Compounds & Bonding Chapters 6 & 7. V a l e n c e E l e c t r o n s E l e c t r o n s i n t h e o u t e r e n e r g y l e v e l a r e c a l l e d v a.

Compounds & Bonding

Chapters 6 & 7

V a l e n c e E l e c t r o n s

• E l e c t r o n s i n t h e o u t e r e n e r g y

l e v e l a r e c a l l e d v a l e n c e e l e c t r o n s

• I t i s t h e s e e l e c t r o n s t h a t d e t e r m i n e t h e f o r m a t i o n o f

c h e m i c a l b o n d s

V a l e n c e E l e c t r o n s

• C e r t a i n n u m b e r s o f v a l a n c e e l e c t r o n s a r e m o r e s t a b l e t h a n o t h e r s .

• A t o m s w i l l g a i n o r l o s e e l e c t r o n s t o b e c o m e m o r e s t a b l e .

Bonds Between Atoms

Covalent

Ionic

Polyatomic Ions

Metallic

Molecular Substance Polar

NonpolarCoordinate Covalent

Network Solids

What are we going to learn about???

Marriage

Divorce

Forming of a bond is like marriage

• More stable• exothermic

The breaking of a bond relates to a divorce.

• Less stable• Endothermic

C h e m i c a l B o n d T y p e s

• I o n i c• C o v a l e n t • M e t a l l i c

Examples

Types of Bonds

• There are two types of bonds – ionic & covalent

• Ionic bonds – a bond formed from a force between two opposite charges (+ and -).

• Covalent bonds – a bond formed from sharing electrons between two atoms.– Single bonds = one bond between only two

atoms– Multiple bonds = more than one bond

between atoms

What are some characteristics of an ionic bond?

1. Crystalline (salt crystals) at room temperatures

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

3. Conduct electrical current in molten or solution state but not in the solid state

4. Polar bonds

What are some characteristics of a covalent bond?

1. Covalent bonds have definite and predictable shapes.

2. Very strong

3. Low melting and boiling points

Types of Bonds

• Ionic bonds are made from metal and a nonmetal.

• Covalent bonds are made from two nonmetals.– Polar molecules have a (+) and a (–) end to

them (like ionic but weaker).– Nonpolar molecules have their electrons

shared evenly so that there are no ends like a magnet.

There are five different categories associated with covalent bonds. What are the 5 different categories?

Covalent

Molecular Substance Polar

NonpolarCoordinate Covalent

Network Solids

c

First, we are going to look at Polar Covalent…

What is polar covalent?

-Polar covalent is a description of a bond that has an uneven distribution of charge due to an unequal sharing of bonding electrons.

The boy is not equally sharing with anyone else but rather taking all the food for himself.

Next, we are going to look at Non-Polar Covalent…

What is non-polar covalent?

-Non polar covalent is a covalent bond that has an even distribution of charge due to an equal sharing of bonding electrons.

This couple is non- polar because they are sharing the drink equally between them.

Next, we are going to look at Molecular Substances…

What is a molecular substance?

-A molecular substance is a substance that has atoms held together by covalent bonds.

Name 2 Characteristics of a Molecular Substance.

1. Weak

2. Low melting and boiling points

Next, we are going to look at Coordinate Covalent…

What is a Coordinate Covalent Bond?

-A coordinate covalent bond is a bond formed when one atom donates both electrons that are shared.

People donate their blood to help others just like atoms “donate” electrons to form stable octets.

Polyatomic Bonds

What is a Polyatomic Bond?

- A polyatomic bond is charged group of covalently bonded atoms. It is made up of more than one atom.

Polyatomic ions usually have a charge because the collection of atoms has either gained an extra electron or else it has lost an electron.

Now, we are going to look at Network Solids…

What is a Network Solid?

-A network solid is a solid that has covalently bonded atoms linked in one big network or one big macromolecule.

Name 3 Characteristics of a Network Solid.

1. Poor conductors of heat and electricity

2. Hard / Strong

3. High melting and boiling points

Diphenylglycoluril assembles into a unique, two-dimensional hydrogen bonding network in the solid state, while exhibiting a twisted molecular structure.

Just as a summary to what each bond looks like…

P r e d i c t i n g B o n d T y p e s

• W i l l t h e s e p a i r s f o r m i o n i c o r c o v a l e n t b o n d s ?

