Atoms and Ions l Chemical Bond —force that holds 2 atoms together l Atoms are neutral=same number of protons as electrons l Ion—atom that has lost or gained electrons (it has a charge of + or -)
Remember l Only electrons can move l Atoms gain or lose electrons to achieve a noble gas configuration l To be stable
Keeping Track of Electrons l The electrons responsible for the chemical properties of atoms are those in the outer energy level. l Valence electrons - The s and p electrons in the outer energy level. l Core electrons -those in the energy levels below.
Keeping Track of Electrons l Atoms in the same column have the same outer electron configuration. l Have the same valence electrons. l Easily found by looking up the group number on the periodic table. l Group 2A - Be, Mg, Ca, etc.- l 2 valence electrons
Electron Dot diagrams l A way of keeping track of valence electrons. l How to write them l Write the symbol. l Put one dot for each valence electron l Don’t pair up until they have to X
The Electron Dot diagram for Nitrogen l Nitrogen has 5 valence electrons. l First we write the symbol. N l Then add 1 electron at a time to each side. l Until they are forced to pair up.
Write the electron dot diagram for l Na l Mg lClC lOlO lFlF l Ne l He
Electron Configurations for Cations l Metals lose electrons to attain noble gas configuration. l They make positive ions. l If we look at electron configuration it makes sense. l Na 1s 2 2s 2 2p 6 3s 1 - 1 valence electron l Na + 1s 2 2s 2 2p 6 -noble gas configuration
Electron Dots For Cations l Metals will have few valence electrons Ca
Electron Dots For Cations l Metals will have few valence electrons l These will come off Ca
Electron Dots For Cations l Metals will have few valence electrons l These will come off l Forming positive ions Ca +2
Electron Configurations for Anions * l Nonmetals gain electrons to attain noble gas configuration. l They make negative ions. l If we look at electron configuration it makes sense. l S 1s 2 2s 2 2p 6 3s 2 3p 4 - 6 valence electrons l S -2 1s 2 2s 2 2p 6 3s 2 3p 6 -noble gas configuration.
Electron Dots For Anions l Nonmetals will have many valence electrons. l They will gain electrons to fill outer shell. P P -3
Stable Electron Configurations l All atoms react to achieve noble gas configuration. l Noble gases have 2 s and 6 p electrons. l 8 valence electrons. l Also called the octet rule. Ar
Compounds l 2 atoms bonded together l Follow the Law of Definite Proportion— have a constant composition—the same # of atoms every time
3 Types of compounds l Ionic Bonds l Covalent or Molecular Bonds l Metallic Bonds
Ionic Bonds l Made by transferring electrons l Made of cations (metals) and anions (nonmetals) l The e- lost by the cation is gained by the anion l The cations and anions surround each other l Smallest piece is a Formula Unit
l Anions and cations are held together by opposite charges. l Packed into a regular repeating pattern that balances the forces of attraction and repulsion between the ions forming a crystal l Very strong bond l Ionic compounds are called salts.
Properties of Ionic Compounds l Crystalline structure. l A regular repeating arrangement of ions in the solid. l Ions are strongly bonded. l Structure is rigid. l High melting points- because of strong forces between ions.
Do they Conduct? l Conducting electricity is allowing charges to move. l In a solid, the ions are locked in place. l Ionic solids are insulators. l When melted, the ions can move around. l Melted ionic compounds conduct. l First get them to 800ºC. l Dissolved in water they conduct.
Writing the formula for compounds and Naming compounds Learning to speak the language
Chemical Formula l Shows the kind and number of atoms in the smallest piece of the substance l Nicotine l C 10 H 14 N 2
For Ionic Compounds: Systematic Naming l There are too many compounds to remember the names of them all l Compound-2 or more elements chemically combined l Pure substance l Name tell how many and what kind of atoms
Remember –Ionic Bonds l Anions and cations held together by opposite charges l Called salts l Simplest ratio is called formula unit l Bond is formed by transfer of electrons l Electrons are transferred to achieve a noble gas configuration
Ionic bonding or Formula Unit l Shows lowest whole # ratio of atoms in the crystal lattice l NaCl l MgCl 2
Charges on Ions l You can tell charge of an atom by its location l Elements in the same group have similar properties including the charge when they are ions l Oxidation number -the charge of the ion
Naming ions l We will use the systematic way. l Cation- if the charge is always the same (Group A) just write the name of the metal. l Transition metals can have more than one type of charge. l Indicate the charge with roman numerals in parenthesis.
