3B1 Bonding Flashcards
Compare ionic, covalent, and metallic bonding in terms of bond strength, length, and polarity.
Define:
electronegativity
The attraction of atoms to electrons.
More electronegative atoms pull shared electrons closer, creating dipoles.
List the two main types of covalent bonds based on electronegativity.
- Polar covalent bonds
- Non-polar covalent bonds
Polar bonds have uneven electron sharing, while non-polar bonds share electrons evenly.
List the three types of covalent bonds based on the number of electron pairs shared.
- Single covalent bond
- Double covalent bond
- Triple covalent bond
Single bonds share one electron pair, double bonds share two electron pairs, and triple bonds share three electron pairs.
List the two categories of electrons in an atom.
- Core electrons
- Valence electrons
Valence electrons are those in the outermost energy shell.
Core electrons are not involved in bonding, while valence electrons are used in chemical bonding.
Define:
ionic bonding
Bonding that occurs when one atom donates electrons to another, creating oppositely charged ions that attract each other.
Ionic bonds involve complete transfer of electrons.
What is the role of metals in the formation of ionic compounds?
They donate electrons to form cations.
Metals have low electronegativity and prefer to lose electrons.
What do nonmetals do during the formation of ionic compounds?
They receive electrons to form anions.
Nonmetals typically have high electronegativity and prefer to gain electrons.
What structure do ionic compounds form?
Crystal lattice structure.
This structure is a rigid and has ordered arrangement of ions. An example includes sodium chloride (NaCl).
Define:
lattice energy
Energy released when oppositely charged ions form a crystal lattice.
It represents the energy required to separate one mole of ions.
How does the lattice energy of an ionic compound affect its properties?
Higher lattice energy increases:
- Melting point
- Boiling point
- Hardness
Lattice energy is proportional to the charge and inversely proportional to the ionic radius.
What happens when a solid ionic compound is placed in water?
It dissolves into ions.
Water’s polarity helps to separate the ions, forming an aqueous solution.
Fill in the blank:
Ionic compounds when melted or in solution are good _______.
Conductors of electricity.
The mobility of ions in solution or molten form allows for electrical conductivity.
What is the effect of ionic charge on the structure of ionic compounds?
Holds ions in a rigid arrangement.
Positive ions align with negative ions in a strict fashion.
Why are ionic bonds strong?
Due to the electrostatic force between oppositely charged ions.
This force is proportional to the charge and inversely proportional to the distance between ions.
How does the charge of ions affect ionic bond strength?
Higher charges result in stronger ionic bonds.
For instance, MgO (Mg²⁺ and O²⁻) has stronger bonds than NaCl (Na⁺ and Cl⁻).
List three properties of ionic compounds.
- High melting and boiling points.
- Soluble in water.
- Good conductors in molten or aqueous states.
High melting and boiling points arise from strong electrostatic forces between ions.
Why are ionic compounds brittle?
The rigid lattice structure causes the compound to shatter when force misaligns the ions.
Misalignment brings like charges close together, resulting in repulsion and breakage.
True or False:
Ionic compounds are generally polar.
True
The large electronegativity difference between ions results in polarity.
What is covalent bonding?
A chemical bond formed by the sharing of electrons between atoms.
Covalent bonds typically form between nonmetals.
Why are covalent bonds directional?
Because shared electrons are localized between two specific atoms.
This contrasts with ionic or metallic bonds, which are non-directional.
List five differences between ionic and covalent bonds.
- Ionic bonds transfer electrons; covalent bonds share electrons.
- Ionic bonds are non-directional; covalent bonds are directional.
- Ionic compounds are usually solids; covalent compounds can be gases, liquids, or solids.
- Covalent compounds are molecules; ionic compounds are lattices.
- Ionic bonds are stronger on average.
List three factors that affect bond strength.
- Bond type (single, double, or triple).
- Bond length.
- Electronegativity difference.
Bond strength increases with shorter bond lengths and higher electronegativity differences.
How does bond length relate to bond strength in covalent bonds?
Shorter bond lengths generally correspond to stronger bonds.
For example, a triple bond is shorter and stronger than a single bond.
How does hybridization affect bond lengths in covalent molecules?
It alters the bond lengths by mixing orbitals.
Single bonds (sp³) are longer and weaker than double bonds (sp²) or triple bonds (sp).
What is the typical bond length of a single covalent bond?
0.15 nm
What is the strongest type of covalent bond?
A triple bond, as it involves three shared electron pairs.
Triple bonds, like in N≡N, are shorter and stronger than single or double bonds.
Why are triple covalent bonds shorter than single bonds?
Triple bonds involve more electron sharing, pulling the nuclei closer together.
Increased electron density between nuclei enhances attraction and shortens the bond.
Why are covalent compounds poor conductors of electricity?
Covalent compounds lack free-moving charged particles.
In contrast, ionic and metallic bonds allow free movement of ions or electrons.
Define:
metallic bonding
Bonding that occurs when metal atoms share a ‘sea’ of free-moving electrons.
Metallic bonds only occur between metal atoms.
What percentage of the periodic table do metals make up?
About 80%.
Metallic characteristics are highest on the left side of the periodic table.
What is the sea of electrons model?
A model describing the ability of electrons to move freely among bonded metal atoms.
This movement is crucial for the properties of metals such as electrical conductivity and thermal energy transfer.
How does the electron sea model explain metallic bonding?
Metal nuclei surrounded by freely moving delocalized electrons.
Why are metallic bonds flexible?
Because the sea of electrons allows metal atoms to move without breaking the bond.
This flexibility makes metals malleable and ductile.
What is the crystalline lattice configuration?
The arrangement of metal atoms in a structured pattern for stability.
This structure provides stability for electron movement.
What does it mean for metals to be malleable?
They can be molded and shaped for various uses.
This property is essential in construction and transportation.
Define:
ductility
The ability of a metal to be stretched into thin wires.
This is important for electrical applications.
Fill in the blank:
The smaller the metal atom, the ______ the metallic bonds will be.
stronger
Smaller atoms have a stronger attraction between protons and electrons.
What happens to metallic characteristics from left to right on the periodic table?
They tend to decrease.
This trend is observed as elements transition to metalloids.
True or False:
Metallic bonds are weaker than ionic bonds.
False
The strength of metallic bonds depends on the number of delocalized electrons and the charge of metal cations.
How does metallic bonding compare to ionic bonding in conductivity?
Metallic bonding allows free electron flow, making metals good conductors in both liquid and solid states, unlike ionic solids.
Ionic compounds conduct electricity only when molten or dissolved in water.
Why are metals malleable while ionic compounds are not?
- Metals: They have a sea of electrons allowing atoms to slide past each other.
- Ionic compounds: They form rigid lattices that break under force.
The delocalized nature of metallic bonds enables flexibility.
What is the relationship between metallic bonding and alloy formation?
Metallic bonding allows the mixture of different metals to form alloys with enhanced properties.
Alloys, such as steel (Fe + C), combine the strength of metals with added flexibility or resistance.
