1. Atoms and Molecules: Elements are substances consisting of one type of atom. Molecule is a group of two or more atoms that form the smallest identifiable unit into which a pure substance can be divided and still retain the composition and chemical properties of that substance.
2. Isotopes.Isotopes are variants of a particular chemical element which differ in neutron number, and consequently in nucleon number.
3. Subatomic Particles: Protons, Neutrons, Electrons. The atomic number or proton number is the number of protons present in an atom.Electrons have a negative charge that is equal in magnitude to the positive charge of the protons.The neutrons in an element determine the isotope of an atom
4. Electron Configurations.electron configuration indicates the way in which electrons are structured, communicated or organized in an atom according to the electronic shell model
5. Separating and purifying substances: separation of a substance into its components and the removal of impurities. There are a large number of important applications in fields such as medicine and manufacturing.
6. Mixtures and Compound. A mixture, When salt is added to water to make saltwater, it becomes a mixture. The salt and water molecules do not combine to form new molecules, but only “mix” together while still retaining their identities. Compound are formed of molecules of the same sort. The elements can be combined into about 2 million different compounds.
7. Changes in physical state: solid, liquid, gas, plasma. We look at five states of matter on the site. Solids, liquids, gases, plasmas,Solids are often hard, liquids fill containers, and gases surround us in the air.
