Unit 6 Review

Chemical Bonding Notes

Valence Electrons

• Recall: valence electrons are the electrons in the outermost energy level

• MOST IMPORTANT FOR BONDING

• Hydrogen and Helium only need 2 valence electrons in order to be stable

• The rest of the elements need 8

Why do elements bond?

• Full outer energy levels mean they are stable

• If the atoms of elements do not have full energy levels, they will seek out other atoms with whom they can join

• Elements will gain, lose, or share electrons to fill up the outer energy level (8 is the magic number) and become chemically stable.

Multiple Choice

Why do elements bond together?

• Because it is easier to survive in the world if they are bonded

• They share or transfer electrons to get a full outer shell to be happy

• They like to have a partner element to make them stronger

Octet Rule

• ›Atoms have the greatest stability (i.e. lowest energy) when they have 8 valence electrons

• ›Completely filled subshells

• ›No advantage to gaining or losing electrons

Octet Rule

• Atoms will gain or lose electrons to achieve a noble gas-like electron configuration

• They can also share electrons to achieve a stable octet

• 
  

Multiple Choice

How do atoms meet the octet rule?

• They lose or gain protons

• They lose or gain neutrons

• They lose or gain electrons in the outer most level

• They lose of gain electrons from the inner most level

Multiple Choice

According to the octet rule, atoms of elements react with each other in order to attain ____ electrons in their outermost energy level or shell.

• 2

• 4

• 6

• 8

• 10

Predicting Ion Charges

• Metals typically lose electrons

• Nonmetals typically gain electrons

Multiple Choice

Which of the following elements GAINS 3 electrons in order to attain an octet?

• nitrogen

• lithium

• boron

• oxygen

• fluorine

Multiple Choice

Which of the following elements LOSES 2 electrons in order to attain an octet?

• lithium

• magnesium

• helium

• sulfur

• bromine

Multiple Choice

What is the typical ion charge that forms when phosphorus forms an ion?

• +1

• +2

• -1

• -2

• -3

Multiple Choice

Which of the following elements GAINS 1 electron in order to attain an octet?

• sodium

• calcium

• helium

• boron

• chlorine

Multiple Choice

What is the typical charge when potassium forms an ion?

• +1

• +2

• +3

• -1

• -2

Noble Gases (Group 18)

• The Noble Gases already have full outer energy levels

• They are chemically stable and very rarely form compounds

Other Elements

• Other elements do not have 8 valence electrons

• They will form chemical bonds in order to become chemically stable.

Multiple Choice

Which elements on the periodic table do NOT bond?

• Group 1 Alkali metals

• All metals

• All nonmetals

• Noble Gases

Chemical Bond

• A chemical bond is the force of attraction between two different atoms

• Sometimes it can occur between two of the same atoms

Types of Bonds

• There are three types of chemical bonds:

• Ionic

• Covalent

• Metallic

• We will only concentrate on ionic and covalent bonds

Ionic Bonds

• A transfer of electrons from metals to nonmetals

• The smallest unit of the compound is the ion

• The bond occurs because of the attraction between the positive ion and the negative ion

• The compounds conduct electricity when dissolved in water

Covalent Bonds

• Sharing of electrons between nonmetals and metalloids

• The smallest unit of the compound is a molecule

• The bond occurs because the atoms must stay close together to share electrons

• The compounds do not conduct electricity well when dissolved in water

Refer to page 5 in your notes

Ions

• Charged particles resulting from a gain or loss of electrons

• Write the symbol of the element followed by a superscript indicating the oxidation number

Categorize

Options (8)

calcium

magnesium

beryllium

potassium

lithium

sodium

rubidium

aluminum

Place each element in the category of charge it will form when becoming an ion.

2+

1+

3+

Ionic Bonding

• Metals give up valence electrons so that the remaining energy level is full – they become positive ions (cations)

• Nonmetals gain valence electrons so that their outer energy level is full – they become negative ions (anions)

Compounds are neutral!

• The number of electrons lost by the metal must equal the number of electrons gained by the nonmetal

• The positive charge must equal the negative charge so that they cancel each other out

Multiple Choice

Which pair of atoms will form an ionic bond?

• Li and Ne

• K and Br

• K and Cs

• S and Cl

Multiple Choice

Which pair of atoms will form an ionic bond?

• Li and Be

• Na and Mg

• K and Ca

• Na and Cl

Multiple Choice

Which of the following compounds would you expect to be ionic?

• CO

• NaF

• CH4

• NH3

Multiple Choice

Which of the following compounds would you expect to be ionic?

• CO

• NO

• LiCl

• SiO2

Covalent Bonding

• Formed when atoms share electrons

• Occurs between two or more nonmetals or metalloids neither of which will easily give up electrons

• A molecule is a particle that forms from electron sharing.

