Presentation on theme: "Drill12/1/14 Rank the following elements by increasing atomic radius: Al, C, K, O Rank the following elements by increasing electronegativity: O, Ne,"— Presentation transcript:
Drill12/1/14 Rank the following elements by increasing atomic radius: Al, C, K, O Rank the following elements by increasing electronegativity: O, Ne, S, Al
Drill12/1/14 Rank the following elements by increasing atomic radius: O, C, Al, K Rank the following elements by increasing electronegativity: Ne, Al, S, O
Agenda Quest – Pd 4B and 4A Notes on Ionic and Covalent Cpds (all classes)
Announcement Lab next class. Must wear appropriate clothing and shoes.
Used to indicate the distribution of electrons among the bonded atoms in a molecule (covalent bond) or a polyatomic ion.
How are they used? Naming compounds Writing formulas Balancing chemical equations
Oxidation Numbers (review) Remember, most atoms strive to have eight valence electrons (some are satisfied with only two) Atoms will form various bonds by gaining, losing, or sharing electrons, in order to satisfy the Octet Rule
Oxidation Numbers An atom’s electron configuration is used to determine how many electrons need to be gained, lost, or shared Example – Na (11 electrons) 1s 2 2s 2 2p 6 3s 1 – 1 valence electron In order for Na to have eight valence electrons, would it be easier for it to gain 7 electrons, or lose 1? Losing 1 is easier
Oxidation Numbers When Na loses an electron it becomes an Na +1 ion 1s 2 2s 2 2p 6 3s 1 becomes… 1s 2 2s 2 2p 6 – 8 valence electrons Na carries a +1 charge because it has lost an electron, and it now has more positively charged protons than negatively charged electrons
Oxidation Numbers Another Example – Fluorine (9 electrons) 1s 2 2s 2 2p 5 – 7 valence electrons In order for F to have eight valence electrons, would it be easier for it to gain 1 electron, or lose 7? Gaining 1 is easier
Oxidation Numbers When F gains an electron it becomes an F -1 ion 1s 2 2s 2 2p 5 becomes… 1s 2 2s 2 2p 6 – 8 valence electrons F carries a -1 charge because it has gained an electron, and it now has more negatively charged electrons than positively charged protons
Oxidation Numbers There is a fairly consistent pattern to oxidation numbers with families Transition Metals and Inner Transition Metals usually have a varying number of valence electrons Some don’t – Zn +2, Cd +2, Sc +2, Ag +1
Complete with the people in your row. Oxidation Number Practice
List the oxidation number for the following families – Alkali metals – Alkaline earth metals – Halogens – Noble Gases Write the oxidation numbers for the following elements Aluminum Sulfur Cesium Iodine Xenon Strontium Tin Selenium
No Drill12/3/14 You are responsible for memorizing 15 polyatomic ions for the next test. They are on my webpage. Best way to memorize is to make flashcards.
Objectives SWBAT name binary ionic compounds. SWBAT write formulas for binary ionic compounds.
Bond Type by Electronegativity Electronegativity Difference Bond Type <0.3nonpolar covalent Between 0.3 & 1.7polar covalent >1.7ionic
Bond Polarity and Electronegativity Nonpolar covalent bond – a bond in which the bonding electrons are shared equally by the bonded atoms –Example: Cl-Cl Polar covalent bond – a bond in which the bonded atoms have an unequal attraction for the shared electrons –Example: H-Cl
Definition An ionic compound is composed of positive (cation) and negative ions (anion) that are combined so that the number of positive and negative charges are equal.
Think About It…. You already know how to name a binary ionic compound, but you may not know it yet. Think about table salt. What is its chemical name? What rule seems to be in effect when naming it? How can we apply this rule to the naming of all simple ionic compounds?
How might we name these compounds? NaBr KF BaCl 2 NaI MgO
Naming an Ionic Compound To name a simple binary ionic compound, simply change the ending of the second ion to –ide –For example, NaCl isn’t sodium chlorine, but sodium chloride instead
Writing the Formula for an Ionic Compound You already know how! However, there is an easier way to do it.
Criss-Cross Method 1. Do the sum of the charges for the two ions = 0? 2. If not, use the criss-cross method 3. The charge on one ion becomes the subscript on the other (Cross the charges of the ions).
Practice Problem Using the criss-cross method, determine the formula for aluminum oxide.
Answer You do not need to write the charges for the ions in the formula.
Practice Problem Using the criss-cross method, determine the formula for calcium sulfide.
Types of Ions Monatomic Ion – an ion consisting of “one-atom” –For example, K +1 Polyatomic Ion – an ion made from more than one atom –For example, NH 4 +1
Naming an Ionic Compound that Contains a Polyatomic Ion Ionic compounds containing polyatomic ions are named in a very similar way as those containing monatomic ions –Name the polyatomic ion exactly as it appears on the ion sheet –Example: Na 2 SO 4 is sodium sulfate
Writing the Formula for an Ionic Compound that Contains a Polyatomic Ion Use the criss-cross method to write the formula for ionic compounds containing polyatomic ions When the criss cross method forces you to add a subscript to a polyatomic ion which already has a subscript, then you must use parentheses to separate the subscripts
Example Problem Using the criss-cross method, write the formula for ammonium oxide.
Roman Numerals Some metals have varying charges (usually transition metals). When an element commonly has more than one charge, you must use Roman numerals to name it.
Example There are 2 common ions for iron: Fe +2 and Fe +3 Fe 2 O 3 would be named iron(III) oxide –The (III) corresponds to the charge on the metal iron FeO would be named iron(II) oxide –The (II) corresponds to the charge on the metal iron
Review A simple ionic compound is made up of a positive __________ ion and a negative ____________ ion.
Naming Ionic Compounds Ionic compounds are named just as they are read, except that the anion end is changed to –ide. For example, NaCl is not called sodium chlorine, but sodium chloride instead.
Examples Name the following compounds: –MgI 2 –RbBr –SrS –CaO –Li 3 P –NaF
Metals With More Than One Charge On your “Ion Sheet,” you can see that some metals can have more than one charge. –For example, copper can have a 1+ or 2+ charge If an ion can have more than one charge, you must specify its charge in the formula name using ROMAN NUMERALS
Example Name this compound: CuBr This compound would be named Copper(I) Bromide since copper is existing in the 1+ state CuBr 2 would be named Copper(II) Bromide since copper is in the 2+ state
More Practice Name the following ionic compounds: –FeO –Cu 3 N 2 –Fe 2 O 3 –Cu 3 P –CuCl –FeCl 2