Bell Ringer 9/18/13 Copy and complete the following: Locate the Halogens and Noble Gases on the Periodic Table. To what Group are they each located?

Chemical Bonding Physical Science

Chemical Bonds When two or more atoms attach to each other, they form a chemical bond Compounds are any two elements chemically bonded Water Sugar Salt And almost all other substances!!!! Electrons are responsible for the type, strength, and size of a chemical bond

Lewis Structures Bohr-Rutherford diagrams are large and difficult to show relationships between multiple atoms Lewis diagrams are used to show multiple atoms Lewis diagrams show only the valence electrons

Lewis Structures Valence electrons form the charge of an atom Electrons are always trying to get together in groups of 8 (forget shells for a minute) Elements that have 8 valence electrons have FULL outer groups We call these elements NOBLE or INERT gases, they are found in group 8

Lewis Structures Label the Nobel (Inert) gases on your chart

Lewis Structures Elements with 1 valence electron are called the Alkali metals (group 1) (Label)

Lewis Structures Elements with 2 valence electrons are called the Alkaline Earth metals (group 2) (Label)

Lewis Structures Elements with 7 valence electrons are called the Halogens (group 7) (Label)

Sy Lewis Structures Consist of Element Symbol Electrons in each open spot Sy

Cl 7 Lewis Structures Lewis Structure Draw the element symbol Determine the # valence electrons Starting at the top, going clockwise, place one electron in each spot around the element symbol Lewis Structure Cl

Lewis Structure Draw the Lewis Structure for Aluminum! Al

Li Quick Recap! Draw the Lewis Structure for Lithium! Draw the Rutherford-Bohr Diagram for Lithium! - - Li 3P 3N -

A note about charges… Writing a charge Valence electrons, Bohr-Rutherford, and Lewis diagrams are used to determine charge Charges are a shortcut to determining bonding properties RULES OF CHARGE IF the # of valence electrons is GREATER than 4, the charge is negative (Mostly) IF the # of valence electrons is less than 4, the charge is positive (Mostly) Charges are in reference to a full shell of 8

A note about charges… For example, Aluminum has 3 valance electrons The possible charges are +3 OR -5 It either has 3 OVER a full shell, or 5 LESS than a full shell Because the number 3 is less than 4, we use the charge of +3

Charges Any element with a charge is called an ION, the charge is an ionic charge What are the ionic charges of the elements in the table? Sodium? +1 Nitrogen? -3 Oxygen? -2 Argon? Sodium? Nitrogen? Oxygen? Argon?

Charges

Charges A few exceptions! Example: Boron Metals are always a positive charge!! Non metals are always negative!! Metalloids can go either way (you are not responsible for choosing – I will tell you) Example: Boron According to rule of 4’s….its a +3 charge But since it’s a nonmetal, we use -5!

Rules of Bonding All compounds must have neutral charges (That means the positive charges (cations) and the negative charges (anions) must equal Subscript numbers are used to show the number of ions Coefficients are used to show the number of molecules

“1’s” are implied and not written Rules of Bonding 2H2O Subscript 1 atom of O “1’s” are implied and not written Coefficient Subscript 2 atoms of H

Rules of Bonding H2O O H H

Rules of Bonding H2O O H H

Rules of Bonding Try this one! NaCl (table salt) Na Cl

Rules of Bonding Last One! Aluminum Bromide Br Al

Chemical Bonding Several Types including Covalent Bonds* Ionic Bonds* Metallic (only between metals)

Covalent Bonds Electrons are shared between two or more atoms Covalent bonds can exist between atoms of the same type…for example N-N (N2) or O- O (O2) Covalent bonds can form single, double, or triple bonds Covalent bonds are strong and usually result in stable molecules Carbon always forms covalent bonds and forms the basic molecules for all life substances

Ionic Bonds Usually formed by members of the Alkali group (ones with +1 electron) Electrons are donated to another molecule Between elements from opposite sides of the chart Forms crystals (salts) & most dissolve in water

Forming Compounds Write ions with charges Cross charges Write subscripts (omit “1’s”) Use parenthesis if needed

O H H+1 O-2 H2 O1 H2O Forming Compounds What is the molecular formula of water? H+1 O-2 H2 O1 H O H2O

Reduce like a fraction to lowest denominator Forming Compounds What is the molecular formula of carbon dioxide? C+4 O-2 C2 O4 Yikes! Reduce like a fraction to lowest denominator ****note**** C2O4 CO2

Al+3 S-2 Al2 S3 Al2S3 Forming Compounds What is the molecular formula of a compound that has aluminum and sulphur? Al+3 S-2 Al2 S3 Any guesses on the name? Al2S3

Naming Binary Covalent

Ionic or Covalent??? Ionic - Starts with a metal Swaps valence electrons Covalent - 2 non metals Shares valence electrons

Naming Binary Covalent Compounds Before you can name binary covalent compounds, you MUST know the prefixes!