Types of Covalent Compounds

• Polar compounds result from unequal sharing between atoms – one end of the molecule is slightly positive while the other end is slightly negative

• Made up of two atoms of unequal size

• Nonpolar compounds result from equal sharing between atoms – they have no electric charge

• Made up of two identical atoms or a symmetrical arrangement

Types of Covalent Bonds

• Single bonds: Two shared electrons Represented by a single line

• Double bonds: Four shared electrons Represented by two lines

• Triple bonds: Six shared electrons Represented by three lines

Multiple Choice

How many electrons do double bonds share?

• 2

• 4

• 6

• 8

Covalent Bonds involve nonmetals only.

...Who are the Nonmetals again?

Elements to the right of the staircase line AND Hydrogen , H

Categorize

Options (10)

Sodium (Na)

Chlorine (Cl)

Phosphorus (P)

Krypton (Kr)

Selenium (Se)

Bromine (Br)

Potassium (K)

Aluminum (Al)

Tin (Sn)

Strontium (Sr)

Organize these options into the right categories

Metals

Nonmetals

Multiple Choice

Magnesium (Mg) and Oxygen (O) form an ________ bond.

• Ionic
• Covalent
• Metallic
• Nothing

Multiple Choice

Valence electrons are transferred

• Ionic bonds

• Covalent bonds

Multiple Choice

Valence electrons are shared

• Ionic bonds

• Covalent bonds

Multiple Choice

Sodium and Bromine will make a _____ bond.

• ionic

• covalent

• metallic

Multiple Choice

Carbon and Oxygen will make a ___________ bond.

• ionic

• covalent

• metallic

Multiple Choice

MgO

• ionic

• covalent

• metallic

Multiple Choice

NaCl

• ionic

• covalent

• metallic

Multiple Choice

Hydrogen and Chlorine will from a _________ bond

• ionic

• covalent

• metallic

Multiple Choice

Which of these element pairs would bond covalently?

• Fr and K

• Sc and O

• F and Cl

• He and Pt

Multiple Choice

Which of the following is an example of a COVALENT COMPOUND?

• H₂S
• KI
• CaCl₂
• MgO

Multiple Choice

Which of the following is an example of an IONIC COMPOUND?

• NaCl
• H₂O
• CO₂
• NO

Multiple Choice

Al₂S₃

• covalent

• ionic

Multiple Choice

SrO

• covalent

• ionic

naming covalent compounds

Refer to page 3 in your notes for naming covalent compounds

Multiple Choice

Which of the following is the correct way to write: CF₄

• monocarbon tetrafluoride

• carbon fluoride

• carbon tetrafluoride

• monocarbon fluoride

Multiple Choice

Which of the following is the correct way to write: ClO₂

• monochlorine dioxygen

• monochlorine dioxide

• chlorine monooxide

• chlorine dioxide

• monochlorine oxide

Multiple Choice

Which of the following is the correct way to write: PCl₃

• monophosphorus trichlorine

• monophosphorus trichloride

• phosphorus trichlorine

• phosphorus trichloride

• triphosphorus chlorine

Multiple Choice

Which of the following is the correct way to write: CH₄

• tetracarbon hydride

• carbon tetrahydride

• monocarbon tetrahydride

• monocarbon tetrahydrogen

• triphosphorus chlorine

Multiple Choice

Which of the following is the correct way to write: Si₂F₈

• silicon octafluoride

• octasilicon difluoride

• disilicon octafluoride

• disilicon fluoride

• disilicon octafluorine

Refer to page 8 in your notes for writing ionic formulas

​Writing Ionic Formulas

​

• After identifying the reaction as an ionic compound between a metal and a nonmetal to write the formula:

  • Identify the ionic charge (charge of each element) 

  • Drop and swap the charges writing them as subscripts. 

​

• If the charges are equal and opposite (Neutral - Na +1, Cl -1; Ca +2, O -2; Al +3, P -3) there is no subscripts required for that reaction since the ratio would be 1:1 / 2:2 / 3:3.

​If the ionic charges are not equal and opposite we use the drop and swap method to identify the number of subscripts for each element.

​

Ionic Bonding:

Drop + Swap​

Multiple Choice

Creating an ionic compound:

What are the ionic charges for Calcium and Cl?

• Ca +1

  Cl -2

• Ca -1

  Cl +2

• Ca -2

  Cl -2

• Ca +2

  Cl -1

Multiple Choice

Creating an ionic compound:

What formula is created when Calcium and Chlorine form an ionic bond?

• CaCl

• CaCl₂

• Ca₂Cl

• Ca₂Cl

Multiple Choice

The formula for the ionic compound between Mg and S is:

• Mg2S2

• MgS

• MgS2

• SMg

Multiple Choice

The ionic compound formed between Ca and N is:

• CaN

• Ca2 N2

• Ca3 N2

• Ca2 N3

Multiple Choice

The ionic compound formed between Al and O is:

• Al3O2

• Al2O3

• AlO

• Al2O2

Multiple Choice

What is the ionic compound formed between P and Br?

• P3Br

• BrP

• This compound is not considered ionic

• (BrP)2

Multiple Choice

What is the ionic compound formed between Ca and Al?

• CaAl

• Ca3Al2

• Al2Ca3

• None of the above