Chapter 5: Molecular & Ionic Compounds

The Octet Rule When atoms bond, they tend to gain, lose, or share electrons to result in having 8 valence electrons. • Exception to The Octet Rule: 1) Species with an _____________________ (Radicals). 2) Species with _________ octet (_________________). H and He are duets (though H can lose 1 e-). -Li loses 1 valence electrons. -Be loses 2 e- and/or share 2 to have 4 valence e-. -B loses 3 e- and/or share 3 to have 6 valence e-

1. odd # of electrons 2. incomplete octet ( less than 8 electrons)

Polarity of Molecules • Important: In order for a molecule to be polar it must: 1. Have _________________________. -Electronegativity difference between 0.5-2.0 -Bond dipole moments. 2. Have ______________________________. __________________________. Results from unsymmetrical shapes. • Polarity affects the intermolecular forces of attraction. Therefore boiling points and solubilities

1. at least 1 polar bond 2. Unequal electron pulls unequal electron sharing

Oxyanions Some common polyatomic ions

Acetate, Carbonate, etc memorize the

Lewis Theory and Covalent Bonding In Lewis theory: We represent covalent bonding by allowing neighboring atoms to share some of their valence electrons in order to attain octets (or duets). _______________: Refers to electrons in a bond. ______________: Refers to electrons not in a bond. _________ Covalent Bond: Two atoms share one pair of electrons Each line ( bond) is equal to 2 valence electrons

Bonding pair Lone Pair [Means that there are 2 (**) dots or 2 VE that are not in a bond (-) ] Single

Ionic Compounds Ionic compounds always contain _________ and __________. No individual molecule unit exist, instead they have a 3-dimensional array of cations and anions made of ________________________. • Formula Unit (Chemical Formula): Is the simplest representative particle of an ionic compound

Cation + Anion formula units

Classifying Materials: Molecular & Ionic Compounds _____________: Are substances composed of 2 or more different types of atoms in fixed proportions. Compounds can be classified as: 1) _____________ Compounds: Are composed of nonmetals only. ____________ Bonding. 2) ____________ Compounds: Are composed of cations (+) and anions (-). _________ + _________. ___________ Bonding. (https://youtu.be/1zCuTL81FVU)

Compounds Molecular Covalent Ionic Metal + Nonmetals Ionic

Molecular Compounds Are compounds whose particles are molecules made of only nonmetals. Covalent Bond. • __________ Bonding: Is the sharing of valence electrons between nonmetal atoms to attain a noble gas arrangement ( most stable because of the 8 valence electrons)

Covalent

• Lewis Theory and Covalent Bonding ________ Covalent Bond: Two atoms share two pairs of electrons. _______ Covalent Bond: Two atoms share three pairs of electrons

Double Triple

VSEPR Theory • Important: Counting electron groups around the central atom. 1. _______________ of electrons constitutes one electron group on a central atom. 2. ______________ (as in radicals) will constitute one electron groups on a center atom. 3. ______________ constitutes one electron group on a central atom. - Regardless of whether it is single, double, or triple.

Each lone pair Single electrons Each bond

Polarity of Molecules • Important: Summarizing molecular shape and polarity. 1. Draw the Lewis structure for the molecule and determine its _____________ geometry. 2. Determine if the molecule contains _____________. 3. Determine if the electrons are being shared ________________

Electron polar bonds unequally

Classifying Materials • _________: Are substances that cannot be broken down to simpler substances by chemical reactions. • Elements can be classified as: 1) _________ Elements: Elements whose particles are single atoms. Most elements. 2) ___________ Elements: Elements whose particles are multi-atom molecules. Elements that exist as diatomic units: 118 elements in Periodic Table; 109 are atomic; 7 of 9 molecular elements are diatomic.

Elements Atomic ( 1 type of atom) Molecular ( multi-atomic)

Hydrogen Bonding • Definition: Is the interaction between _______________ bonded to __, __, or __ and a lone pair on __, __, or __. The ____________ among Dipole-Dipole forces

Hydrogen atoms F, O, N and lone pair on F, O, or N Strongest

Molecular Elements Diatomic Elements ( Rule of 7) Have No Fear of Ice Cold Beer

H₂ N₂ O₂ F₂ I₂ Cl₂ Br₂

Electronegativity • Is the measure of the pull an atom has on bonding electrons. ____________ from left to right across a period. ___________ from top to bottom down a column

Increases Decreases (Flourine has the most electronegativity)

• _____ Bond: Is the transfer of electrons between 2 atoms. _______ + _________. • _________ Bond: Is the sharing of electrons between nonmetal atoms to attain a noble gas arrangement. _________ + ___________. Not necessarily equal sharing

