Bonding Unit Flashcards
What is a non-polar bond?
The electronegativity of the atoms is the same, and therefore the electron pair is shared equally, a bond of two atoms of the same element.
What is a polar bond?
The electronegativities of the atoms are different, and the electron pair is not shared equally, a bond of two atoms of different elements.
How is the degree of polarity determined?
By the difference in electronegativity between the atoms and the symmetry.
What is molecular polarity?
The uneven distribution of molecular charge, the existence of both a positive and a negative end of a molecule.
What happens if a molecule contains polar bonds, but is symmetrical?
It is non-polar.
Why do multiple covalent bonds occur?
Because sometimes to fill up a valence shell of an atom, more than one pair of electrons are needed.
What do compounds containing polyatomic ions have and why?
They have both ionic and covalent bonding because the polyatomic ions are held together by polar covalent bonds.
What are coordinate covalent bonds?
One atom supplies both electrons for the bond because an ion is attracted to the unshared pair of electrons in a molecule.
What are network solids?
Solids in which all of the atoms are covalently bonded to each other, lattice structure.
What are the types of network solids?
Diamond - made of carbon
graphite - carbon
silicon dioxide (SiO2)
silicon carbide (SiC)
What is metallic bonding?
- atoms in metal are held together by these
- the valence electron of a metal atom are held loosely to the atom
- these electrons are like positive ions
- all the positive ions share the electrons, creating the electron sea
- the electrons can move throughout
What does this explain?
The malleability and conductivity of metal (because the electrons can move, electricity is conducted).
What holds a molecular covalent substance together in the solid or liquid phase?
Attractive/intermolecular forces.
What are the intermolecular forces?
dipole-dipole attraction
hydrogen bonding
London dispersion act
What is dipole-dipole attraction?
In a polar substance, the positive end of each dipole is attached to the negative end of the next.
What is hydrogen bonding?
It is the strongest form of intermolecular attraction, hydrogen bonds form between molecules in which hydrogen is bonded to small atoms having high electronegativity.
What is hydrogen bonding responsible for?
unusual properties of water
- water has a relatively high boiling point and low vapor pressure for a small molecule
- water expands when it freezes
- surface tension
What happens when water freezes?
The hydrogen bonds hold the molecules in a rigid structure with spaces in between.
Why does surface tension occur?
The hydrogen bonding between water molecules in the liquid phase are shared with all neighboring molecules, those on the surface have no neighboring molecules above and therefore, have stronger hydrogen bonds with their nearest neighbors and below the surface.