DO NOW:1. Make a cover

page in your NB for Chapter 5.

2. Draw a Bohr diagram for sulfur.

3. How many valence electrons does sulfur have?

Chapter 5

Atoms and Bonding

Do Now: Draw a Bohr diagram for sulfur. How many valence electrons does S have?

Sulfur• 16 electrons• 6 valance electrons

16 P16 N

Elements 1 - 201st level = 22nd level = 83rd level = 84th level = 2

Elements 21 – 1121st level = 22nd level = 8

3rd level = 18*4th level = 32*5th level = 32*

*sub-levels exist

Electron Shell

Capacities:

All atoms want to achieve a full octet; which means they have a full outer valence shell

Neon • 10 electrons• 8 valence electrons

Ne

Why Do Valence Electrons Matter?• The valence electrons show WHY certain

elements bond with other elements to form compounds.

S

H H

Sulfur’s 6 valence

electrons WANT 2

more electrons

2 Hydrogen atoms will

make 8 total

Remember, the # of valance electrons matches its family #

Alk

ali M

etal

s

Alk

alin

e E

arth

Met

als

Transition Metals

Bor

on

Fam

ilyC

arbo

n F

amily

Nitr

ogen

Fam

ily

Oxy

gen

Fam

ily

Hal

ogen

sN

oble

G

ases

*Matches 2nd digit groups 13 -18

Electron Dot Diagrams AKA Lewis Structure

• Symbol of an element surrounded by “dots”. • Each dot represents one valence electron.

Electron Dot DiagramsAKA Lewis Structure

• The Element Symbol serves as the representation of the nucleus.

• Dots are added at 12 o’clock, 3 o’clock, 6 o’clock, and 9 o’clock.

Carbon has only 4 electrons in the 2nd energy level so we need only represent those 4

Electron Dot DiagramsAKA Lewis Structure

• Only valence electrons are shown.

• Maximum of 8 dots (electrons)

Electron Dot DiagramsAKA Lewis Structure

Oxygen Group = Valance electrons =

Lewis Structure Practice

Draw Electron Dot Diagrams for Beryllium and Sulfur

Chlorine Group = Valance electrons =

166

177

Beryllium = Group 2 = 2 valance electrons

Sulfur = Group 16 = 6 valance electrons

To Become Stable Atoms… They Bond

Chemical Bonds• Atoms with unfilled valence shells are considered

unstable.• Atoms will try to fill their outer shells by bonding

with other atoms.• The number of valence electrons will determine

how many bonds the atom can form.• A chemical bond is the force that holds the

molecules together

• Two types of bonds we will discuss:– Ionic bonds– Covalent bonds

Understanding chemical formulas:

BaF2

Subscripts: tells how many atoms of that element are in the compound

• refers only to the element preceding it • The subscript 2 in this formula is for the F (fluorine)• Ba (barium) only has one atom (1’s are not written)

Chemical Bonds are represented with Chemical Formulas

3BaF2

Coefficients: refers to each element that follows• Multiply the coefficient with all subscripts• The 3 in this example means there would be

3 Ba (barium) and 3 F2 (a total of 6 fluorine) atoms

Al(NO3)3

Parentheses: The subscript outside the parentheses refers to all the elements inside the parentheses

• Multiply the subscript outside with each subscript inside to get the total number of atoms

• In this example there are: one Al (aluminum), three N (nitrogen), and nine O (oxygen) atoms

Identifying and Counting Atoms in a Chemical Formula

Try It: Count the Atoms in each Chemical Formula

1

1 2

12

6

24

42

1

6

9

6

22

1

4

4

12

21

Try It: Count the Atoms in each Chemical Formula

Back to Bonding…

+1

+20

-3 -2 -1+3+4-4

Valence Electrons Determine Oxidation Numbers

Oxidation Numbers Shows the number of electrons an atom will

gain, lose, or share. Positive (+) or negative (-) number assigned

to an element. Comes from its family number on the Periodic

table1) Metals (Families 1, 2, 13 +1, +2, +3)2) Nonmetals (Families 15, 16, 17 -3, -2, -1)3) Noble Gases (Family 18 0)4) Transition metals have various oxidation numbers

between 1 and 4

+1

+2

0

-3 -2 -1+3+4-4

Atoms that are no longer neutral are called ions

Ions:• An atom or groups of atoms that have lost or

gained electrons• Atom becomes either negatively (-) or

positively (+) charged• Change occurs since the ratio of protons to

electrons is not equal

Ions form from atoms who gain or lose electrons

Cation: positive ion• When an atom loses an electron it becomes positively charged• Ex: Calcium ion = Ca+2

Anion: negative ion• When an atom gains an electron

it becomes negatively charged• Ex: Fluorine ion = F–

(the 1 is inferred)

Oxygen at the Playground

Polyatomic Ions• Ions that stay together

as a group

ammonium nitrate

Poly- ionic name: ammonium nitrate

+

Polyatomic Ions• Ions that stay together

as a group

ammonium nitrate

Poly- ionic name: ammonium nitrate

+

Time to Bond Ions• Each index card represents either a cation (+) or an anion (-)• Any opposite charged ions can bond• Writing the chemical formula and names:

1. Oxidation numbers will become subscript numbers for the opposite element

2. Write both element names, but change the second element ending to “ide”

Oxygen at the Playground

Ionic BondingHow does it work?

