An atom is the smallest particle that makes up all matter
Atomic structure is the positively charged nucleus and the negatively charged electrons circling around it, within an atom.
Atoms make up all matter around us, they are the smallest part of all things. Atoms in the periodic table all have different numbers of protons and are known as elements and they can be combined to make compounds and molecules
Bonding describes how metallic and non metallic elements of the periodic table exist as elements or combined together to form new compounds with different properties.
Metallic bonding is the bonding found in metals, positive metal ions surrounded by a sea of delocalized electrons.
Covalent bonding is the bonding found in non metals, involving the sharing of a pair of electrons or more between the atoms.
Our understanding of the atom and nucleus and electrons that surrounds it has come a long way since Ancient Greek times to our understanding of today. With this understanding there have been big leaps in technology and theories that have disproved other theories leading to the model we have today.