The nucleus, that dense central core of the atom, contains both protons and neutrons. Electrons are outside the nucleus in energy levels. Protons have a positive charge,neutrons have no charge, and electrons have a negative charge. A neutral atom contains equal numbers of protons and electrons.
Elements in the periodic table are either metals, non-metals or metalloids.
Metals are elements that react by losing electron(s) to attain an octet configuration. They occupy groups I, II and III of the periodic table and the transition metals.
Non-metals, on the other hand, are elements that react by gaining electron(s) to attain a stable configuration. Examples include halogens and noble gases among others.
Metalloids are elements in the periodic table that have the properties of both metals and non-metals.
Other examples of metalloids are arsenic, tellurium, germanium and polonium.
