1.3 Bonding Flashcards
What type of bonding is involved in NaCl?
Ionic bonding
Define dative bonding.
A covalent bond in which both electrons are donated by the same atom
Give an example of a permanent dipole-dipole bond.
H2O, HCl, NH3
What is the strongest type of bond?
Covalent
Describe the solubility of ionic compounds.
Ionic compounds tend to dissolve in water. Water molecules are polar and pull the ions away from the ionic lattice, causing it to dissolve.
Suggest why simple covalent compounds have low melting points.
They have weak intermolecular forces which are easily broken
Give another name for dative bonding.
Co-ordinate bonding
Describe valence-shell electron-pair repulsion theory.
As lone pairs of electrons have greater angles between them than in bonding pairs, the shape of a molecule can be determined by the number and type of charge clouds on the valence shell.
What is electronegativity?
Electronegativity is the ability or tendency of an element to attract the electron density in a covalent bond towards itself.
Name the 3 main types of intermolecular forces. State which are the weakest and strongest.
- Induced dipole-dipole (Van der Waals) —Weakest
- Permanent dipole-dipole
- Hydrogen bonding — Strongest
What is the bond angle between electron pairs in a trigonal pyramidal molecule?
107
Name the type of structure a molecule will have if it has 6 bonding pairs on the central atom.
Octahedral
Explain why ionic compounds conduct electricity when molten but not when solid.
The ions in the liquid are free to move and they carry a charge. In a solid they’re fixed in position by strong ionic bonds
Explain why graphite is a conductor.
Each carbon atom only makes 3 covalent bonds, not 4, so for every atom there is a delocalised electron which can carry charge
How many bonding pairs of electrons are on the central atom of a tetrahedral molcule?
4
Explain why ice is less dense than water.
Ice has more hydrogen bonds than water, and the hydrogen bonds are quite long meaning the H2O molecules in ice are further away from each other than they are in water. This makes ice less dense than water.
Give an example of a bent/non linear molecule and state its bonding angle.
Water (H2O)
104.5
How many electron pairs and lone pairs does a trigonal pyramidal molecule have?
3 electron pairs and 1 lone pair
How is a dipole formed?
A dipole is caused by a shift in electron density in the bond due to differences in electronegativity. There will be a difference in charge between the two atoms (one is slightly positive and one is slightly negative).
What is the most electronegative element?
Fluorine
Hydrogen bonding will only occur when hydrogen is covalently bonded to which three elements?
Fluorine, nitrogen and oxygen
Which factors affect the melting point of metals?
- Number of delocalised electrons
- Size of the metal ion
Why are metals good thermal conductors?
The delocalised electrons are free to move and can pass kinetic energy to each other.
What name is given to a molecule with 5 electrons pairs? Give an example.
Trigonal bipyramidal e.g PCl5
What is the bonding angle between a tetrahedral molecule e.g NH4+?
109.5
