How+to+Classify+Atoms+and+Ions

=​​ How to Classify Atoms and Ions = =page 67-68= =​ definition​：= = - Atoms: the smallest unit of an element which retains the fundamental properties of the element. ex. Na, He, Li = = - Ion: an atom or molecule which possesses an electrical charge. = = ex. Na +, O 2 - = = - Anion: an ion has NEGATIVE charge, then it is called anion. = = ex. O 2 - ，C 2 - = = - Cation: An ion with POSITIVE charge, then it is called cation. = = ex. Li +, Cu 2 + = = - Monatomic: monatomic is the species that make up of ONLY one atom. = = ex. Li, Ar,N 3 - = = - Diatomic: diatomic is the species that make up of two atoms.(the type of atom can be different or same) ex. O 2, ClO - , NaCl = = - Triatomic: triatomic is the species that make up of three atoms. = = ex. H 2 O, O 3, NO 2 = = - Polyatomic: polyatomic is the species that make up of more than one atom. = = ex. MnO 4, CrO 4 2- , NH 4 + = = = = = = = = = = = = Metals can form positive ions = = Nonmentals can form negative ions = = = = example: = = NaCl, Na is metal and Cl is nonmetal, this compound is formed by Na + and Cl - = = CO 2, C and O are nonmentals, this compound is formed by C 2- and O 2-. = = = = = = = = = = = = = =​Every time, when we look at a compound, first count how many atoms do the compound has.= =If there is a particle in the commpound, then this is monatomic specie.= =If there are two particles in the compound, then this is diatomic specie.= =If there are three particle in the coumpound, then this is triatomic specie.= =If there are more than one Particle in the compound, then this is polyatomic specie.=

= = = When we have an ion, we need to look what kind of charge the ion takes. = = if the ion have positive charge, then it is a Cation. = = If the ion have negative charge, then it is an anion. = = = = = = examples: = = OH -, this compound has 2 particles, one is O and one is H. Then we can say this is diatomic specie.And this one has negative charge, then this is also an anion. Also this one form by more than one atoms, this is also a polyatomic. = = = = Sr 2+, this compound has only one particle which is sr 2+, then we can say this is monatomic.and this ion has positive charge, we also can say this is a cation. = = = = = = = = = == = = =​= reference: text book