Question

Which of the following metals is the lightest in the periodic table of elements?
A) Lithium
B) Aluminium
C) Titanium
D) Magnesium

Answer 1

In a modern periodic table, the known elements are arranged in the horizontal rows (known as periods) and the vertical columns (known as groups) according to their chemical properties and atomic numbers. When we move from left to right in the periodic table, we will see that the atomic mass and atomic number of elements increase and they become heavier. So, we will see the atomic numbers and placement of the given elements in the periodic table to determine the lightest element among the given elements.

Complete answer:
We know that in a modern periodic table, the known elements are arranged in the horizontal rows (known as periods) and the vertical columns (known as groups). The elements are arranged according to their chemical properties and atomic numbers.
The greater the atomic mass/ atomic number, the heavier the element.
Now, we will look at the modern periodic table:

So, from the above periodic table, we can see that, the atomic number of Lithium (Li) is $3.$
Atomic number of Aluminium is $13.$
Atomic number of Titanium (Ti) is $22.$
Atomic number of Magnesium (Mg) is $12.$
Hence, we can see that the lightest metals from the above given metals is Lithium.

Therefore, Lithium is the lightest element in the periodic table. So, option (A) is correct.

Note:
Metals have certain characteristic physical and chemical properties such as they are ductile, malleable, lustrous, good conductors of electricity and heat. They also have high density and high melting points. Metals react with non-metals to form ionic compounds which have strong forces of attraction.