Chemistry Review

• The charge on a carbonate ion is -2.
• The charge on a sulfate ion is -2.
• The charge on a nitrate ion is -1.
• The charge on a hydroxide ion is -1.
• The charge on a hydrogen carbonate ion is -1.
• The charge on an ammonium ion is +1.
• A compound consists of two or more elements chemically combined.
• The relative atomic mass is a calculated average of the mass numbers for all the isotopes of that element.
• A molecule is two or more atoms joined together
• The diatomic molecules are hydrogen, oxygen, nitrogen, chlorine, fluorine, bromine and iodine.
• An atom is the smallest part of an element which can take part in a chemical reaction.
• An ion is an atom (or group of atoms) that has lost or gained electrons. Ions are positively or negatively charged.
• An isotope is an element that has a different number of neutrons. E.g. chlorine, atomic number 17, mass number 35 and 37, 18 or 20 electrons respectively.
• A molecule is two or more atoms joined together.
• Ammonium is $NH4^+$
• Acid + metal -> salt + hydrogen
• Acid + oxide -> salt + water
• Acid + hydroxide -> salt + water
• Acid + metal carbonate -> salt + water + carbon dioxide