Any substance that contains only one kind of an atom is known as an element . Hydrogen and oxygen, on the other hand, cannot be decomposed into simpler substances. They are therefore the elementary, or simplest, chemical substances - elements. Each element is represented by a unique symbol. The notation for each element can be found on the periodic table of elements.
Most elements are metals, which are found on the left and toward the bottom of the periodic table.
A handful of nonmetals are clustered in the upper right corner of the periodic table. The semimetals can be found along the dividing line between the metals and the nonmetals. Atoms Elements are made up of atoms , the smallest particle that has any of the properties of the element. John Dalton, in 1803, proposed a modern theory of the atom based on the following assumptions. Matter is made up of atoms that are indivisible and indestructible.