrogen has 7 protons in its atom. Thus, the atomic number of nitrogen is 7.
(ii) Mass number
The mass number of an element is the sum of the number of protons and neutrons present in the atom of that element. For example, the atom of boron has 5 protons and 6 neutrons. So, the mass number of boron is 5 + 6 = 11.
(iii) Isotopes
They are atoms of the same element and have same atomic number but different mass number/atomic mass. For example:
Carbon: ¹²₆𝐶 and ¹⁴₆𝐶
(iv) Isobars
They are atoms of different elements having same mass number but different atomic number.
For example calcium, atomic number 20 and argon, atomic number 18.
The number of electrons in these atoms is different, but the mass number of both these elements is 40. That is, the total number of neutrons is the same in the atoms of this pair of elements.
Two uses of isotopes are as follows:
(i) An isotope of uranium is used as a fuel in nuclear reactors.
(ii) An isotope of cobalt is used in the treatment of cancer.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/
Summarize the rules for writing of distribution of electrons in various shells for the first eighteen elements.
The rules for writing of the distribution of electrons in various shells for the first eighteen elements are given below: (i) The maximum number of electrons that a shell can accommodate is given by the formula '2n²', where 'n' is the orbit number or energy level index (n = 1, 2, 3...). The maximumRead more
The rules for writing of the distribution of electrons in various shells for the first eighteen elements are given below:
(i) The maximum number of electrons that a shell can accommodate is given by the formula ‘2n²’, where ‘n’ is the orbit number or energy level index (n = 1, 2, 3…).
The maximum number of electrons present in an orbit of n = 1 given by 2n² = 2 × 1² = 2 Similarly, for second orbit, it is 2n² = 2 × 2² = 8 For third orbit, it is 2n² = 2 × 3² = 18 And so on ….. (ii) The outermost orbit can be accommodated by a maximum number of 8 electrons.
(iii) Shells are filled with electrons in a step wise manner i.e., the outer shell is not occupied with electrons unless the inner shells are completely filled with electrons.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/
Define valency by taking examples of silicon and oxygen.
The valency of an element is the combining capacity of that element. The valency of an element is determined by the number of valence electrons present in the atom of that element. If the number of valence electrons of the atom of an element is less than or equal to four, then the valency of that elRead more
The valency of an element is the combining capacity of that element. The valency of an element is determined by the number of valence electrons present in the atom of that element. If the number of valence electrons of the atom of an element is less than or equal to four, then the valency of that element is equal to the number of valence electrons. For example, the atom of silicon has four valence electrons. Thus, the valency of silicon is four. On the other hand, if the number of valence electrons of the atom of an element is greater than four, then the valency of that element is obtained by subtracting the number of valence electrons from eight. For example, the atom of oxygen has six valence electrons. Thus, the valency of oxygen is (8 − 6) i.e., two.
For more answers visit to website:
See lesshttps://www.tiwariacademy.com/ncert-solutions/class-9/science/chapter-4/