A molecule is when two non-metals share electrons to form stable compounds.
Writing covalent compound formula
- In order to name compounds you use prefixes which are used to count atoms - You can use prefixes for both the non-metals but DO NOT use mono for the first one - Ex. Dinitrogen trioxide - The second non-metal always ends with an 'ide'
Ionic- Made by a metal and a non-metal
Ionic Compound
Ionic Compounds are made by a metal and a non-metal. Metals lose their electrons to the non-metal
Writing ionic compound formula
- Write the element symbol of the metal first, then the non-metal - write the ionic charge for each element - Criss-cross the charges so the charge of the metal goes at the bottom of the non-metal and the charge of the non-metal goes at the bottom of the metal and they become subscripts - remove the '+' and '-' signs as well as all ones '1' - If possible reduce the numbers - When writing the compound name change the ending of the non-metal to 'ide'
Check the metal because metals often have two cations. To know what charges a metal has you can refer to your transition chart. Whatever the metals charge is you write that using roman numerals in a bracket, but first write the element symbol. Ex. Hg(II) Br. The non-metal always ends with an 'ide'. Ex. Mercury(II) bromide
If you see two capitals letters together in an ion then you know its a polyatomic ion. Another way to know it's a polyatomic ion you can look at ending and if it ends with an 'ate' then its a polyatomic.
Writing the polyatomic ion formula
- Start off by writing the element symbol of the metal then the non-metal - Look at the polyatomic chart to see how the non-metal is written - Write the charges of both the metal and the non-metal beside the element - Criss-cross the charges to make them subscripts, so the charge of the metal will go to the non-metal and the charge of the non-metal will go to the metal - Write the polyatomic in a bracket - Ex. Fe(NO3)2 - The non-metal mostly ends with 'ate'