Ionic Metal + nonmetal Covalent Nonmetal + Nonmetal

Dipole and Bond Polarity • Dipole Moment: Is the direction of the electron flow that results from polar covalent bonds. ______________________________

Is a measure of bond polarity -Starts from least electromagnetic to more electromagnetic

Predicting Molecular Shapes • Important: To predict the molecular shapes around the central atom: 1. Draw the correct __________________. 2. Determine the number of _______________ around the central atom. 3. Classify each electron group as bonding or lone pair, and count each type. 4. Use VSEPR summary table to determine the shape and bond angles

Lewis structure Electron Groups

Solubility and IMFs • Important: Solubility depends, in part, on the IMFs between the solute and solvent molecules. ________________________. Polar molecules dissolve in _______ solvents. Nonpolar molecules dissolve in __________ solvents

Like Dissolves Like Polar Nonpolar

Molecular Polarity Affects Solubility • Important: Polar molecules are attracted to other polar molecules, and nonpolar to nonpolar molecules. ________________________! • Since water is a polar molecule, other polar molecules dissolve well in water. _________________ as well. • Polar and nonpolar molecules do not dissolve in each other. Because they have different ________________________

Like dissolves like Ionic Compounds Intermolecular forces

Types of Chemical Formulas • __________ Formula: Gives the actual number of atoms of each element in the molecule of a compound. • _____________ Formula: Gives the relative number of atoms of each element in a compound. Simplest whole number ratio between atoms. • __________ Formula: Uses lines to represent covalent bonds and shows how the connectivity of atoms

Molecular Empirical ( Like a Surname.. Categorizes the type of family the compound is..) Structural ( Like the Lewis Structure or VSEPR theory)

__________: Are composed of 2 or more atoms bonded together. Composed of identical as well as different atoms. The fundamental unit of compounds. __________: Are composed of 2 or more atoms bonded together. Composed of identical as well as different atoms. The fundamental unit of compounds.

Molecules Compounds Note!: ALL Compounds are molecules but NOT ALL Molecules are Compounds.

The Order of Atoms in Formulas Metals are written first, then non-metals. In compounds that do not include a metal, the more metal-like element is listed first. Nonmetals are written with the most to the left of periodic table 1st, (H is the exception). NO2 or O2N? Nonmetals are written with the farther down of the periodic table 1st. SO2 or O2S?

NaCl or ClNa?

The System of Naming Compounds • _________________: Is a systematic method for naming compounds. • IUPAC Nomenclature: Is the official international system for naming chemical compounds. International Union of Pure and Applied Chemistry. • Each category of compounds has a specific naming system. _________ Compounds. ____________ Compounds. _______ (Ch 10)

Nomenclature Ionic Molecular Acids

Bond Polarity • Note: Due to bond polarity, there are 3 types of bonds: 1. ___________ Is an equal or almost equal sharing of electrons by two bonding atoms. -Electronegativity difference (0-0.4). 2. ___________ : Is an unequal sharing of electrons. -Electronegativity difference (0.5-2.0). 3. ___________ : Is a result of electron transfer. -Electronegativity difference (greater than 2.0)

Nonpolar Covalent Polar Covalent Ionic

Naming of Oxyanions • Oxyanions: Are polyatomic ions containing Oxygen with other elements. Also called: Must memorize the -ate ions

Oxoanions

Bonding Theories • Question: Why study bonding theories? - Explain how and why atoms attach together to form molecules. -Explain why some combinations of atoms are stable and others are not. -Why water is H2O and not H3O. • Bonding theories can be used to predict the ________ of molecules, which in turn determine many of their ___________ and __________ properties. • Let's talk about bonding to understand shapes to determine properties of molecules

Shapes chemical physical

Steps to determine the total number of each type of atom in a chemical formula

Step 1: Write the chemical formula Step 2: List all the atoms Step 3: Count the number of atoms of each element in 1 molecule. Step 4: Multiply the number of atoms of each by the coefficient. Step 5: Make sure your answer makes sense

Electron Geometry: 4 E. G. • Important: 4 electron groups will occupy positions in the shape of a tetrahedron around the central atom. • This results in the electron groups taking a ___________ geometry bond angle is___________

Tetrahedral 109.5 degrees

Derivatives of Tetrahedral • Important: 4 electron groups around the central atom with 1 being a lone pair results in a _________________ molecular shape. • The bond angle is __________

Tetrahedral pyramidal 109.5

Derivatives of Tetrahedral • Important: 4 electron groups around the central atom with 2 being lone pairs result in a ___________________ molecular shape. • The bond angle is ____________

Tetrahedral-Bent less than 109.5 * Lone pairs have more EN force so it pulls the angle in tighter.

