elements

• An element is a substance made of only one type of atom.
• There are 92 naturally occurring elements, including gold, oxygen, and nitrogen.
• An element can chemically combine with other elements to form compounds.
• There are two types of compounds: covalent and ionic.
• An ion is an atom or molecule that has gained or lost one or more electrons.
• Atoms are made of protons, neutrons, and electrons.
• Metal ions are positive and non-metal ions are negative.
• The charge of a metal ion can be predicted based on the charge of the ion and the charge of the element.
• Chemical reactions can be balanced by ensuring that the same number of each type of atom is on either side of the equation.