Chapter 11 Chemical Bonds

Chapter 11 Chemical Bonds

Objectives

• 11.1 Describe how a compound differs from the elements that compose it

• 11.1 Explain what a chemical formula represents

• 11.1 State a reason why chemical bonding occurs

Objectives

• 11.2 Describe ionic and covalent bonds • 11.2 Identify the particles produced by ionic

bonding and by covalent bonding • 11.2 Distinguish between a polar and

nonpolar covalent bond

Objectives

• 11.3 Describe the dangers posed by hazardous compounds in the home

• 11.3 Demonstrate a knowledge of a safer alternative of compounds to use

• 11.4 Explain how to determine oxidation numbers

Objectives

• 11.4 Write formulas for compounds from their names

• 11.4 Name compounds from their formulas • 11.4 Describe hydrates and their formulas

Introductory

• Elements will have very different properties than the compounds they are in– Examples: Oxygen = Flammable, Gas at Room

Temperature– Hydrogen = Flammable, Gas at Room Temperature– Water (A compound of above) = Puts out fire,

liquid at room temperature– Many others, consider table salt

Why do Elements come together?

• To complete their outer shell– Have a noble gas configuration

• Elements which have a full outer shell tend to be chemically stable (unreactive)

• A full outer shell consists of 8 valence electrons– In the case of metals, losing all of their valence

electrons

BONDING

23

Bonds Between Atoms

Covalent

Ionic

Polyatomic Ions

Metallic

Molecular Substance Polar

NonpolarCoordinate Covalent

Network Solids

What are we going to learn about???

Important Words (Ie On Quiz)

• Anion- negative ion• Cation-positive ion• Octet Rule- rule that states that atoms tend to gain, lose,

or share electrons so that each atom has full outermost energy level which is typically 8 electrons.

• Polyatomic Ion- charged group of covalently bound atoms

• Polar-means ‘uneven’ sharing• Molecule-neutral group of atoms united by covalent

bonds• Hydrate-molecule surrounded by water• Oxidation number-number of electrons lost or gained• Covalent Bond- formed between 2 nonmetals

Ionic Bonds•What is an Ionic Bond?

- An Ionic Bond is a chemical bond resulting from the TRANSFER of electrons from one bonding atom to another

- It is composed of positive and negative atoms or particles

• When is an ionic bond formed?- An ionic bond is formed when a Metal and Non-Metal come together

What are some characteristics of an ionic bond?

1. Crystalline at room temperatures

2. Have higher melting points and boiling points compared to covalent compounds

3. Composed of Positive and Negative Charges, but do NOT conduct electricity

1. Corrosion stops batteries

Covalent Bonds•What is an Covalent Bond?

- A covalent bond is a chemical bond resulting from SHARING of electrons between 2 bonding atoms.

• What forms a covalent bond?- A covalent bond is formed between two nonmetals.

What are some characteristics of a covalent bond?

1. Covalent bonds have definite and predicable shapes.

2. Low melting and boiling points

3. Is a molecule

Molecules

• Composed of COVALENT Bonds– Electrons are shared

• Not all elements share equally though– Polar Molecules: Uneven sharing• Have a Positive and Negative side• If you have different elements, will have a Polar Bond• IE If Carbon and Oxygen make a bond, it will be polar

– Non-Polar Molecules: Even Sharing• Same element, IE Oxygen

Chemical Formulas

• Chemical Formulas tell us how many of each element are in a compound– A ratio for salts (ionic compounds) and an actual

number for molecules.• NaOH = 1 Na, 1 O, 1 H• H2O = 2 H, 1 O

• Mg(NO3)2 = 1 Mg, 2 N, 6 O

• 2 CO2 = 2 C, 4 O

+1+2 Ionic Charges -1-2-3

Formulas of Ionic Compounds

Formulas of ionic compounds are determined from the charges on the ions

atoms ions

–

Na + F : Na+ : F : NaF

sodium + fluorine sodium fluoride formula

Charge balance: 1+ 1- = 0

Writing a Formula

Write the formula for the ionic compound that will form between Ba2+ and Cl.Solution:1. Balance charge with + and – ions 2. Write the positive ion of metal first, and the

negative ion Ba2+ Cl Cl

3. Write the number of ions needed as

subscripts BaCl2

Ionic Nomenclature

• What is the formula of the following?• Potassium Oxide• K2O• Strontium Chloride• SrCl2

• Magnesium Nitride• Mg3N2

Ionic Nomenclature

• Potassium Phosphide• K3P• Magnesium Sulfide• MgS• Radium Flouride• RaF2

Ionic Nomenclature

• Binary Compounds of Metals with Fixed Charges: Given Formula, Write the Name

• The order for names in a binary compound is first the cation (Metal), then the anion (Non-Metal).

• Use the name of cation with a fixed oxidation state directly from the periodic table.

• The name of the anion will be made from the root of the element's name plus the suffix "-ide."

Practice Naming

• What is the name of the following?• MgO• Magnesium Oxide• NaF• Sodium Flouride• CaS• Calcium Sulfide

Transition Metals

Elements that can have more than one possible charge

MUST have a Roman Numeral to indicate the charge

on the individual ion.

1+ or 2+ 2+ or 3+Cu+, Cu2+ Fe2+, Fe3+

copper(I) ion iron(II) ion copper (II) ion iron(III) ion

Variable Charges

• Formula to Name• 1) Find the charge of the cation by – Finding total charge of anion and dividing by

number of cations• Example: FeCl3– We have 3 Chlorines, each has a -1 charge– The Fe needs to be +3 to balance it out

• 2) Say the cation with its Roman Numeral– Iron (III) Chloride

Variable Charges

• What is the name?• AuF3

• Gold (III) Flouride• AgF• Silver (I) Flouride• PbO2

• Lead (IV) Oxide

Variable Charges

• SnF2

• Tin (II) Flouride• MnO2

• Manganese (IV) Oxide• CrN• Chromium (III) Nitride• Sn3N4

• Tin (IV) Nitride

Variable Charges

• Name to Formula• The Roman Numeral tells you the charge• Balance the formula• Iron (III) Oxide– Fe has a +3 charge as denoted by the III– Oxygen always has a -2 charge– Cross them (Balance)– Fe2O3