Unit 1 Flashcards
Properties of a giant ionic structure
High melting point
Brittle
Conductivity
What is a covalent bond
Two non metals sharing a pair of electrons
What is the attraction between electrons and the nucleus called
Electrostatic attraction
What is average bond enthalpy
Degree of strength a covalent bond has
What is a dative bond
A covalent bond where both electrons come from the same atom
How do you demonstrate a dative bond
Arrow points from the atom donating the lone pair to the atom accepting it
What is it called when an atom doesn’t have all the electrons it could
Electron deficient
What is the basic theory of shapes of molecules
Molecules take up the shape that minimises repulsion between electron pairs within the molecule
What do dotted lines and wedges show
Dotted- bond going away
Wedge- bond coming towards
What is Electronegativity
the ability of an atom in a covalent bond to attract the bonded pair electrons
As you go down a group, what happens to Electronegativity
Decreases
Due to increased shielding
What happens to Electronegativity across a period
Increases due to the increasing nuclear charge decreasing the size of the atoms
what is a pure covalent bond
where the electrons are shared evenly between the 2 atoms
what is a polar bond
one end is slightly positive and the other slightly negative
what is a permanent dipole
the two opposite charges within the molecule are poles
how to calculate charge density
charge of the ion/ionic radius
how does polarising ability change
increases as the positive ion gets smaller and the number of charges gets larger
what are intermolecular attractions
attractions between one molecule and a neighbouring molecule
what is a permanent dipole/ permanent dipole attraction
occurs between polar molecules which have a permanent dipole
what is hydrogen bonding
dipole-dipole attraction
hydrogen bond must be attached to N, O, F electrons on the electronegative atom
what are London forces
temporary dipole- induces a dipole attraction- but is constantly changing as electrons move around
what happens to London forces as molecules get bigger
number of electrons increases, making the molecule more polarisable, producing greater induced dipole attractions
if a gas, liquid has a low melting point what does this tell you
covalently bound molecules
what does it tell you if something is soluble
hydrogen bonding
what does a high melting point solid suggest
giant ionic/metallic/covalent
