The Electrical Properties of Matter

Charged Subatomic Particles Protons – Positive Charge Electrons – Negative Charge Neutrons – No Charge

Atoms Atoms always have a net zero charge. The number of protons is equal to the number of electrons.

Ions Ions occur when an atom gains or loses an electron and gets a charge. A anion is an ion with a negative charge More electrons than protons A cation is an ion with a positive charge More protons than electrons A group of bonded atoms that has a charge is called a polyatomic ion.

Ion Interactions Unlike charges attract each other Positive and negative charges will stick together. Like charges repel each other. Two negative charges repel each other. Two positive charges repel each other.

Ionic Compounds Ionic compounds are formed when positive and negative ions are attracted to each other. Ionic compounds have a net charge of 0.

Formation of Ionic Compounds Ions form compounds with no charge. Example: H+ and S-2 S-2 has a negative two charge. Needs 2 H+ to have no charge. Formula = H2S Example: Al+3 and O-2 The only way to even out the charges is 2Al+3 and 3O-2. Formula: Al2O3

Advanced Ionic Naming The positive charged ion comes first and keeps the name of the element. The negatively charged ion comes second. The ending of the name is changed to –ide Na3As = Sodium arsenide AlN = Aluminum nitride

Advanced Chemical Formulas Periodic Table Labels A periodic table can be used to determine the charge on an ion.

Stock System of Naming Some metals have more than one charge. Examples: Mercury can have a charge of +1 or +4 Iron can have a charge of +2 or +3 In ionic naming, these metals have a Roman numeral after their name to tell the positive charge.

Roman Numerals One = I Two = II Three = III Four = IV Five = V Six = VI Seven = VII Eight = VIII Nine = IV Ten = X

Advanced Formula Practice Manganese (II) iodide The charge is +2 on the manganese (Mn+2) Iodide = iodine with a -1 charge. (I-1) Mn+2I-1 (Cross charges to get the subscripts) MnI2

Advanced Formula Practice Mercury (IV) silicide Mercury has a charge of +4 (Hg+4) Silicide = silicon with a charge of -4 (Si-4) Hg+4Si-4 (Since the charges are the same number, you can just write the symbols together) HgSi