Ionic and Covalent Bonds Chapter 7 Ionic and Covalent Bonds

Review Chemical Bonds form between 2 or more atoms to form molecules Two types of chemical bonds: Ionic Bonds & Covalent Bonds

Ionic Bonds & Covalent Bonds Ionic Bonds- Electrons are transferred between a metal and a non-metal Covalent Bonds- Electrons are shared between two non-metals Remember: The “stairs” on your periodic table separate the metals and non-metals

In this Chapter… You will understand HOW and WHY Ionic and Covalent Bonds form To start- remember that an element becomes stable with 8 Valence Electrons Hydrogen and Helium are exceptions, they only need 2 to be full Atoms will give, take, or share electrons to get to 8 Valence Electrons

Electronegativity Ability of an atom to gain an electron.

Electronegativity When two atoms have a big difference in electronegativity the electron gets transferred When there is a small difference the atoms share the electron This is WHY the atoms form the type of bonds that they do

Ionic Bonds Form between a metal and a non-metal There’s usually a big difference in electronegativity, which causes the metal to give its electrons to the non-metal Example: K and O (3.5 - .8 = 2.7 difference) They transfer enough electrons so that both the metal and non-metal have 8 Valence Electrons

Ions When atoms give or take electrons they become charged Ions Metals lose electrons to become cations (+) Non-metals gain electrons to become anions(-) Opposite charges attract, ions come together to form neutral molecules

Ion Formation To figure out what ion an element will form: If it is a metal: Find out the number of valence electrons it needs to LOSE to get to zero. Many Transition Metals can form more than 1 Ion If it is a non-metal: Find out the number of valence electrons it needs to GAIN to get to 8 Hydrogen can both lose and gain 1 electron

Practice For each element, find out the ion that it forms Chlorine: Beryllium: Argon:

Simple Ion Nomenclature (naming) Simple cations are named by saying the element and adding the word “ion.” Na+ is called “sodium ion” Mg2+ is called “magnesium ion” Simple anions are named by dropping the ending off the element name and adding “ide.” F- is called “fluoride” O2- is called “oxide” N3- is called “nitride”

Practice For each element, name the ion that it forms Chlorine: Beryllium: Argon:

Ionic and Covalent Bonds Day 2

Hydride AND Hydrogen ion H+ AND H- Helium He   Element Symbol Name Formula 1 Sodium Na Sodium Ion Na+ 2 Bromine Br Bromide Br- 3 Magnesium Mg Magnesium Ion Mg2+ 4 Chlorine Cl Chloride Cl- 5 Oxygen O Oxide O2- 6 Boron B Boron Ion B3+ 7 Lithium Li Lithium ion Li+ 8 Neon Ne 9 Phosphorus P Phosphide P3- 10 Aluminum Al Aluminum ion Al3+ 11 Calcium Ca Calcium Ion Ca2+ 12 Iodine I Iodide I- 13 Nitrogen N Nitride N3- 14 Cesium Cs Cesium ion Cs+ 15 Sulfur S Sulfide S2- 16 Fluorine F Fluoride F- 17 Potassium K Potassium Ion K+ 18 Barium Ba Barium ion Ba2+ 19 Hydrogen H Hydride AND Hydrogen ion H+ AND H- 20 Helium He

Ions Shortcut Pull out your periodic tables! Group 1 = 1+ Group 2 = 2+ Group 13 = 3+ Group 14 = 4+ or 4- ***Depends on what it bonds with Group 15 = 3- Group 16 = 2- Group 17 = 1-

Simple Ionic Compounds Ions come together to form neutral compounds Today we will learn how to: Write the chemical formula of the compound created Figure out the name for the compound

Chemical Formulas of Ionic Compounds We write chemical formulas of ionic compounds using the criss-cross method With the criss-cross method you use the charge of the cation to figure out the subscript of the anion and vice versa

Criss - Cross Method When possible, reduce the subscripts to get the most simple version of the chemical formula Situation 1: Ions with the same charge Mg2+ and O2- would be written as MgO, NOT Mg2O2 Situation 2: Any subscript with a 1 Mg2+ and Cl- would be written as MgCl2 NOT Mg1Cl2

Naming Ionic Compounds When naming ionic compounds, simply write the element name of the metal followed by the ion name of the nonmetal. The metal ion (cation) is always written first The name of the metal is capitalized while the ion of the non-metal is not NaCl is called “Sodium chloride” CaCl2 is called “Calcium chloride”

Practice Mg 2+ and Br - form what compound? Al 3+ and O2- form what compound?

