The major assumption is that pairs of valence electrons repel each other.
Identify the major assumption of the VSEPR theory, which is used to predict the shape of atoms.
The lone pairs of electrons on oxygen make the molecular shape bent or angular.
In water, two hydrogen atoms are bonded to one oxygen atom. Why isn’t water a linear molecule
Electronegativity difference and molecular geometry
What two factors determine whether or not a molecule is polar?
The attraction between the ions and water molecules is weaker than the ion to ion attraction
Why are some ions non-soluble in water?
They move around freely because they are delocalized
What do valence electrons do in a metallic bond?
The ability for the electrons to move around freely
What is responsible for the good electrical conductivity of metals?
A compound with a charge
What is an ionic compound?
In what form do most ionic compounds occur?
The lowest whole number ratio of ions represented in an ionic compound
What is a formula unit?
What is energy released when one mole of an ionic crystalline compound that is formed from gaseous ions?
The higher the lattice energy the stronger the bond
In general, what is the relationship between lattice energy and the strength of ionic bonding?
Ionic bonds have higher melting point and boiling points; Ionic bonds don’t vaporize as easy
In general, how do ionic and molecular compounds compare in terms of melting points, boiling points, and ease of vaporization?
Ionic bonds are stronger, and covalent bonds are weaker than Ionic bonds; the difference in the properties tell us how strong the bonds are
What accounts for the observed differences in the properties of ionic and molecular compounds?
Ionic bonds are malleable, ductile, and brittle (Also conductive in liquid form)
Cite three physical properties of ionic compounds.
Multiple atoms together that have a charge
What is a polyatomic ion?
ClO₄⁻ and NH₄⁺
What are two examples of polyatomic ions?
They occur bonded to something.
In what form do polyatomic ions often occur in nature?
The notation for sodium chloride, NaCl, stands for one…?
In a crystal of an ionic compound, each cation is surrounded by a number of…?
The crystal lattice that results has lower potential energy.
Compared with the neutral atoms involved in the formation of an ionic compound, the crystal lattice that results has what?
It will be more difficult to break the bonds in compound A than those in compound B.
The lattice energy of compound A is greater in magnitude than that of compound B. What can be concluded from this fact?
The molecular forces of attraction are weaker than the attractive forces among formula units in ionic bonding.
What are the forces of attraction between molecules in a molecular compound generally?
The force that holds the ions together is the attraction between the oppositely charged atoms.
Describe the force that holds two ions together in an ionic bond.
What type of energy best represents the strength of an ionic bond?
Covalent bonds are inside the polyatomic ion, but the ionic compound is ionically bonded.
What types of bonds are present in an ionic compound that contains a polyatomic ion?
It states electron pairs move to make angles, and from the angles you determine shape and from there you classify the molecules
How is the VSEPR theory used to classify molecules?
What molecular geometry would be expected for F₂ and HF?
They take up more space and they repel more strongly.
Describe the role of the following in predicting molecular geometries: unshared electron pairs
They count as if they were a single bond
Describe the role of the following in predicting molecular geometries: double bond
The size of the ions.
What determines the shape of the crystal lattice structure?
Lattice energy is always being released.
Why does lattice energy always have a negative value?
When a force is applied, such as a hammer strike, the ions are rearrange so that ions of similar charge align (cation-with-cation, anion-with-anion). Similar charges repel, causing bonds to break.
Why are ions brittle?
Metals that are bonded to metals
What is a metallic bond?
“Electron Sea” structure
What kind of structure do metallic bonds have?
They have very high melting points, they are not soluble in water, they will conduct electricity in any form
What are some characteristics of metallic bonds?
Bonding pairs and lone pairs
What are the two types of electron pairs?
What is the molecular shape that has two bonding pairs and no lone pairs?
What is the molecular geometry shape that has three bonding pairs and no lone pairs?
What molecular shape has two bonding pairs and one lone pair?
What is the molecular shape that has four bonding pairs and no lone pairs?
What is the molecular shape that has three bonding pairs and one lone pair?
What is the molecular that shape has two bonding pairs and two lone pairs?
What is the molecular shape that has five bonding pairs and no lone pairs?
What is the molecular shape that has six bonding pairs and no lone pairs?
What is the bond angle of a linear shape?
What is the bond angle of a trigonal planar shape?
(Less Than 120)<120°
What is the bond angle of a bent/angular (AB₂E) shape?
What is the bond angle of a tetrahedral shape?
What is the bond angle of a trigonal pyramidal shape?
What is the bond angle of a bent/angular (AB₂E₂) shape?
What is the bond angle of a trigonal bipyramidal shape?
What is the bond angle of a octahedral shape?
The direction of the polar bond in a molecule
What is a dipole moment?
The most electronegative atom
To which atom will the dipole moment point to?
Dipole moments are symmetrical and cancel out
For nonpolar molecules dipole moments are what?
Dipole moments are assymmetrical and don’t cancel out
For polar molecules dipole moments are what?