ionic bonding occurs between metals and non-metals
in ionic bonding, electrons are transferred from metal atoms to non-metal atoms to achieve full outer shells, forming positive and negative ions
in ionic compounds, oppositely charged ions are attracted to each other by electrostatic forces, forming a giant ionic lattice, this is a 3D structure
the formula of a sulfate ion is SO4(2-)
the formula of a hydroxide ion is OH(-)
the formula of a nitrate ion is NO3(-)
the formula of a carbonate ion is CO3(2-)
the formula of an ammonium ion is NH4(+)
covalent bonding occurs between non-metals and other non-metals
in covalent bonding, electrons are shared between the two outer shells to achieve full outer shells
multiple electron pairs can be shared to produce multiple covalent bonds
coordinate bonding is a form of covalent bonding where both electrons in the shared pair are supplied from a single atom
coordinate bonds react in the exact same way as covalent bonds
in a diagram, covalent bonds are shown with a line, coordinate bonds are shown with an arrow
metallic bonding occurs between metals and other metals
in metallic bonding, the greater the charge of the positive ion, the stronger the electrostatic forces as more electrons are released into the sea
in metallic bonding, a sea of delocalised electrons surrounds a lattice of positive ions, held together by strong electrostatic forces of attraction between negative electrons and positive ions
the larger the positive ion, the weaker the electrostatic forces as the nucleus is further from the delocalised electrons
electronegativity is the ability of an atom to attract the electron density in a bond, the bonding pair of electrons, towards itself
electronegativity increases going up a group because atoms get smaller, and there is less shielding
electronegativity increases going across a period because nuclear charge increases, atoms gets smaller, but number of energy levels is constant
the most electronegative atom is F, then O, N, Cl
the negative charge in a covalent bond is not distributed evenly, unless both atoms are of the same element, as different atoms have different electronegativities
covalent bonds are polar, and increase in polarity as the difference in electrnoegativity of the atoms increases
there are 3 types of intermolecular forces:
van der Waals
dipole-dipole
hydrogen bonding
van der Waals forces act between all atoms and molecules
van der Waals forces are the weakest type of intermolecular force
as Mr increases, strength of van der Waals forces increases, as there are more electrons
compounds with unbranched molecules have stronger van der Waals than compounds with branched molecules because the straight molecules can pack closer together
dipole-dipole forces act between molecules with a polar bond
in a polar bond, the delta-positive and delta-negative regions attract each other, holding the molecules together
hydrogen bonds form between hydrogen atoms and either fluorine, oxygen, or nitrogen atoms
hydrogen bonds are the strongest type of intermolecular force
to form a hydrogen bond, the lone pair on the fluorine/oxygen/nitrogen of one molecule is attracted to the hydrogen of another molecule
to draw hydrogen bonds:
show the bond as a dotted line
it must be 180 degrees
label the delta-positive and delta-negative regions
molecules form different shapes depending on the number of bonding pairs and lone pairs they have, and the shapes have specific angles