• Ionic bonding takes place between metals and non-metals.

• In an ionic bonds :• oppositely charged ions (+) and (-) attract• electrons are transferred• Ex. NaCl (Na +1 Cl -1)

Naming Ionic Compounds• Name of the + ion comes first, and - ion comes second

• Metal + Nonmetal • Monatomic ions: change nonmetal ending to –ide

• Ex: Mg +2 + F -1 becomesMgF2 or Magnesium Fluoride

• Polyatomic ions: change nonmetal ending to –ate or –ite

Ex: NaNO3 = sodium nitrate Mg3(PO4)2 = magnesium phosphate

Do Now1. Draw the Lewis structure for: • Magnesium +2• Iodine -1

2. Write the chemical formula these two ions would create• MgI2 (Magnesium Iodide)

3. What type of bond would these 2 atoms make? • Ionic since Magnesium is Metal and Iodine is a Nonmetal

Mg II

Covalent Bonding• Occurs between two nonmetals• Electrons are shared instead of being transferred

• Both atoms need to gain electrons, so they share the electrons they have.

• Atoms still follow the octet rule• No ionic charges or oxidation numbers

++

++

+

++++-

--

-

-

--

-

OH H

+-

-

Sharingelectron

Sharingelectron

• Electrons move back and forth between the outer energy levels of each atom.

• Each atom has a stable outer energy level some of the time.

• Atoms can share one, two, or three pairs of electrons.

How Covalent Bonding Works

Bonding Animation

BrainPop Bonding

Single Bonds Share 2

Electrons

Double Bonds Share 4 Electrons

Triple Bonds

Share 6 Electrons

+

++

+

+++

+++

-

-

-

-

-

-

-

-+

+-

-

+

+

++

+

+++

+++

-

-

-

-

-

-

-

+

++

+

+++

+++

-

-

-

-

-

-

-

+

++

+

+++

+++

-

-

-

-

-

-

-+

-

+

+

+

+++

+++

-

-

- -

+

++

+

+++

+++

-

-

-

--

-

-

-

+- -

Water (H2O)

Carbon Dioxide (CO2)

Nitrogen (N2)

Naming Covalent Compounds1 mono

2 di

3 tri

4 tetra

5 penta

6 hexa

7 hepta

8 octa

9 nona

10 deca

• Each element gets a “greek prefix”• Prefix refers to # of atoms in the

molecule• Change ending to “ide”

• Ex: N2O4 = dinitrogen tetroxide• The first vowel is often dropped to avoid

the combination of “ao” or “oo”.octaoxide = octoxide

• Exception: drop mono for first elementCO2 = carbon dioxideCO = carbon monoxide

NOW do you find this funny?!

Name these covalent compounds: CCl4 P2O3 IF7

•CCl4 = carbon tetrachloride

• P2O3 = diphosphorus trioxide

• IF7 = iodine heptafluoride

Try This:

Write the covalent compound formula: • Tricarbon pentoxide• Sulfur nonafluorine

• Tricarbon pentoxide = C3O5

• Sulfur nonafluorine = SF9

Try This:

Candy Bonds Activity

Today’s Agenda1. Candy Bonds activity2. Discuss/Correct HW worksheets from last week:

• Elemental Love Story• Naming practice

3. Complete Chapter 5 review worksheet• Check answers in back- flower folder

4. Share Answers to Candy Bonds

* If time: Draw Your Own- plain white paper

1. What type of bond occurs between a metal and a nonmetal? ionic

2. What type of bond occurs between a two nonmetals? Covalent

3. CaF2 Calcium fluoride (*ionic)

4. triphosphorus tetrabromide P3Br4

5. N5O9 Pentanitrogen nonoxide

Name these compounds: • CCl4 = carbon tetrachloride

• P2O3 = diphosphorus trioxide

• IF7 = iodine heptafluoride

Write these compounds: • Tricarbon pentoxide = C3O5

• Sulfur nonafluorine = SF9

Solutions:

What Kinds of Bonds are These?

Ionic BondingSodium Chloride = NaCl = Na+1 + Cl-1