Question

Give the proper definition of : -

• Valency

• Elements

• Atomic Number

• Mass Number

• Isotopes

• Isobars ​

Answer 1

Answer:

(i) Atomic number: The atomic number is the total number of protons present in the atom. For example, the atomic number of sodium is 11. It contains 11 protons and 11 electrons. 

(ii) Mass number: It is the sum of the number of neutrons and the number of protons. For example, the atomic number of magnesium is 12 which is equal to the number of protons, the number of neutrons of magnesium is 12. The mass number is equal to 24 (12+12).

(iii) Isotopes are the elements having same atomic number but different mass number. They have same chemical properties as the number of valence electrons are same. For example, 6C12, 6C13, 6C14 are the three isotopes of carbon. They have same atomic number but different mass number due to difference in the number of neutrons.

(iv) Isobars: They are elements having the same mass number but different atomic number. For example. 18Ar40, 19K40 are isobars having the same atomic mass but different atomic number.

The two uses of isotopes are:

Nuclear weapons and nuclear power require large quantities of isotopes of uranium.

An isotope of cobalt is used in the treatment of cancer.

Answer 2

Answer:

⭕Valency : the valence or valency of an element is the measure of its combining capacity with other atoms when it forms chemical compounds or molecules.

⭕Elements:Chemical element, also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed.

⭕Atomic number: number, the number of a chemical element in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus. ... Accordingly, the number of protons, which is always equal to the number of electrons in the neutral atom, is also the atomic number

⭕Mass Number : number, in nuclear physics, the sum of the numbers of protons and neutrons present in the nucleus of an atom.

⭕Isotope : The atoms of the element whose position in the periodic table are the same and have the same atomic number but different atomic mass are called isotopes.

Isobars are atoms (nuclides) of different chemical elements. ...

⭕ Isobars: Atoms of different elements with different atomic numbers, which have the same mass number, are known as isobars. Isotopes have the same number of protons so their atomic numbers and chemical properties are the same.