Question

Elements are made up of atoms. But why we say elements are indivisible?.
Accoriding to dalton's theory atoms are the smallest unit of matter

Answer 1

You are actually misunderstanding the concept. Elements are just a designation give to an atom or a group of atoms having the same number of protons and neutrons. Elements are themself atoms thats why they are called indivisible. Though the elements are actually atoms they are consist of electrons, protons and neutrons which are the elementary particles or the main constitution of atoms. Element are just a name. For example a Hydrogen atom or a group of hydrogen atoms are collectively given a name Hydrogen and called element because they have same number of protons and electrons in their atoms.