Prefixes Mono Di Tri Tetra Penta Hexa Hepta Octa Nona Deca 1 2 3 4 5 6 7 8 9 10

Rules for naming Binary Covalent Compounds Name the prefix for the number of atoms of the first element Then name the first element Name the prefix for the number of atoms of the second element Than name the root of the second element with the ending -ide

Note… No charges are used in Binary Covalent Compounds If the 1st prefix is mono….DROP IT! When the prefix ends in an o or a, and the name of the element begins with a vowel, the o or a is often dropped

Examples What is the name of N2O4? N2  di nitrogen O4  tetra oxide Since oxide begins with a vowel, we will drop the a in tetra Dinitrogen tetroxide

More examples Name SO2 S  mono sulfur But mono is with the 1st element, so it will be dropped  sulfur O2  dioxide Sulfur dioxide

More examples Write the formula for dichlorine monoxide Dichlorine  Cl2 Monoxide  O Cl2O

More examples Write the formula for disulfur dichloride Disulfur  S2 Dichloride  Cl2 S2Cl2

Ionic

Writing Chemical Formulas Before we can name compounds, we must know the rules for writing formulas The modern model of how atoms react to form compounds is based on the fact that the stability of a noble gas results from the arrangement of its valence electrons. This model of chemical stability is called the octet rule.

Charges or Oxidation Numbers Elements will gain or loose electrons to have 8 valence electrons. To review, how many valence electrons does Na have? 1 What will happen to that valence electron You will loose that electron If you loose that electron, what charge will you have? +1

Charges or Oxidation Numbers Group 1A  +1 Group 2A  +2 Group 3A  +3 Group 4A  +4 / - 4 Group 5A  -3 Group 6A  -2 Group 7A  -1 Group 8A  STABLE The charges of monatomic ions, or ions containing only one atom, can often be determined by referring to the periodic table

Ions An ion is an atom or group of combined atoms that has a charge because of the loss or gain of electrons. A compound that is composed of ions is called an ionic compound. Only the arrangement of electrons has changed. Nothing about the atom’s nucleus has changed. Ionic compounds are usually start with a metal or a polyatomic ion (like ammonium) In ionic compounds, you will SWAP valence electrons

Ions A cation, or positive ion, is formed when an atom loses one or more electrons. An anion, or negative ion, is formed when an atom gains one or more electrons. A monatomic ion is one element with a charge A polyatomic ion is more that one element with a charge

Formation of Ionic Compounds Remember that objects with opposite charges attract each other. The strong attractive force between ions of opposite charge is called an ionic bond. Don’t forget that even though the ions have charges, the overall charge of the compound will be … ZERO!

Examples of Formula Writing Write the formula for the compound formed between sodium and chloride Na  Na +1 Cl  Cl -1 Na+1 Cl-1 (criss-cross charges & reduce) Na1Cl1 (What’s wrong here?) Do Not write the 1’s NaCl

More examples Write the formula between Mg and Br Mg  +2 Br  -1 Mg+2 Br -1 (Bring down charges) MgBr2

More examples Write the formula for the compound formed between Ca and S Ca  Ca +2 S  S -2 Ca+2 S-2 (Bring down charges) Ca2S2 (What’s wrong?) Simplify! CaS

More examples Copper (II) and chlorine CuCl2 Silver and nitrogen Ag3N Magnesium and sulfur Calcium and selenium Potassium and oxygen Lithium and phosphate sodium and chlorine CuCl2 Ag3N MgS CaSe K2O Li3PO4 NaCl

Don’t Forget! You have to remember the elements that form multiple charges (the ones with the roman numerals) That roman numeral will tell you the charge! For example: Copper (II)  Cu +2

Multiple Charges to Remember Copper Iron Lead Tin Gold +1 and +2 +2 and +3 +2 and +4 +1 and +3

Naming ionic compounds In naming ionic compounds, name the cation first, then the anion. Monatomic cations use the element name. Monatomic anions use the root of the element name plus the suffix -ide. (This means 1 element with a negative charge will end in –ide).

Naming ionic compounds If an element can have more than one oxidation number, use a Roman numeral in parentheses after the element name, for example, iron(II) to indicate the Fe 2+ ion. For polyatomic ions, use the name of the ion.

Simply put.. All you have to do is name the 1st thing then name the 2nd thing

Examples NaCl MgS K3P CaCl2 CuBr AlCl3 CuS Fe3N2 Sodium chloride Magnesium sulfide Potassium phosphide Calcium chloride Copper (I) bromide Aluminum chloride Copper (II) sulfide Iron (II) nitride

More examples Lead (IV) Oxide Potassium fluoride Iron (II) chloride Calcium sulfide Lithium nitrode Sodium selenide Tin (II) chloride PbO2 KF FeCl2 CaS Li3N Na2Se SnCl2

Mixed examples (remember to figure out what type of compound it is 1st KCl CO2 Na2S LiBr CuI2 Fe2O3 Al2O3 Potassium chloride Carbon dioxide Sodium sulfide Lithium bromide Copper (II) iodide Iron (III) oxide Aluminum oxide

More Mixed Examples Carbon tetrachloride Phosphorous pentachloride Aluminum oxide Copper (II) nitrate Chlorous acid Hydrophosphoric acid Iron (III) hydroxide CCl4 PCl5 Al2O3 Cu(NO3)2 HClO2 H3P Fe(OH)3