Wednesday, January 20, 2010

Jan 19th and 20th--naming ionic and covalent compounds

Today in class we went over some rules for naming compounds--then we named some.

The notes from today's class are below:

Tell me (in your notebook) as much as possible about the following chemical formula. Ba(NO3)2

(how many atoms of each element, how do you think it bonds, could you draw the structure?)

Follow-up question. If the formula breaks up into its ions, what are the charges of the Ba and the NO3?


Naming Covalent compounds.

Copy the prefixes on page 31(mono, di, tri, etc)
Put the element symbols in the order they are in the periodic table -but-

Hydrogen would fit between nitrogen and oxygen.

Use the prefixes to name them - but you usually don't use a prefix for the first element in the formula. The prefixes tell you how many atoms of each there are.

drop the 'a' and 'o' from the prefix when attaching the prefix to oxide. Ex CO is carbon monoxide

Naming Ionic Compounds

• The positive element (the metal) goes first.

• The positive one gets to keep its name.

• The negative one gets ide attached to the root of the name.

• (think sodium chloride)

To find out how many of each ion to use, first figure out the charge of each ion (see chapter one)

Then criss-cross the charge numbers.

Example: figure out the formula for a substance made from magnesium and chlorine

Mg, the charge is +2, Cl the charge is -1

Flip flop the charges and the formula is MgCl2

Determine if ionic or covalent, then write the formula for these compounds.
sulfur trioxide

calcium fluoride

phosphorus pentachloride

dinitrogen trioxide

lithium oxide

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