Question

What is meant by the statement that “the atomic number of sodium is eleven”?

Answer 1

Hint: We know that every element in the periodic table has a definite atomic number. The elements are arranged according to the atomic number.

Complete answer:
We know that in the periodic table the element sodium (Na) is placed in group 1A. It is an alkali metal and has an atomic number of 11.
We also know that in the nucleus of an atom the number of protons is equal to the atomic number, which is denoted by Z. The mass number of the atom is defined as the sum of the number of neutrons and protons in the nucleus.
So, by the statement that “the atomic number of sodium is eleven” we can conclude that, number of protons in sodium is also 11. And as the number of protons and electrons are equal, therefore, the number of electrons in sodium is also 11.

Additional information:
Dimitri Ivanovich Mendeleev on February 17, 1869 has first formulated the modern periodic table. The periodic table contains all the elements known to us. All the elements in the periodic table are grouped according to definite periods and groups. The elements placed in a particular group have similar properties such as chemical properties, reactivity etc. The elements in a group or in a period follow definite trends in size, atomic number etc.

Note:
Students may get confused about how the atomic number is related to the number of protons and the number of electrons. It is important to note that the atomic number is equal to the number of electrons and the number of protons.