Chapter 7Ionic 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 ElectronsHydrogen and Helium are exceptions, they only need 2 to be full

Atoms will give, take, or share electrons to get to 8 Valence Electrons

ElectronegativityAbility of an atom to gain an electron.

ElectronegativityWhen 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 BondsForm 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

IonsWhen 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 FormationTo 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

PracticeFor 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”

PracticeFor each element, name the ion that it forms

Chlorine:

Beryllium:

Argon:

Ionic and Covalent BondsDay 2

  Element Symbol Name Formula

1Sodium Na Sodium Ion Na+

2Bromine Br Bromide Br-

3Magnesium Mg Magnesium Ion Mg2+

4Chlorine Cl Chloride Cl-

5Oxygen O Oxide O2-

6Boron B Boron Ion B3+

7Lithium Li Lithium ion Li+

8Neon Ne Neon Ne

9Phosphorus P Phosphide P3-

10Aluminum Al Aluminum ion Al3+

11Calcium Ca Calcium Ion Ca2+

12Iodine I Iodide I-

13Nitrogen N Nitride N3-

14Cesium Cs Cesium ion Cs+

15Sulfur S Sulfide S2-

16Fluorine F Fluoride F-

17Potassium K Potassium Ion K+

18Barium Ba Barium ion Ba2+

19Hydrogen H Hydride AND Hydrogen ion H+ AND H-

20Helium He Helium He

Ions ShortcutPull 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

With the criss-cross method you use the charge of the cation to figure out the subscript of the anion and vice versa

We write chemical formulas of ionic compounds using the criss-cross method

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 firstThe 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”

PracticeMg 2+ and Br - form what compound?

Al 3+ and O2- form what compound?

Ionic Bonding Day 2.5

TodayMini-quiz: How to find IonsReview how to write formulas for Ionic CompoundsDiscuss how to name Ionic CompoundsWHY Ionic Bonds form the compounds they doHW: 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 CompoundsUse the “Criss-Cross” Method to write ionic compounds: If the charges have the same number, you do NOT write the subscriptIf 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 CompoundsWhen 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”

Practice11. 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 3Polyatomic Ions

Polyatomic IonsA 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 methodSince 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 ionsLook 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 NamingK and SO4

Al and NO3

NH4 and Cl

Ionic Bonding Day 4Transition Metals

Transition MetalsEven 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 MetalsTwo 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