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Ionic Bonding. Writing Formulas Naming Compounds. Atoms and ions. Atoms are electrically neutral. Same number of protons and electrons. Ions are atoms, or groups of atoms, with a charge. Numbers of p+ and e- are different Only electrons can change They will be gained or lost. Anion.
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Ionic Bonding Writing Formulas Naming Compounds
Atoms and ions • Atoms are electrically neutral. • Same number of protons and electrons. • Ions are atoms, or groups of atoms, with a charge. • Numbers of p+ and e- are different • Only electrons can change • They will be gained or lost
Anion • Anegative ion. • Has gained electrons. • Non metals can gain electrons. • Charge is written as a superscript on the right. F1- Has gained one electron O2- Has gained two electrons
Cations • Positive ions. • Formed by losing electrons. • More protons than electrons. • Metals form cations. K1+ Has lost one electron Ca2+ Has lost two electrons
Ionic Compounds • Made of cations and anions. • Metals and nonmetals. • The electrons lost by the cation are gained by the anion. • The cation and anions surround each other. • Smallest piece is a FORMULA UNIT.
Chemical Formulas • Shows the kind and number of atoms in the smallest piece of a substance.
Formula Unit • The smallest whole number ratio of atoms in an ionic compound. • Ions surround each other so you can’t say which is connected to which.
Charges on ions • For most of s & p block elements, location on the Periodic Table can tell what kind of ion they form • Elements in the same group have similar properties. • Including the charge when they are ions.
The Charges of the Ions per Group 1+ 2+ 3+ 3- 2- 1-
F N Can also use electron dots Al K 3+ • If it has a few it loses them • If it has many, it gains enough for octet + 3- -
What about the others? • We have to figure those out some other way. • More on this later.
Systematic Naming • There are too many compounds to remember the names of them all. • Compound is made of two or more elements. • Put together atoms. • Name should tell us how many and what type of atoms.
Naming Monatomic Cations • Cation- if the charge is always the same (s & p block elements) just write the name of the metal. • Most transition metals can have more than one type of charge. • Indicate the charge with Roman numerals in parenthesis. • Co2+ Cobalt(II) ion
Name these • Na1+ Sodium ion • Ca2+ Calcium ion • Al3+ Aluminum ion • Fe3+ Iron(III) ion • Fe2+ Iron(II) ion • Pb2+ Lead(II) ion • Li1+ Lithium ion
Write Formulas for these K1+ • Potassium ion Mg2+ • Magnesium ion Cu2+ • Copper(II) ion Cr6+ • Chromium(VI) ion Ba2+ • Barium ion Hg2+ • Mercury(II) ion
Naming Monatomic Anions • Anions are always the same. • Change the element ending to – ide • F1- Fluorine
Naming Anions • Anions are always the same. • Change the element ending to – ide • F1- Fluorin
Naming Anions • Anions are always the same • Change the element ending to – ide • F1- Fluori
Naming Anions • Anions are always the same • Change the element ending to – ide • F1- Fluor
Naming Anions • Anions are always the same • Change the element ending to – ide • F1- Fluori
Naming Anions • Anions are always the same • Change the element ending to – ide • F1- Fluorid
Naming Anions • Anions are always the same • Change the element ending to – ide • F1- Fluoride
Naming Anions • Anions are always the same • Change the element ending to – ide • F1- Fluoride ion
Name these • Cl1- Chloride ion • N3- Nitride ion • Br1- Bromide ion Oxide ion • O2- Gallium ion • Ga3+
Write the formulas for these • Sulfide ion S2- • Iodide ion I1- • Phosphide ion P3- • Strontium ion Sr2+
Polyatomic ions • Groups of atoms that stay together and have a charge. • Covalently bonded • You have a paper with them on it – MEMORIZE THEM!
1- ions • Nitrate NO3- • Hydroxide OH-
Carbonate CO32- Sulfate SO42- 2- ions
Phosphate PO43- 3- ions 1+ ion • AmmoniumNH4+
Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • The name is just the names of the ions. • Cation first, Anion second • Easy with s & p block elements. • NaCl = Na+ Cl- = sodium chloride • MgBr2 = Mg2+ Br- = magnesium bromide • Na2S =
Naming Binary Ionic Compounds • Binary Compounds - 2 elements. • Ionic - a cation and an anion. • The name is just the names of the ions. • Cation first, Anion second • Easy with s & p block elements. • NaCl = Na+ Cl- = sodium chloride • MgBr2 = Mg2+ Br- = magnesium bromide • Na2S = Na+ S2- = sodium sulfide
Naming Binary Ionic Compounds • The difficulty in naming comes from the transition metals. • Cation name includes the charge. • The compound must be neutral. • same number of + and – charges. • Use the negative charge to find the charge on the positive ion.
