An element is a substance whose atoms all have the same number of protons: another way of saying this is that all of a particular element's atoms have the same atomic number.
Elements are chemically the simplest substances and hence cannot be broken down using chemical reactions. Elements can only be changed into other elements using nuclear methods.
Although an element’s atoms must all have the same number of protons, they can have different numbers of neutrons and hence different masses. When atoms of the same element have different numbers of neutrons, they are called isotopes.
The Most Abundant Elements
With only one proton, hydrogen is the simplest, lightest element, followed by helium, which has two protons. Oxygen atoms have eight protons.
At 75 percent, hydrogen is the most abundant element in the universe, followed by helium at 23 percent, then oxygen at 1 percent. All of the other elements make up the remaining 1 percent.
In the earth’s crust, oxygen (47%) is the most abundant element, followed by silicon (28%) and aluminum (8%). Thanks iam happy to hear from you