Chapter 16.1 Test Flashcards
What is a covalent bond?
When atoms share electrons to become stable
What rule do covalent bonds follow in order to become stable?
Octet Rule
What are covalent bonds usually formed by?
It is formed between 2 nonmetals
What is the difference between ionic and covalent bonds?
Ionic bonds transfer electrons from metals to nonmetals to form ions. Covalent bonds share electrons between nonmetals.
What do covalent bonds form?
Molecules
What is formed when two or more atoms share covalent bonds?
molecular compound
What is a Single Covalent Bond?
One pair of electrons is shared between two nonmetal atoms
What is a structural formula?
A chemical formula that shows the arrangement of atoms within a molecule or polyatomic ion.
What is a molecular formula?
Tells us which elements and how many atoms of each element are in one molecule
What are molecular orbitals?
When atomic orbitals overlap in covalent bonding
What are unpaired electrons?
Usually the only valence electrons involved in bonding
What are unshared pairs?
The pairs of valences that aren’t shared between atoms and not usually involved in bonding.
What is an orbital diagram?
A diagram that indicates where electrons overlap in orbitals.
What is a molecule?
A neutral group of covalently bonded atoms that act as a single unit.
What is the representative for a molecular compound?
molecule
What is a double covalent bond?
When two pairs of electrons are shared between two nonmetal atoms.
What is a triple covalent bond?
When three pairs of electrons are shared between 2 nonmetal atoms.
What is another name for a chemical formula for a molecular compound?
molecular formula
What are molecular compounds a collection of?
molecules
Why don’t ionic compounds have molecular formulas?
They do not contain molecules
What is a diatomic molecule?
When written, they are added as two atoms.
What are the diatomic molecules?
- H
- N
- O
- F
- Cl
- Br
- I
How many diatomic molecules are there?
7
What is the Binary Molecular Compound?
A compound that contains two different nonmetal elements.
What is the main rule when diagramming molecular compounds?
The solitary atom will be the central atom and all other atoms will bond to it.
What are hydrocarbons?
Compounds that contain both H and C
What are alkanes?
They end in -ane, only have H and C in them and all have single covalent bonds between the carbons.
What are alkynes?
They end in -yne, triple covalent bond between carbons.
What is a coordinate covalent bond?
When one atom contributes both electrons to the bonding or shared pair
What are coordinate covalent bonds common in?
polyatomic ions
What are polyatomic ions?
A group of covalently bonded atoms with a charge that act as a single unit.
What is the first step when drawing covalent bonds with a Lewis Dot Diagram?
Determine the sum of each atom’s valences
What is the second step when drawing covalent bonds with a Lewis Dot Diagram?
Draw a skeleton structure, which means one bond between all bonding atoms
What is the third step when drawing covalent bonds with a Lewis Dot Diagram?
Subtract the total number of electrons involved in the bonds from the total number of valences from step 1.
What is the fourt step when drawing covalent bonds with a Lewis Dot Diagram?
Divide remaining electrons by 2 to determine the number of pairs to be placed around the electrons.
What is the fifth step when drawing covalent bonds with a Lewis Dot Diagram?
Place pairs of electrons on most electronegative atoms first and work from outwards in.
What is the sixth step when drawing covalent bonds with a Lewis Dot Diagram?
If needed, move pairs of atoms to form bonds to complete each atom’s octet.
When is there an exception to the Octet Rule?
If there is an odd total number of electrons
What are Resonance Structures?
More than one valid diagram for the same molecules
What are the original Lewis structures contributed by?
resonance structure
What are nonpolar bonds?
Electrons are shared evenly
What are polar bonds?
Electrons are shared unevenly
What is the main factor that determines polar vs. nonpolar bonds?
EN
Why do only nonmetals form covalent bonds and both kinds form ionic bonds?
Nonmetals electronegativity is closer and metals are weak, so the nonmetals share because both are pulling.
What is the rule to determine if a bond is nonpolar?
If the difference in EN between bonding atoms is 0 to 0.4, the bond is nonpolar.
What is the rule to determine if a bond is nonpolar?
If the EN difference between bonding atoms in 0.4 to 2.0, the bond is polar.
What kind of bond forms if the EN difference is over 2.0
ionic
How do you assign partial charges?
By using the difference in EN between bonding atoms to determine if bonds are polar or nonpolar and to determine an atom’s net charge.
What is a sigma bond?
A bond formed along the nuclear axis
What are rules for sigma bonds?
The nuclear axis is the shortest distance between two atoms and you can only have one bond per pair of electrons.
What are pi bonds?
They form above and below the nuclear axis
Which are stronger sigma or pi bonds?
sigma.
What is the structure of a molecular compound?
Crystal structure
What is a molecular compound’s property of solubility in water?
High to low, variable solubility
Do molecular compounds conduct electricity as solids?
No
Are molecular compounds flammable?
Some are, some are not
What is a molecular compound’s property of melting point?
Generally low melting points
What is solubility’s relationship with temperature in molecular compounds?
As one increases, the other increases
Do molecular compounds conduct electricity in solutions?
No
