Ionic bonding Flashcards
1
Q
What is lattice enthalpy?
A
Measure of the strength of the forces between ions in an ionic solid
2
Q
What determines lattice enthalpy?
A
Charge density of the ions
3
Q
What 2 factors determine charge density?
A
- Charge: greater charge=greater charge density
- Size: the bigger the ion, the smaller the charge density.
Charge is the most important factor
4
Q
Relationship between length of a bond and its strength
A
The longer the bond, the weaker it is.
5
Q
Factors affecting the strength of metallic bonds
A
- Charge density of ions
- No. of electrons in sea of delocalised electrons
6
Q
Electronegativity
A
The tendency for an atom to attract an electron
7
Q
What scale is used to measure electronegativity?
A
Pauling scale
8
Q
Criteria for a non-polar covalent bond
A
- Atoms have the same or very similar electronegativity (0-0.5 difference)
- Neither atom is pulling the bonding pair towards itself
- Shared electron pair located in exact middle
- Charge distributed equally around molecule
9
Q
Criteria for a polar covalent compound
A
- Atoms have somewhat different electronegativity(0.6 - 1.7 difference)
- Atom with greater electronegativity pulls electron pair towards isteld
- There are more electrons near the more electronegative atom, creating a slight negative charge there
10
Q
Criteria for ionic bonds
A
- Atoms have significantly different electronegativity (difference > 1.7)
- Atom with greater electronegativity pulls electron towards itself, completely removing it
- Produces positive and negative ion with electrostatic force between them
- But the positive ion still has an electronegativity, so it pulls the electron slightly.
11
Q
Criteria for metallic bonds
A
- Low average electronegativity (< 2) and small electronegative difference (< 1)
- Metals have lower electronegativities than non-metals
