3. Bonding Flashcards
(22 cards)
What is an ionic bond?
Occurs in solid materials in a lattice of oppositely charged ions
Ionic bonds are characterized by the strong electrostatic attraction between cations and anions.
What is the reaction representing the formation of sodium chloride?
2Na (s) + Cl2 (g) → 2 NaCl (s)
This reaction shows the combination of sodium and chlorine to form sodium chloride.
What is the relationship between ionic bond strength and ion size?
Smaller the ion size, larger the charge on ions
Stronger ionic bonding requires more energy to overcome electrostatic interactions.
What happens to energy requirements as you move down a group in the periodic table?
Less energy is required to overcome bonds
This trend is due to increasing ionic radii as more electron shells are added.
What evidence supports the existence of ions?
Ionic compounds can conduct electricity and undergo electrolysis in molten or aqueous state
Positive ions (cations) migrate towards the cathode and anions migrate towards the anode.
What is the trend in ionic radii as you go down a group?
Ionic radii increase due to additional electron shells
Increased proton number attracts electrons more strongly, affecting ionic radius.
What are isoelectronic species?
Same number of electrons, same electronic configuration, same chemical properties
Isoelectronic species can differ in size and charge.
What is polarization in the context of ionic bonds?
Cation attracts electrons of the anion, distorting electron density
This distortion leads to the anion being polarized.
Fill in the blank: The strength of polarization depends on the size of the _______ and the charge of the cation.
cation
Larger cations can have a stronger polarizing effect.
True or False: Anions lose electrons at the anode during electrolysis.
True
Anions migrate towards the anode where they lose electrons.
What is polarisation in ionic compounds?
The distortion of electron density of a negative ion
Polarisation occurs when a positive ion affects the electron cloud of a negative ion, leading to distortion.
Define power in the context of ionic compounds.
The ability of a positive ion to distort the electron density of a negative ion
This power is a measure of how much the positive ion can influence the electron cloud of a nearby negative ion.
List the physical properties of ionic compounds.
- High melting temperature
- Brittle
- Conduct in molten state
- Solubility in water
These properties arise due to the strong ionic bonds and the arrangement of ions in the lattice structure.
Why do ionic compounds have high melting temperatures?
A large amount of energy is required to overcome forces of attraction and for ions to break free from the lattice
The strong electrostatic forces between ions contribute to the high melting points.
Explain why ionic compounds are brittle.
Layers of ions slide, causing ions of the same charge to repel each other
When stress is applied, the shifting of layers leads to repulsion and fracture.
When do ionic compounds conduct electricity?
Only when molten, as electrons are free to move
In solid form, ions are locked in place within the lattice structure and cannot conduct electricity.
What causes the solubility of ionic compounds in water?
Ions are attracted to water molecules because of its polarity (hydration)
Water’s polar nature enables it to surround and separate ions in an ionic compound.
What is a covalent bond?
A strong electrostatic attraction between two nuclei and the shared pair of electrons between them
Covalent bonds involve the sharing of electron pairs between atoms, leading to molecular formation.
What is a sigma bond?
A single covalent bond formed by end-to-end overlap of two electron orbitals between bonding atoms
Sigma bonds are the strongest type of covalent bond due to the direct overlap of orbitals.
What is a pi bond?
An additional bond formed by the sidewise overlap of two p orbitals above and below the bonding axis
Pi bonds are found in double and triple bonds alongside sigma bonds.
How many types of covalent bonds exist based on the number of shared electron pairs?
- Single covalent bond
- Double covalent bond
- Triple covalent bond
Each type of bond increases the number of shared electron pairs, affecting bond strength and length.
What is the relationship between single, double, and triple covalent bonds in terms of shared electron pairs?
Single bond: 1 pair, Double bond: 2 pairs, Triple bond: 3 pairs
The number of shared pairs directly corresponds to the bond type and its respective strength.
