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 Nonpolar Coordinate 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 H 2 O = 2 H, 1 O Mg(NO 3 ) 2 = 1 Mg, 2 N, 6 O 2 CO 2 = 2 C, 4 O

+1+2 Ionic Charges-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: = 0

Writing a Formula Write the formula for the ionic compound that will form between Ba 2+ and Cl . Solution: 1. Balance charge with + and – ions 2. Write the positive ion of metal first, and the negative ion Ba 2+ Cl  Cl  3. Write the number of ions needed as subscripts BaCl 2

Ionic Nomenclature What is the formula of the following? Potassium Oxide K 2 O Strontium Chloride SrCl 2 Magnesium Nitride Mg 3 N 2

Ionic Nomenclature Potassium Phosphide K 3 P Magnesium Sulfide MgS Radium Flouride RaF 2

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 or 3+ Cu +, Cu 2+ Fe 2+, Fe 3+ 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 –F–Finding total charge of anion and dividing by number of cations Example: FeCl 3 –W–We have 3 Chlorines, each has a -1 charge –T–The Fe needs to be +3 to balance it out 2) Say the cation with its Roman Numeral –I–Iron (III) Chloride

Variable Charges What is the name? AuF 3 Gold (III) Flouride AgF Silver (I) Flouride PbO 2 Lead (IV) Oxide

Variable Charges SnF 2 Tin (II) Flouride MnO 2 Manganese (IV) Oxide CrN Chromium (III) Nitride Sn 3 N 4 Tin (IV) Nitride

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