Name these l Na +1 l Ca +2 l Al +3 l Fe +3 l Fe +2 l Pb +2 l Li +1
Write Formulas for these l Potassium ion l Magnesium ion l Copper (II) ion l Chromium (VI) ion l Barium ion l Mercury (II) ion
Naming Anions l Anions are always the same. l Change the element ending to – ide l F -1 Fluorine
Naming Anions l Anions are always the same. l Change the element ending to – ide l F -1 Fluorine Fluor + ide = Fluor ide
Name these l Cl -1 l N -3 l Br -1 l O -2 l Ga +3
Write these l Sulfide ion l iodide ion l phosphide ion l Strontium ion
Polyatomic ions l Group of atoms covalently bonded together that gain or lose an electron l LEARN YOU POLYATOMIC IONS! l Oxyanion –polyatomic ions composed of an element bonded to one or more oxygen atoms –Ate ions –Ite ions –Per –hypo
Polyatomic ions l Sulfate SO 4 -2 l Sulfite SO 3 -2 l Carbonate CO 3 -2 l Chromate CrO 4 -2 l Dichromate Cr 2 O 7 -2 l Phosphate PO 4 -3 l Phosphite PO 3 -3 l Ammonium NH 4 +1
Monatomic vs Polyatomic anions l S -2 monatomic l Sulfide ion l N -3 monatomic l Nitride ion l Bromide l Selenide l SO 4 -2 polyatomic l Sulfate ion l NO 3 - polyatomic l Nitrate l PO 4 -3 l Phosphate ion
Naming Binary Ionic Compounds l Binary Compounds - 2 elements. l Ionic - a cation and an anion. l To write the names just name the two ions. l Easy with Representative elements. l Group A l NaCl = Na + Cl - = sodium chloride l MgBr 2 = Mg +2 Br - = magnesium bromide
Naming Binary Ionic Compounds l The problem comes with the transition metals. l Need to figure out their charges. l The compound must be neutral. l same number of + and – charges. l Use the anion to determine the charge on the positive ion.
Naming Binary Ionic Compounds l Write the name of CuO l Need the charge of Cu l O is -2 l copper must be +2 l Copper (II) chloride l Name CoCl 3 l Cl is -1 and there are three of them = -3 l Co must be +3 Cobalt (III) chloride
Naming Binary Ionic Compounds l Write the name of Cu 2 S. l Since S is -2, the Cu 2 must be +2, so each one is +1. l copper (I) sulfide l Fe 2 O 3 l Each O is -2 3 x -2 = -6 l 3 Fe must = +6, so each is +2. l iron (III) oxide
Naming Binary Ionic Compounds l Write the names of the following l KCl l Na 3 N l CrN l Sc 3 P 2 l PbO l PbO 2 l Na 2 Se
Ternary Ionic Compounds l Will have polyatomic ions l At least three elements l name the ions l NaNO 3 l CaSO 4 l CuSO 3 l (NH 4 ) 2 O
Ternary Ionic Compounds l LiCN l Fe(OH) 3 l (NH 4 ) 2 CO 3 l NiPO 4
Writing Formulas l The charges have to add up to zero. l Get charges on pieces. l Cations from name on table. l Anions from table (ide) or polyatomic. l Balance the charges by using subscripts.
Writing Formulas l Write the formula for calcium chloride. l Calcium is Ca +2 l Chloride is Cl -1 l Ca +2 Cl -1 would have a +1 charge. l Need another Cl -1 l Ca +2 Cl 2 -1 1 (+2) and 2 (-1)=0 l CaCl 2
Write the formulas for these l Lithium sulfide l tin (II) oxide l tin (IV) oxide l Magnesium fluoride l Iron (III) phosphide l Iron (III) sulfide
Writing Ternary Ionic l Write the formula for calcium chlorate. l Calcium is Ca +2 Chlorate is ClO 3 -1 l Ca +2 ClO 3 -1 l Need another ClO 3 -1 l When you need to have more than one polyatomic ion you must use PARENTHESES l Ca(ClO 3 ) 2
Write the Formula l Lithium sulfate l tin (II) hydroxide l tin (IV) cyanide l Magnesium dichromate l Iron (III) Phosphate l Iron (III) sulfide