Gaining and losing electrons

The # of electrons lost or gained is relative to how far away it is from becoming most stable; being like noble gases with 8 valence electrons.

Monatomic Cations • Type ___ Cations: Metals that form a cation with always the same/ Fixed charge. All main group cations (except for ______________), plus _____, _____, & _____. • Type ____ Cations: Metals that form a cation with different charges. All transition metals (except ___, ____, & ____), plus _______________

Type I (Heavy Metals), plus Zn²⁺, Cd²⁺, Ag⁺ ( AKA Group 1A, Group 2A and Magic triangle) Type II (Zn²⁺, Cd²⁺, Ag⁺ ) plus Heavy Metals

Naming of Monatomic Cations • Important: Name monatomic cations as follows. ________ Cations: NO need to indicate the charge. ________ Cations: NEED to indicate the charge. The charge is specified by Roman numerals.

Type I Type II

Lewis Bonding Theory • _____________________: Are the electrons that exist in the outermost energy level. ________________: Are those in lower energy levels. • The group number (________________) gives the number of valence electrons for the elements in those groups. • Chemists have observed that one of the most important factors in the way an atom behaves, both chemically and physically, is the number of valence electrons

Valence Electrons Core Electrons Main Groups 1A-8A

Lewis Bonding Theory • Lewis theory emphasizes ______________ to explain bonding. • Using Lewis theory, we can draw models called Lewis structures or dot structures. • Lewis structures represent valence electrons as dots surrounding the symbol of the element. • Lewis structures allow us to predict many properties of molecules such as _________________, ______, _____, and _____________

Valence Electrons molecular stability, shape, size, and polarity

Intermolecular Forces (IMFs) • Definition: Are the forces of attraction that exist between molecules. • Why study IMFs? They are directly related to properties such as ______ point, _____ point, and the energy needed to convert a solid to a liquid or liquid to a vapor. -They are important in determining the solubility of gases, liquids, and solids in various solvents. -They are crucial in determining the structures of important molecules such as DNA and proteins

boiling point, melting point,

Formulas of Ionic Compounds In chemical formulas, the sum of the ______ charges must equal the sum of the _______ charges. Subscripts must be the smallest whole number ratio. If you have more than one polyatomic ion, place it in parenthesis with the needed subscripts outside

cation anion

Formulas of Ionic Compounds • Important: When writing formulas for ionic compounds, apply the ____________. Charge on cation becomes the subscript on anion. Charge on anion becomes the subscript on cation. If subscripts are not in the lowest whole-number ratio, divide them by the biggest common factor

cross rule

The properties of a compound are ________ from the properties of the elements that compose it.

different

Molecular Geometry • Important: Counting the electron groups will give the __________ shape, while the number of bonded vs. non- bonded groups will give the _____________ shape. • The molecular geometry may be different from the electronic geometry if: -The electron groups are attached to atoms of different sizes. -The bonding to one atom is different than the bonding to another atom (single, double, or triple bonds). -There are lone pairs "they occupy more space"

electron molecular

Lewis Structures of Molecules • Important: Steps of drawing Lewis structures for molecular compounds. 1. Write the skeletal structure with the least Electonegative atom at the center (_______) singly bonded to terminal atoms. Typically put the single element in the middle.. 2. Determine total number of valence electrons (include any overall charges) and subtract electrons used in skeletal structure. 3. Distribute remaining electrons on terminal atoms ( outer atoms 1st, central atom gets whats leftover and then you can determine double bond etc.) fulfilling their octets (or duet in the case of H). EACH element Needs 8 VE but each of the bonds acts as 2 VE and counts for each individual element. Think of it as borrowing the VE when they need it. 4. Give extra electrons to central atom. 5. If any atoms lack octet, form double or triple bonds as necessary to give them octets https://youtu.be/cIuXl7o6mAw

except for H

The Octet Rule When atoms bond, they tend to gain, lose, or share electrons to result in having 8 valence electrons. • Exception to The Octet Rule: 3) Species with ________ octet (__________________). -Elements in period 3 or below can open d orbitals. -Beyond mentioning them, we do not cover expanded octets here

expanded octet ( more than 8)

Naming of Monatomic Anions The Nonmetal anion are named by dropping the end of the element name and substituting with suffix "-_____".