Naming Binary Ionic Compounds • Write the name of CuO • Need to figure out the charge of Cu • O is 2- • copper must be 2+ • Copper(II) oxide • Example: Name CoCl3 • Cl is 1- and there are three of them = 3- • Co must be 3+ • Cobalt(III) chloride
Naming Binary Ionic Compounds • Example: Write the name of Cu2S. • Since S is 2-, the Cu2 must be 2+, so each one is 1+. • copper(I) sulfide • Example: Fe2O3 • Each O is 2- 3 x 2- = 6- • 2 Fe must = 6+, so each is 3+. • iron(III) oxide
Naming Binary Ionic Compounds Write the names of the following: • KCl • Na3N • CrN • Sc3P2 • PbO • PbO2 • Na2Se potassium chloride sodium nitride chromium(III) nitride scandium(II) phosphide lead(II) oxide lead(IV) oxide sodium selenide
Ternary Ionic Compounds • Will have polyatomic ions • At least three elements (3 capital letters) • Still just name the ions • NaNO3 • CaSO4 • CuCO3 sodium nitrate calcium sulfate copper(II) carbonate
Ternary Ionic Compounds ammonium oxide • (NH4)2O • Fe(OH)3 • LiCN • (NH4)2CO3 • NiPO4 iron(III) hydroxide lithium cyanide ammonium carbonate nickel(III) phosphate
Writing Formulas • The charges have to add up to zero. • Get charges on each ion. • Cation charge from name or periodic table. • Anion charge from periodic table or polyatomic. • Balance the charges by using subscripts. • Put polyatomics in parenthesis if there is more than one of them
Writing Formulas Example • Write the formula for calcium chloride. • Calcium is Ca2+ • Chloride is Cl1- • Ca2+Cl1- would have a 1+ charge. • Need another Cl1- • Ca2+Cl21- CaCl2
Crisscross Method • Switch the numerical value of the charges • Make them the subscripts Ba2+ N3- 3 2 Ba3 N2 • Reduce ratio if possible
Write the formulas for these • Lithium sulfide • tin (II) oxide • tin (IV) oxide • Copper (II) sulfate • Iron (III) phosphide • gallium nitrate • Iron (III) sulfide • ammonium sulfide Li2S SnO SnO2 CuSO4 FeP Ga(NO3)3 Fe2S3 (NH4)2S
Write the formulas for these • Ammonium chloride • barium nitrate NH4Cl Ba(NO3)2
Things to look for • If cations have (), the number is their charge. Not how many. • If anions end in -ide they are probably from the periodic table (Monoatomic) • Exceptions: Hydroxide (OH-) & Cyanide (CN-) • If anion ends in -ate or -ite it is polyatomic • The positive piece always gets written first • Hydrogen- it depends on where it’s at • If it is second, it’s named lik a nonmetal -hydride
Molecular Compounds Writing names and Formulas
Molecular compounds • Made of just nonmetal elements • Smallest piece is called a molecule • Are not held together because of opposite charges. • Can’t use charges to figure out how many of each atom
Easier to Name & Write Formulas than Ionic Compounds • For molecular compounds the name tells you the number & identity of the atoms. • The name uses prefixes to tell you the number of atoms in the molecule.
Prefixes • 6 hexa- • 7 hepta- • 8 octa- • 9 nona- • 10 deca- • 1 mono- • 2 di- • 3 tri- • 4 tetra- • 5 penta-
Naming • To write the name write two words • Exception - we don’t write mono- if there is only one of the first element. • No ao oo double vowels when writing name, BUT: io, oi, and ai are okay. • Example: SeCl2 selenium dichloride Prefix name Prefix name -ide
Writing Formulas • Use the prefixes to determine the number of the element • Use the name to determine what element • The element that ends in –ide will always come second. • Example: phoshporus trihydride PH3