Bonding Flashcards
Ionic bonding definition
electrostatic force of attraction between oppositely charged ions formed by electron transfer
metals and non metals form which type of ions each?
metals form +ve ions
non metals form -ve ions
What is ionic crystal structure?
Giant lattices of ions
When ions are smaller or have higher charges, what is affected and how?
ionic bonding is affected and becomes stronger
positive ions are larger/smaller than their atoms and the reason why
smaller
one less shell of electrons
ratio of protons to electrons has increased
greater net force on remaining electrons to hold them more closely
negative ions are larger/smaller than their atoms and why (6)
larger
more electrons than in the atom
but same number of protons
so pull of the nucleus is shared over more electrons
the attraction per electron is less
making the ion bigger
What do N3- , O2-, F-, Na+, Mg2+ and Al3+ have in common? Why do their ionic radii decrease?
the same electronic structures (neon)
increasing no of protons from N to F and Na to Al but same number of electrons
Nuclear attraction per electron increases and ions get smaller
Covalent bond definition
A shared pair of electrons between 2 atoms
define dative covalent bond and what is an alternative name?
one forming when a shared pair of electrons in the covalent bond icome from only one of the bonding atoms, aka a coordinate bond
Give 3 examples of molecules with a dative bond and state which bond is dative in that molecule.
NH4+ (N-> H)
H3O+ (O-> H)
NH3BF3 (N-> B)
Metallic bonding definition
Electrostatic force of attraction between the positive metal ions and the delocalised electrons
3 factors affecting strength of metallic bonding
- number of protons/strength of nuclear attraction - the more protons the stronger the bond
- number of delocalised e- per atom - the more delocalised e- the stronger the bond
- size of the ion - the smaller the ion, the stronger the bond
Why does Mg have stronger metallic bonding than Na and a higher boiling point? (5)
In Mg there are more electrons in the outer shell of each atom released to the sea of electrons
The Mg ion is also smaller
It also has one more proton
There is a stronger electrostatic attraction between the positive metal ions and the delocalised electrons
More energy is required to break bonds
4 different molecular structures, their bonding and examples for each
Giant ionic lattice
ionic
NaCl
MgO
Simple molecular (with intermolecular forces)
Covalent
Iodine
Ice
CO2
Water
Methane
Macromolecular
Covalent
Diamond
Graphite
Silicon dioxide
Silicon
Giant metallic lattice
Metallic
Mg
(all metals)
When to use the words molecules/intermolecular forces
When dealing with simple molecular substances
Ionic properties
Melting/boiling points
Solubility in water
Conductivity when solid
Conductivity when molten
General description
High because of giant lattice of ions with strong electrostatic forces between oppositely charged ions
Generally good
Poor, ions can’t move when fixed in lattice
Good, ions can move
Crystalline solids
Simple molecular properties
Melting/boiling points
Solubility in water
Conductivity when solid
Conductivity when molten
General description
Low, because of weak intermolecular forces between molecules
Poor
Poor, no ions to conduct and electrons are localised (fixed in place)
Poor, no ions
Mostly gases and liquids
Macromolecular properties
Melting/boiling points
Solubility in water
Conductivity when solid
Conductivity when molten
General description
high, because of many strong covalent bonds in the structure which take a lot of energy to break
Insoluble
Diamond and sand poor as electrons are localised
Graphite is good as free electrons move between layers
Poor
Solids
Metallic properties
Melting/boiling points
Solubility in water
Conductivity when solid
Conductivity when molten
General description
High due to strong electrostatic forces between cations and delocalised electron sea
Insoluble
Good, delocalised e- move through structure
Good - “ “
Shiny metal, malleable due to planes of identical ions sliding over each other as attractive forces in the structure are the same whichever ions are adjacent to each other