Bonding-physical chemistry Flashcards
What is ionic bonding?
Ionic bonding is the electrostatic attraction between oppositely charged ions in a giant lattice.
It occurs between metals (which lose electrons to form cations) and non-metals (which gain electrons to form anions).
What are the formulas of important compound ions?
Ion Name Formula Charge
Sulfate SO₄²⁻ -2
Hydroxide OH⁻ -1
Nitrate NO₃⁻ -1
Carbonate CO₃²⁻ -2
Ammonium NH₄⁺ +1
How can you predict the charge of a simple ion?
Group 1 metals → +1 (e.g., Na⁺, K⁺)
Group 2 metals → +2 (e.g., Mg²⁺, Ca²⁺)
Group 6 non-metals → -2 (e.g., O²⁻, S²⁻)
Group 7 non-metals → -1 (e.g., Cl⁻, Br⁻)
How do you write the formula of an ionic compound?
Identify the ions and their charges.
Balance the charges to ensure the overall compound is neutral.
What is a covalent bond?
A covalent bond is formed when two atoms share a pair of electrons.
The shared electrons help both atoms achieve a stable electron configuration (full outer shell).
Covalent bonds occur between non-metal atoms.
What is the difference between single and multiple covalent bonds?
Single bond: One shared pair of electrons (e.g., H–H in H₂)
Double bond: Two shared pairs (e.g., O=O in O₂)
Triple bond: Three shared pairs (e.g., N≡N in N₂)
What is a co-ordinate (dative covalent) bond?
A co-ordinate bond is a covalent bond where both electrons in the shared pair come from one atom.
Represented using an arrow (→) pointing from the donor atom to the acceptor atom.
How do we represent covalent and dative covalent bonds?
Covalent bonds: A simple line (-) between atoms.
Example: H–Cl (Hydrogen chloride)
Dative covalent bonds: An arrow (→) from donor to acceptor.
Example: NH₄⁺ (Ammonium ion): N → H
What is metallic bonding?
Metallic bonding is the electrostatic attraction between delocalised electrons and positive metal ions arranged in a giant lattice.
The delocalised electrons move freely, allowing metals to conduct electricity and heat.
How are metal atoms arranged in metallic bonding?
Regular lattice structure of positive metal ions.
Sea of delocalised electrons moving freely throughout the structure.
Strong electrostatic forces between the electrons and metal ions hold the structure together
What are the key properties of metals, and how does metallic bonding explain them?
A:
Property Explanation (Due to Metallic Bonding)
.High melting & boiling point-Strong electrostatic attraction between positive metal ions and delocalised electrons requires a lot of energy to break.
Good electrical conductivity-Delocalised electrons can move freely, carrying charge.
Malleable & Ductile-Layers of metal ions can slide over each other while maintaining bonding.
Good thermal conductivity-Delocalised electrons transfer thermal energy efficiently.
What factors affect the strength of metallic bonding?
Number of delocalised electrons → More electrons = stronger bonding.
Charge of the metal ion → Higher charge = stronger attraction.
Size of the metal ion → Smaller ions = stronger attraction.
Example:
Magnesium (Mg²⁺) has stronger metallic bonding than Sodium (Na⁺) because Mg²⁺ has more delocalised electrons and a higher charge.
What are the four types of crystal structures?
Ionic → Giant lattice of oppositely charged ions (e.g., NaCl).
Metallic → Lattice of metal cations in a sea of delocalised electrons (e.g., Mg).
Macromolecular (Giant Covalent) → Large structures with strong covalent bonds (e.g., Diamond, Graphite).
Molecular → Small molecules held by intermolecular forces (e.g., I₂, Ice).
How do bonding and structure affect melting points and conductivity?
High melting points → Found in giant covalent, metallic, and ionic structures due to strong bonds.
Conductivity:
Metals → Conduct as delocalised electrons move freely.
Ionic compounds → Conduct when molten or in solution (ions move).
Giant covalent (Graphite) → Conducts due to delocalised electrons.
Molecular structures (Ice, I₂) → Do not conduct (no free electrons/ions).
What energy changes occur when substances change state?
Melting/Boiling: Energy is needed to break bonds or intermolecular forces.
Freezing/Condensation: Energy is released as bonds form.
Strong bonds (ionic/metallic/giant covalent) → More energy required to melt/boil.
Weak intermolecular forces (molecular structures) → Less energy required to melt/boil.
How do you represent different crystal structures in diagrams?
Ionic lattice → Alternating positive and negative ions.
Metallic lattice → Positive metal ions in a sea of delocalised electrons.
Giant covalent (Diamond/Graphite) → Networks of atoms bonded covalently.
Molecular (Ice/Iodine) → Small molecules held by intermolecular forces.
What is the structure and properties of diamond?
Structure: Giant covalent lattice where each carbon atom is covalently bonded to 4 others in a tetrahedral arrangement.
Properties:
Extremely hard (strong bonds in all directions)
Very high melting point (strong covalent bonds require a lot of energy to break)
Does not conduct electricity (no delocalised electrons)
What is the structure and properties of graphite?
Structure: Hexagonal layers of carbon atoms, each bonded to 3 others. Delocalised electrons move between layers.
Properties:
Soft & slippery (layers held by weak van der Waals forces, so they slide easily)
Conducts electricity (delocalised electrons move freely)
Very high melting point (strong covalent bonds within layers)
What is the structure and properties of ice?
Structure: Water molecules held in a hexagonal arrangement by hydrogen bonds.
Properties:
Lower density than water (hydrogen bonds hold molecules further apart)
Low melting point (intermolecular forces are weak compared to covalent/ionic bonds)
Does not conduct electricity (no free electrons or ions)
What is the structure and properties of iodine?
Structure: Simple molecular structure, with I₂ molecules held by weak van der Waals forces.
Properties:
Soft and brittle (weak intermolecular forces)
Low melting & boiling point (easy to overcome van der Waals forces)
Does not conduct electricity (no delocalised electrons)
What is the structure and properties of magnesium?
Structure: Positive Mg²⁺ ions in a giant lattice, surrounded by a sea of delocalised electrons.
Properties:
Conducts electricity (delocalised electrons move freely)
Malleable & ductile (layers can slide while maintaining bonding)
High melting point (strong metallic bonds require a lot of energy to break)
What is the structure and properties of sodium chloride?
Structure: Giant ionic lattice of alternating Na⁺ and Cl⁻ ions, held by strong electrostatic attraction.
Properties
High melting point (strong ionic bonds require a lot of energy to break)
Conducts electricity when molten or dissolved (ions are free to move)
Brittle (shifting layers can cause like charges to repel, breaking the lattice)
What is electronegativity?
Electronegativity is the power of an atom to attract the pair of electrons in a covalent bond.
✔ Measured using the Pauling scale (fluorine is the most electronegative element)
What factors influence an atom’s electronegativity?
Atomic charge → More protons = higher electronegativity.
✔ Atomic radius → Smaller atoms = stronger attraction for bonding electrons.
✔ Shielding effect → More electron shells reduce attraction for bonding electrons.
