3P-Bonding Flashcards
What’s ionic bonding
electrostatic attraction between oppositely charged ions in a lattice.
What’s a single covalent bond and multiple bonds eg double bonds
Contains one shared pair of electrons
Or multiple pairs of shared electrons eg 2 pairs for double bonds
What are coordinate or dative covalent bonds and how are they represented
Contain a shared pair of electrons with both electrons supplied by one atom
Drawn with an arrow
What’s metallic bonding
involves attraction between delocalised electrons and positive ions arranged in a lattice
What are the crystal structures and examples of them
Ionic eg sodium chloride
Metallic eg magnesium
Macromolecular (giant covalent) eg graphite, diamond
Molecular eg ice, iodine
What’s the melting point, solubility in water and conductivity of ionically bonded substances
High mps and bps- giant lattice structure, lots of energy needed to overcome
Solubility in water- good
Conductive- only when aqueous or molten, ions are free to move carrying the charge
What’s the melting point solubility in water and conductivity of covalently bonded structures
Low mps and bps- weak intermolecular forces, easy to overcome
Solubility in water- poor/insoluble
Not conductive- molecules aren’t ions
Melting points solubility in water and conductivity of metallically bonded structures
High mps and bps- strong attraction between metal ions and delocalised sea of electrons in a giant structure
Solubility in water- insoluble
Conductive- delocalised electrons free to move through structure carrying charge
Other properties of metallically bonded substances
Heat conductor- ions packed closely, high thermal conductivity
Malleable and ductile- can be moulded into shape, drawn into wires
Factors effecting strength of ionic covalent or metallic bonds
Atomic radius, larger radius less attraction to nucleus
Charge, larger, more electrons shared or transferred so greater attraction
How much energy do different states have
Solid- little energy, particles vibrate around a fixed point
Liquid- moderate energy, particles still touching but can flow
Gas- lots of energy, particles bounce off eachother
What’s the name and bonding angle for a molecule with 2 bonding pairs of electrons
Linear
180°
What’s the name and bonding angle of a molecule with 3 bonding pairs of electrons
Trigonal planar
120°
What’s the name and angle of a molecule with 4 pairs of bonding electrons
Tetrahedral
109.5°
What’s the name and angle of a molecule with 5 pairs of bonding electrons
Trigonal bipyrimidal
120° (between back and forward atom)
90° (between atoms on same plane)
What’s the name and angle of a molecule with 6 bonding pairs of electrons
Octahedral
90°
Why do pairs of electrons organise themselves as far as possible from eachother
Due to repulsion
In order of most repulsive to least repulsive list whether lone pair or bond pair electrons are most repulsive and why
Lone pair-Lone pair (pulled closer to nucleus, more repulsive)
Lone pair-Bond pair
Bond pair-Bond pair
How much does a bond angle reduce with one lone pair
2.5°
What’s the name and bond angle of a molecule with 3 bonding pairs and 1 lone pair of electrons
Trigonal pyramidal
107°
What’s the name and bonding angle of a molecule with 2 bonding pairs and 2 lone pairs of electrons
Bent
104.5°
What are the changes of state
Solid to liquid, melting
Liquid to solid, freezing
Liquid to gas, boiling
Gas to liquid, condensing
Solid to gas, sublimation
Gas to solid, deposition
What’s electronegativity
The power of an atom to attract the electrons in a covalent bond
How to know if a molecule is polar
The polar bonds will act unsymetrically and elements will have different electronegativities
Even if a molecule has polar bonds the molecule may not be polar why
The polar bonds may act symmetrically with equal electronegativity
What does a polar molecule possess
A permanent dipole
What shows a polar bond
An arrow with a line through it
What’s the trend in electronegativity across a period
Increases, increase in number of protons, more attraction, similar shielding
What’s the trend of electronegativity down a group
Decreases, larger atomic radius, shielding, less attraction for shared pair of electrons to nucleus
What are the S+ and S- regions of a polar molecule
S+, atom has less attraction, electron deficient
S-, atom has a stronger attraction, electron sufficient
What are induced dipole-dipole forces and how are they formed (van der waals, london dispersion)
Occur between all molecules
Weakest intermolecular force
Between noble gas atoms
Electrons move randomly, electron density changes at parts of molecule (s+ and s- regions), formation of a temporary dipole, form induced dipoles in neighbouring molecules
What are permanent dipole-dipole forces
Occur between polar molecules, add to induced dipoles (van der waals) present
What are hydrogen bonds
Occurs in molecules where a hydrogen atom is attracted to the lone pair of electrons on either nitrogen, oxygen or fluorine (NOF) of another molecule
Strongest intermolecular forces
What do you need to include when drawing hydrogen bonds
Include the S+ and S- sides
Include dashes to show the bonds
Include the lone pair of electrons
What happens to melting and boiling points when intermolecular forces become stronger
Increase
How do hydrogen bonds cause anomalously high boiling points
Hydrogen bonds are in addition to induced dipoles and more forces this need more energy to overcome
Why is the density of ice low
Hydrogen bonds cause water molecules to be far apart, gaps in lattice
How does a higher Mr effect the strength of intermolecular forces
Higher Mr, more electrons, stronger van der waals forces between molecules
How do isomers effect strength of intermolecular forces
Isomers which allow molecules to be packed closely have stronger induced dipoles
What’s the name and the bonding angle of a molecule with 4 bonding pairs and 2 lone pairs
Square planar
90°
