Fundamental Ideas

Atoms, Elements and Compounds

All substances are made up of atoms. Elements are substances made of only one type of atom. Symbols are used to show what happens in chemical reactions. Atoms have a tiny nucleus surrounded by electrons. When elements react, their atoms join with atoms of other elements. Atoms form chemical bonds by losing, gaining or sharing a small number of electrons. Compounds contain the atoms of two or more elements bonded together. Nucleus contains neutrons which are neutral, and protons and electrons which are electrically charged. Protons have a relative charge of +1 and electrons -1. Number of electrons = number of protons, menaing atoms have no overall charge. Atomic number…