1.3 Bonding Flashcards
(21 cards)
What is ionic bonding?
Strong electrostatic forces of attraction between oppositely charged ions held in a lattice
How high are ionically bonded substances bp and mp?
High, takes a lot of energy to break the strong electrostatic forces pf attraction between oppositely charged ions
Do ionic compounds conduct electricity?
Yes, when in solution as the ions are free to move and carry a charge
What is simple molecular covalent bonding?
Strong covalent bonds between atoms, weak van der Waals forces of attraction between molecules
Do simple molecular substances have a high or low bp/mp?
Low - weak van der Waals forces of attraction between molecules that don’t take much energy to overcome
Describe Macromolecular covalent bonding
Lattice of many atoms held together by strong covalent bonds
Do substances with macromolecular covalent bonds have high or low bp/mp?
High - It takes a lot of energy to overcome many strong covalent bonds
Describe the structure of diamonds?
- A 3d tetrahedral structure of C atoms
- Each C atom bonded to four others
Do metallic compounds have high/low bp/mp?
High as strong forces of attraction between positive metal ions and negatively charged sea of delocalised electrons
How does the strength of metallic bonds change across the periodic table? Why?
- Increases - Higher Mp + Bp
- Higher charge on metal ions
- More delocalised electrons per ion
- Stronger forces of attraction between them
What is electronegativity?
The ability of an atom to attract the pair of electrons (the electron density) in a covalent bond
What are the 3 things that affect electronegativity?
- Nuclear Charge
- Atomic Radius
- Electron Shielding
How do you get a nonpolar bond?
Both bonding elements have the same electronegativities
What is the strongest type of Inter-Molecular force?
H-Bonds
What is the weakest type of Inter-Molecular force?
Van der Waals
Describe VDW forces of attraction
- Temporary dipoles are created by the random movement of electrons.
- Induces dipole in neighbouring molecule
- Temporary induced dipole-dipole attraction aka van der waals forces of attraction
What is permanant dipole-dipole?
- Some molecules with polar bonds have permanent dipoles
Why is ice less dense than liquid water?
- In liquid water, H-bonds constantly break and reform as molecules move about
- In ice, the H-Bonds hold the molecules in fixed positions; this makes them slightly further apart than in water
When is a dative/covalent bond formed?
Formed when an electron deficient atom accepts a lone pair of electrons from an atom with a lone pair of electrons
What does the shape of a molecule depend upon?
- The number of electrons in the valence shell of the central atom
- Numbers of these electrons which are in bonded or lone pairs
What does the Electron Pair Repulsion Theory state?
- That electron pairs will take up positions as far away from each other as possible
- To minimise the repulsive forces between them
