Structure and Bonding Flashcards
What is ionic bonding?
Transfer of electrons from metallic and non-metallic
What is a cation and anion
Cation = lose e-, positively charged ion
Anion = gain e-, negatively charged ion
What type of force does an ionic bond have
Electrostatic attractions between oppositely charged ions forming ionic compounds
What do the strong electrostatic forces between ions mean
Lots of energy
High melting and boiling points
Electrical conductivity of ionic compounds
Molten or dissolved
Ions free to move
Solubility ionic bonding
Dissolve in water, water molecules are polar so pull ions away from lattice so it dissolves
Giant ionic lattices structure
Arranged in regular repeating pattern so positive charged cancel out negative charges
Overall electrically neutral
Covalent bond electrons
Sharing between a pair of electrons between two non-metals
Forces in covalent bonding
Electrostatic attraction between nuclei of two atoms and bonding electrons of outer shells
Type of bonds in covalent bonding
Single - both molecules overlap in dot and cross diagram
Double = O=C=O
Triple = N=-N
Forces in simple covalent bonding of molecule
Van der waals
Strong covalent bonds and intermolecular forces
Giant covalent Graphite
Weak bonds easily broken so slide over each other, delocalised electrons for electrical conductivity, low density because layers are far apart, soluble
Giant covalent diamond
High melting point, hard, vibrations travel easily so good thermal conductor, cant conduct electricity, wont dissolve in solvent
Why does HCl conduct electricity
HCl is an acid so it dissociates into H+ and Cl- which are ions, so can carry charge
What is a dipole
Unequal distribution of electronegativity between two atoms
(one partially positive other partially negative)
What’s a dipole moment
Looking at whole molecule not just two atoms within molecule
What if a molecule is symmetrical
Dipoles cancel out and there is no overall dipole moment
How to draw dipole
arrow with line in it
-/->
What is a co-ordinate bond
Both electrons shared come from same atom
Example of dative bond
NH4
What’s a lone pair
unshared electron pair
Why do lone pairs repulse the most
more concentrated electron cloud than other bonding pairs of electrons
Cloud charges are wider and closer to central atom’s nucleus
Order of repulsion
lone pair to lone pair > lone pair to bind pair > bond pair to bond pair
What molecules are van der waal forces in
all molecules
How do van der waals forces act
Electron charge cloud in non-polar molecules constantly moving. Electron cloud can be more one side of the atom than the other, causing a temporary dipole which induces neighbouring molecules. This causes one atom to be partially positive and the neighbouring molecules atom partially negative, attracting them. Clouds constantly moving so only temporary dipole.