– s o d i u m & c h l o r i n e– c a l c i u m & o x y g e n– c a r b o n & o x y g e n– a l u m i n u m & s u l f u r

Writing Chemical Formulas

• Binary Ionic Compounds – “bi” means two, compounds made of two elements– Example: potassium + iodine potassium

iodide K+ + I- KI

Oxidation number means charges on the “ions” (which means charges).

Let’s practice!!beryllium + selenium beryllium

selenide

Writing Chemical Formulas

• Polyatomic Ions – “poly” means many, compounds made with two or more elements

• Ex: ammonium + chlorine ammonium chloride NH4

+ + Cl- NH4Cl• (DO NOT BREAK APART POLYATOMIC ELEMENTS –

THEY TRAVEL TOGETHER!!)• Let’s practice!!

– carbonate + magnesium magnesium carbonate

Metallic BondingWhat is a Metallic Bond?

- A metallic bond occurs in metals. A metal consists of positive ions surrounded by a “sea” of mobile electrons.

Name 4 Characteristics of a Metallic Bond.

1. Good conductors of heat and electricity

2. Great strength

3. Malleable and Ductile

4. LusterThis shows what a metallic bond might look like.

Naming Ionic Compounds

• Use the whole first name (+ element) and the root of the second name (- element). Change the ending of the second element to -ide.

• If there is a polyatomic, the name DOES NOT change!!!

• Let’s practice!!CaCl2 AlNBPO4

Covalent Nomenclature Rules

• Prefix System (binary compounds)

1. Less e-neg atom comes first.

2. Add prefixes to indicate # of atoms. Omit mono- prefix on first element.

3. Change the ending of the second element to -ide.

Naming Covalent Molecules

• Use prefixes to tell how many atoms of each element in the compound

• Ex: CO2, N2O4, CCl4• Write the formula of

the following from the name: sulfur dichloride, phosphorus hexachloride, dihydrogen monoxide

# of atoms Prefixes

1 mono

2 di

3 tri

4 tetra

5 penta

6 hexa

7 hepta

8 octa

9 nona

10 deca

NCl4

N2O

SF6

nitrogen tetrachloride

dinitrogen monoxide

sulfur hexafluoride

Naming Covalent Molecules

arsenic trichloride

dinitrogen pentoxide

tetraphosphorus decoxide

AsCl3

N2O5

P4O10

Writing Molecular Structures

N O F

Cl

Br

I

H

Covalent Exceptions

• The Seven Diatomic Elements

Br2 I2 N2 Cl2 H2 O2 F2

Bond Polarity• Most bonds are a

blend of ionic and covalent characteristics.

• Difference in electronegativity determines bond type.

Bond Polarity

Examples:

• Cl2

• HCl

• NaCl

3.0-3.0=0.0Nonpolar

3.0-2.1=0.9Polar

3.0-0.9=2.1Ionic

REMEMBER…..• Electronegativity Trend (p. 161)

– Increases up and to the right. – There are values to each participating element

Chemical Changes

• Chemical reaction – a change in which one or more substances are converted into new substances

reactants products

• Conservation of mass – starting mass of the reactants must equal the final mass of the products -Ex: HgO Hg + O

10.0g = 9.3g + ?g

Review symbols

Chemical equation

Balancing Chemical Equations

• Conservation of mass states that the reactants and the products must equal.

• Balancing charges on ions sometimes makes the products equal the reactants.

• Coefficients (big numbers) are used to multiply the compounds and balance the mass on each side of the chemical equation.

Balancing Chemical Equations

1. __ Al + __O2 __Al2O3

2. __ H2 + __ O2 __H2O

3. __ S + __ O2 __SO3

Classifying Chemical Reactions

• Synthesis A + B AB• Decomposition AB A + B• Single displacement A + BC AC +

B• Double displacement AB + CD

AD + BC

Organic Compounds

• Organic compounds are made of mostly carbon and hydrogen atoms.

• Naming these compounds starts with the # of carbon atoms present using a particular prefix.

• Then the ending depends on the type of bonds made.

# of carbon atoms

Prefix for nam

e

1 meth-

2 eth-

3 prop-

4 but-

5 pent-

Type of

Bond

Suffix

single -ane

double

-ene

triple -yne