Covalent Bonding Flashcards
What is covalent bonding?
2 non-metals sharing a pair of electrons to form structures isoelectronic to noble gases.
What does ‘isoelectronic’ mean?
Isoelectronic refers to two atoms, ions, or molecules that have the same electronic structure and the same number of outer shell electrons.
Why do covalent molecules stay together?
The attraction between the positive nuclei and the shared electrons is greater than the repulsion between the nuclei themselves. This is called electrostatic attraction.
What is average bond enthalpy?
Degree of strength a covalent bond has. The higher this value, the stronger the bond.
What is dative (co-ordinate) bonding?
Covalent bond in which both electrons come from the same atom.
What is an example of dative bonding?
Ammonia (NH3) gaining a hydrogen atom with no electrons. The hydrogen atom bonds with the unshared pair of electrons in ammonia to form NH4+.
How is a dative bond represented in a diagram?
With an arrow pointing from the donor of shared electrons to the atom receiving them.
Why is NH4+ positive after it gains a hydrogen ion?
The hydrogen ion has no electrons and is effectively a single proton.
What happens to the electron hydrogen loses?
It is left behind on another atom, e.g. chlorine may keep hydrogen’s electron behind
Why is boron trifluoride (BF3) described as electron deficient?
Boron only has 3 pairs whereas there would be room for 4 pairs (there are 6 electrons in boron’s outer shell)
Why are covalent compounds poor conductors of electricity?
No ions and no free electrons
Why do simple covalent compounds have low MPs?
Weak intermolecular forces and so relatively little energy is required to overcome these forces.
