Chemical Bonds
Define a chemical bond.
What is a force/mutual electrical attraction that holds atoms together in a substance?
Electronegativity is.
What is the measure of the ability of an atom in a bond to attract electrons?
Definition of molecule.
What is a neutral group of atoms held together by covalent bonds?
Definition of ionic compound.
What is formed when electrons are transferred from the cation to the anion?
Covalent compounds differ from ionic compounds.
Ionic bond =
Formed when electrons are transferred from the cation to the anion
Covalent compound =
A compound formed when two or more atoms share electrons
Octet rule
What is the tendency of atoms to prefer to have 8 valence electrons?
Electronegativity affects bonding.
What is when the electronegativity difference is small, and thus not big enough for one atom to take the electrons from the other, the atoms share instead in a covalent bond.
Definition of a covalent compound.
What is the bond between nonmetallic atoms that share electrons?
The significance of a chemical formula in ionic compounds.
What is the representation of the ratio of cations to anions in the crystal lattice?
The properties that make metals good conductors.
The “sea of e-” forms because metals like to form lattices, but they are often bigger so their orbitals overlap. They also have lower electronegativities so their attraction for electrons in a bond is lower.
Because of this, the electrons are delocalized, making them good at creating a flow of e- when conducting electricity.
The difference between ionic and covalent bonds.
Ionic Bonds -
Electrons are transferred
Typically between a metal and nonmetal
Always between ions
Can result in the formation of a salt
Crystalline solids
High melting and boiling points
Can conduct electricity when dissolved in water
Covalent Bonds -
Electrons are shared
Always between nonmetals
Can be polar or nonpolar
Results in the formation of a molecule
Can be solid, liquid, or gas
Low melting and boiling points
Cannot conduct electricity when dissolved in water
Example of a polar covalent bond.
What is H2O, the oxygen atom has a stronger attraction and pull on the electrons than the hydrogen atoms, and thus the oxygen side is a little more negative and the hydrogen side a little more positive, creating poles.
The difference between single, double, and triple bonds.
Single = 2 shared e-
Double = 4 shared e-
Triple = 6 shared e-
The properties of ionic compounds.
Electrons are transferred
Typically between a metal and nonmetal
Always between ions
Can result in the formation of a salt
Crystalline solids
High melting and boiling points
Can conduct electricity when dissolved in water
Alloys are important
Malleable (can be made into thin sheets)
Ductile (can be made into wires)
Can conduct electrical and thermal energy
Strong absorbers and reflectors of light
Why noble gases don’t form bonds.
What is noble gases don’t form chemical bonds because they are already stable?
The rule of zero charge
What is every time a metal atom and a nonmetal atom bond, they form a compound with an overall zero charge?
The factors determine molecular shapes.
VSEPR Theory,
The tendency for electron pairs to be as far apart as possible from one another because valence electrons are repulsed by each other. This gives the molecule a 3-dimensional shape.
Naming a compound with a transition metal.
What is the Roman numeral is necessary to indicate the charge of the metal ion?
The significance of delocalized electrons.
Electrons not associated with a single atom or bond
Because of this, the electrons are delocalized, making them good at creating a flow of e- when conducting electricity.
Bonding is a spectrum.
What is there aren’t just two types of bonds. It is a spectrum with ionic and nonpolar covalent at the two extremes.
Transition metals differ in electronegativity.
Metals that “transition” because they can form many different ions, you cannot determine the charge of a transition metal from the periodic table, so the Roman numeral is necessary to indicate the charge of the metal ion.
VSEPR theory.
VSEPR theory is the tendency for electron pairs to be as far apart as possible from one another, and thus when you draw Lewis structures for molecular compounds, you should draw them in a way that spaces them out as much as you can.
Examples of binary ionic compounds and their properties.
Binary ionic compounds: made of 2 elements that transfer e- in an ionic bond
Compounds with polyatomic ions: made of one (or more) covalently bonded charged group of atoms that transfer e- in an ionic bond.
Binary molecular compounds: made of 2 elements that share e- in a covalent bond
An example of a compound that has different properties than its elements.
NaCl = sodium chloride
Sodium on its own is extremely explosive when in contact with water.
Chlorine on its own is extremely poisonous.
Together they make table salt, which we can eat.