Ions

Ions Charged particles Atoms that have more or less electrons than protons Ions try to imitate the nearest stable element

Ions Elements that have a full valence shell do not form ions Ne

Ions Elements that have one, two, or three valence electrons tend to lose electrons to become stable If an atom loses electrons (which are negative), there are more protons. This means that the atom becomes positive.

Ions Li protons = +3 electrons = -3 e e net charge = 0

Ions +1 Li protons = +3 electrons = -2 e e net charge = +1

Ions Elements that have five, six, or seven valence electrons try to gain electrons to become stable If an atom gains electrons (which are negative), there are fewer protons. So the atom becomes negative.

Ions F e protons = +9 electrons = -9 e e net charge = 0

Ions F e protons = +9 electrons = -10 e e e e e net charge = -1 e e e

Writing Ions First write the symbol. Then write the charge at the top right of the symbol. Example: Li+ O2- The charge on the ion corresponds to the number of electrons gained or lost. Aluminum loses 3 electrons. Therefore, its charge is a positive 3: Al3+

Writing Ions First write the symbol. Then write the charge at the top right of the symbol. Example: Li+ O2-

Superscript This is the number written toward the top of a chemical symbol to indicate what the oxidation number (charge) on that atom is. When there is no superscript, we assume the charge is zero. -1 Cl

Write the correct ion for these elements… Mg+2 Br -1 B+3 O-2 K+1 Element Mg Br B O K

Ion Charges The oxidation number (charge) can be found by just looking at the periodic table. +1 +2 +3 -3 -2 -1 +/- 4

Polyatomic Ions A group of atoms that are chemically bonded and that act like one atom Each polyatomic ion has an electric charge associated with it. Examples: SO 4 -3 HCO 3 OH Sulfate Bicarbonate Hydroxide