Ionic Bonding Day 2.5

Today Mini-quiz: How to find Ions Review how to write formulas for Ionic Compounds Discuss how to name Ionic Compounds WHY Ionic Bonds form the compounds they do HW: Ionic Bonding WS

Mini-Quiz: Take out a half sheet of paper and your periodic table What Ions do the following elements form? S Li Al Ne Br

Naming Ionic Compounds Use the “Criss-Cross” Method to write ionic compounds: If the charges have the same number, you do NOT write the subscript If the number is a 1, you do NOT write the subscript

Practice- Take out your worksheet from yesterday 1. Na and Br: Na+ and Br- so NaBr 2. Ca and Cl Ca2+ and Cl- so CaCl2 3. Mg and S Mg2+ and S2- so MgS Try #4 Al and O and #5 Li and P

Naming Ionic Compounds When naming ionic compounds, write the element name of the metal followed by the ion name of the nonmetal. NaCl is called “Sodium chloride” CaCl2 is called “Calcium chloride”

Practice 11. K and O 12. Mg and I 13. Al and Cl Try #14 Ca and Br and #15 Na and N on your own!

Ionic Bonds Day 3 Polyatomic Ions

Polyatomic Ions A polyatomic ion is made up of 2 or more atoms that are covalently bonded, but have an overall charge Even though they are multiple atoms, we treat it like 1 ion A list of polyatomic ions with their charges is given on your reference sheet– you need to keep this safe!

Polyatomic Ions in Formulas Still use the same criss-cross method Since the subscript applies to the ENTIRE polyatomic ion, the ion goes in ( ) with the subscript on the outside Example: Mg and OH Mg2+ and OH- form Mg(OH)2

Practice writing formulas K and SO4 Al and NO3 NH4 and Cl

Naming polyatomic ions Look up the name of the polyatomic ion using the polyatomic reference sheet The regular ion uses the same naming as usual Full name for Cation (+) -ide ending for Anion (-) Examples: Mg and OH Magnesium Hydroxide Na and MnO4 Sodium Permanganate

Practice Naming K and SO4 Al and NO3 NH4 and Cl

Ionic Bonding Day 4 Transition Metals

Transition Metals Even though transition metals technically have 2 valence electrons, they don’t act like it Transition Metals can form a wide variety of cations We will use our reference sheet to see what ions the various transition metals can form

Figuring out transition metal charge If the ion that goes with the metal does NOT have a subscript, then the metal has the same charge as the other ion AuCl = Au+ because Cl- FeO = Fe2+ because O-2 If the ion that goes with the metal DOES have a subscript, then the metal has the ion charge of the subscript AuCl3 = Au3+ Fe2O3 = Fe3+

Practice What is the charge on Zn in ZnCl2? What is the charge on Cr in CrO? What is the charge on Co in CoBr3? What is the charge on Ni in NiSO4?

Figuring out ion charge without the formula Without the formula given, you cannot know which ion charge to use (when there is more than one choice) When the formula is not given, you must write the formula for all possible ion choices Example: What is the formula for Cu and Cl? CuCl and CuCl2 are both the correct answer, you need both!

Practice What are the possible formulas for… Fe and N? Ag and Br? Au and O?

Naming Transition Metals Two types of names- standard and common name Standard name: Regular metal name with the ion number in roman numerals in parenthesis Example: Fe2+ Iron (II) Common name: Based on Latin Names Example: Fe2+ Ferrous Both are found on your transition metals reference sheet!

Practice Name CuCl2 with both the standard and common names Name AuCl and AuCl3 with their standard names