ide

Most substances we encounter in everyday life are compounds (not free elements). Free elements are rare in nature. (More stable when in a compound form; like a relationship) A compound is different from a mixture of elements. In a mixture, elements have __________ proportions. In a compound, elements combine in fixed, definite proportions (The Law of ______________________).

indefinite definite properties

Ion-Dipole Forces aka Strongest • Definition: Are the interactions between ______ and molecules with __________________ (polar molecules)

ions permanent dipoles

The Law of Definite Proportions • Definition: All samples of a given compound have the same proportions of their constituent elements. Mixtures have _______________ composition

variable

Dispersion Forces • Important: Factors that influence Dispersion Forces. 1. A __________ electron cloud, the ___________ the dispersion force. 2. The __________ the molar mass for elements within the same family, the _________ the dispersion force

larger, greater Bigger, greater

Electron Geometry: 2 E. G. • Important: 2 electron groups will occupy positions on opposite sides of the central atom. • This results in the electron groups taking a ___________ geometry. • The bond angle is ________.

linear 180

Lewis Theory and Ionic Bonding • In Lewis Theory: The transfer of electrons is represented by moving electron dots from the metal to the nonmetal. • Cations have Lewis symbols without valence electrons. -Valence electrons _______ in the cation formation. • Anions have Lewis symbols with 8 valence electrons. Valence electrons _________ in the formation of the anion.

lost gained

Lewis Bonding Theory • Premise: Atoms bond because it results in a more stable electron configuration. More stable means _________ potential energy. • Atoms bond together by either transferring (____ bond) or sharing electrons (___________ bond). • Usually this results in all atoms obtaining an outer shell with 8 electrons. ____________________. The octet rule generally applies to all main-group elements except ________, ________, __________, ___________, and _________

lower Ionic Covalent Octet Rule hydrogen, helium, lithium, beryllium, boron ( Elements 1-5 because they are trying to be most like the noble gas H and He only has 2 valence electrons.. not 8!)

Why do Atoms Bond? Atoms bond to _____ their ______________. - Chemical bonds form when the ________________ of ______ atoms are _____ than the ________________ of ___________ atoms. • _____________: Are the attractions between atoms, ions, or molecules that result in the formation of compounds. • We can classify bonds based on the kinds of atoms that are bonded together

lower their energy potential energy bonded less than potential energy separate Chemical Bonds

Dipole-Dipole Forces • Definition: Are the interactions between molecules with _____________________ (polar molecules). The (+) end of one molecule will be attracted to the (-) end of another

permanent dipoles

Polarity of Molecules • Example: Is CO2 polar? The O-C bond is ________. The bonding electrons are pulled equally toward both O ends of the molecule. The net result is a ___________ molecule

polar nonpolar

Polarity of Molecules • Example: Is HCl polar? The H-Cl bond is _________. The bonding electrons are pulled toward the Cl end of the molecule. The net result is a ________ molecule

polar polar

Chemical Formulas with Polyatomic Ions Important: Some chemical formulas contain groups of atoms that act as a unit. Many of these groups of atoms have a charge associated with them and are called ______________. If more than one of the same polyatomic ion is present, their formula is placed in parentheses with a subscript to indicate the number of that group

polyatomic atoms

Resonance Structures • Definition: Are two or more structures of the same molecule that differ only in the position of the electrons. Delocalization of electrons helps ________ molecules. • The actual molecule is a combination of the resonance forms (A resonance hybrid)

stabilize

Intermolecular Forces (IMFs) • Important: The strength of IMFs in a substance determines the state of matter (solid, liquid, or gas). -At a given temperature. -The ________ the IMFs, the ______ the melting. point. & boiling. point. The ________ the IMFs, the_______ the m. p. & b. p. • We will study four types of IMFs. 1) ______________ Forces. 2) ______________ Forces. 3) ____________________. 4) ______________ Forces

stronger higher weaker lower Ion-Dipole Dipole-Dipole Hydrogen Dispersion

Chemical Formulas • Definition: Indicate the elements present in a compound and the relative number of atoms of each. • The formula contains the symbol for each element, accompanied by a __________ indicating the number of atoms of that element. If there is only one atom, a subscript of 1 is omitted

subscript

Electron Geometry: 3 Electron Groups. • Important: 3 electron groups will occupy positions in the shape of a triangle around the central atom. • This results in the electron groups taking a _________ ___________ geometry. • The bond angle is ________

trigonal planar 120

Derivative of Trigonal Planar • Important: 3 electron groups around the central atom with 1 being a lone pair results in a _________________ _________ molecular shape. • The bond angle is __________

trigonal planar Bent 120