Ionic Bonding and Naming

Ionic and Covalent Bonds

• Ionic Bonding
• Forms ionic compounds
• Atoms transfer (gain or lose) electrons
• Ions of opposite charges attract
• Typically between a metal and a non-metal
• ***Ionic lattice: when there is a repeating pattern of positive and negative charged ions
• Covalent Bonding
• Forms covalent compounds
• Atoms share their electrons to complete their valence shells
• Typically between two non-metals
• ***Atoms bound together by sharing electrons are called covalent molecules

Polyatomic and Polyvalent

• - A polyatomic ion is an ion made from more than one type of atom, formed by covalent bonds.
• - How do you use the periodic table of elements? - Look up the element for the number of charges to determine whether it is polyvalent or not. Also: check again after the equation to see if the charge matches the element's potential charges.
• - To find polyatomic ions on the common ion chart, find which ones have more than one type of atom (or capital letter.)
• - Polyatomic: a metal consisting of more than one type of atom. i.e. ClO (2 atoms)
• - Polyvalent: an ion consisting of more than one type of charge. i.e. Copper (Cu) can have a +1 or +2 charge

Counting Atoms

• 
• Caption: To count atoms, write each number for each element before adding.
• How to properly count atoms:
• Identify the number of elements in the compound.
• Count the number of atoms under each element.
• Write the number of atoms down underneath the formula.
• If there are brackets, use the distributive law to count.
• Example:
• Fe2(PO4)2 = 2 + 2 + 8 = 12 atoms

Name to Formula

• 
• How do you write a chemical formula given the name?
• Write down the chemical symbols for the elements to be combined. i.e. Aluminium oxide: Al O
• Note their ion charges. i.e. Al (+3) O (-2)
• For the subscript, if the equation is not balanced: find which number is the "common denominator." i.e. Al (+3 x 2) O (-2 x 3) = Al2 O3. Whatever number you multiply it by is the subscript.

Formula to Name

• 
• How to write a chemical name given the formula:
• First, name the metal ion. i.e. KCl. Potassium.
• Name the nonmetal ion. i.e. KCl. Chlorine.
• Add the suffix to the nonmetal ion "ide" or look at the common ion chart.. i.e. Potassium Chloride

Formula to Name: Polyvalent

• How to write a chemical name for a formula including a polyvalent ion:
• Identify whether it is polyvalent or not, by checking the common ion chart, or the periodic table. If it has more than one charge, it is polyvalent. i.e. Lead (Pb) can have a +2 or +4 charge.
• To find what charge the metal is, use the box method. Draw a small rectangle underneath each element. If it is taken twice/thrice/etc., divide the box accordingly. i.e. PbI2. one box under Pb, two under I2.
• Find the charge of the nonmetal and write that number in the box (or in each section of the box.) i.e. Pb unknown I2 two -1s to make -2.
• Equalize the equation by dividing. i.e. make Pb equal 2 to make it an atom. Pb 2 I2 -1 -1
• Write a Roman Numeral between the two components of the name. The Roman Numeral represents the number that is put in the first box, for example, in lead it is 2.

Side Notes

• The atoms in nonmetals tend to gain electrons because of their need to complete their valence shells, requiring one or two more electrons.
• The subscript to the right of the element symbol represents the relative number of ions in that compound.