Unit 2.1: Lewis Dot Structures and Ionic Bonding.

Unit 2.1: Lewis Dot Structures and Ionic

Bonding

Bell Work October 6

Agenda:1.Turn in Test Corrections and anything you forgot to turn in while I was gone2.Planner: No Homework3.Notes4.Lewis Dot Structure Activity

Bell Work:

•Write down 2 things you learned while I was on Outdoor Ed.

•My Favorite Demonstration of All Time

Chemical Reactions

• When substances react and new substances form• Chemical Bond: the force of attraction that holds two atoms together as

a result of the rearrangement of electrons between them.• When atoms bond, electrons may be transferred from one atom to

another or shared between the atoms. • Chemical Reactions are shown with chemical equationsChemical Reactions Video

Chemical Equations

• Show the rearrangement of atoms to form new substances in a chemical reaction• Example:

• CH4 + 2O2 CO2 + 2H2O

• Reactants: The substances that react; what you start with (left side of arrow)• Products: The substances that are produced; what you make (right side

of arrow)

Reading a Chemical Equation

• CH4 + 2O2 CO2 + 2H2O• CH4: Methane• O2: Oxygen• CO2: Carbon Dioxide• H2O: Water

• “Methane and oxygen react to form carbon dioxide and water”• + : “and”• : “react to form”• Coefficients are the number of molecules of each substance

Valence Electrons

• Electrons in the outermost shell of an atom• Atoms can give away, take away, or share

electrons to get to 0 or 8 valence electrons• Remember, they want an empty or full

valence shell, if they don’t have one then they are unstable (HAPPY OCTOPUS!)

Lewis Dot Structures of Elements• Lewis Dot structures are used to show valence

electrons• Can be helpful when predicting how elements bond• Rules:

• Look on the periodic table to determine how many valence electrons are in an element

• Write the symbol of the element• Imagine that the element is in a box with 4 sides• Start on top and rotate clockwise putting one dot (electron)

at a time• Continue to circle, double electrons when needed. • Do not add more than 2 electrons to each side

Write the Lewis Dot Structure for the following Elements:

• Lithium (Li):

• Aluminum (Al):

• Bromine (Br):

Bell Work October 7

Agenda:1.Turn in Article and Article Summary2.Planner: Lewis Dot Structure of Ionic Compounds3.Lewis Dot Structure Activity4.Notes

Ions1. An Ion is a charged particle2. The number of electrons is NOT equal to the

number of protons3. Atoms become charged particles when they

gain or lose electrons

Cations and Anions

Naming Ions

What type of Ions do each group form?• Remember, elements are lazy, they do whatever is easiest• They want to either gain or lose electrons to get to 0 or 8 valence

electrons• Example:• If I have 1-3 valence electrons, it is easier to lose electrons than to gain them• If I have 5-7 valence electrons, it is easier to gain electrons than to lose them• IF I have 4, I could go either way

Bell Work October 8

Agenda:1.Planner: Lewis Dot Structure of Ionic Compounds2.Notes3.Lewis Dot Structure of Ionic Compounds 4.Notes5.Lattice Structure Activity6.Notes

Bell Work:•Label the following as a metal or a nonmetal. Label if it will form a cation or an anion.• N• Al• F• Li

Ionic Charges

• Atom gaining electrons = anion• Adding a negatively charged particle makes the atom more negative

• Atoms losing electrons = cation• Taking away an electron means you take away something that is negative. This

makes the atom more positive

• Example:• Negative people in your life will make you more negative• If you get rid of this negative person, then you will be happier or more positive

Ions form Ionic Bonds

• Electrons are TRANSFERRED from one atom to another to form ions• This creates a negatively charged ion (anion) and a

positively charged ion (cation)•Opposites attract, the anion is attracted to the cation,

this creates an IONIC BOND•Dogs Teach Bonding Video

Ions form Ionic Bonds

•Transfer of electrons from metals to nonmetals•All Ionic Bonds are called “Salts”•Ionic Bonds are weak, compared to other types of bonds•Bond between METAL and NONMETAL

Lewis Dot Structures of Ionic Compounds

• Na + Cl

• K + F

• Be + I + I

Properties of Ionic Bonds

• Solubility: the ability to dissolve in a solvent (typically water, but can include other liquids such as alcohols)•Conductivity: describes if a substance can carry

electric current•Melting Points: temperature at which compounds

melt (Celsius)

Crystal Lattice

• Styrofoam Ball Activity

•Positive ions (cations)

are attracted to

negative ions (anions)

Solubility

• Solubility: Ability to dissolve in a solvent• Insoluble: Not Soluble (Does not dissolve)• Partially Soluble: Only partially dissolves• Ionic compounds tend to dissolve well in water or alcohol but not in

things like oil

Solubility

•When ionic compounds dissolve, they are pulled out of their lattice structure and into their ionic state•Dissociation: when ionic compounds are pulled into their ions and out of their lattice structure• Ionic Dissociation Animation

Conductivity

• Conductivity: The ability to conduct electricity• Ionic compounds are not conductive in their solid state• They are conductive in their liquid state because the ions are

dissociated• Aqueous: Dissolved in water• Electrolyte an aqueous salt solution• Conductivity Animation

Melting Point

•Melting Point (MP): temperature at which compounds melt•Melting Points are extremely high for ionic compounds due to their lattice structure and the strength of their bond

Flame Test

•Metals turn a very specific color when exposed to flame if they are in an ionic compound•Every metal has it’s own specific color•You can identify an unknown metal by the color of the flame•They use this for fireworks!