Electrons and bonding (definitions) Flashcards
Sub-shell def
A sub-division of an energy level. Sub-shells may be s, p, d or f sub-shells.
orbital def
A region of a sub-shell that contains a maximum of 2 electrons with opposite spin
ionic bond def
the electrostatic attraction between positive and negative ions
ionic compound
compound made from oppositely charged ions
What makes ionic bonds stronger, what does this result in
bigger charges higher melting points
when do ionic compounds conduct electricity and why
when molten or dissolved, not solid ions free to move and carry charge
whats the solubility of ionic compounds
soluble in polar solvents e.g. water.
whats the metling/boiling points of ionic compounds (high or low)
very high. Giant ionic lattices held by strong electrostatic forces. Loads of energy needed to overcome forces.
covalent bond def
strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
dative covalent bond (coordinate bond) def
a covalent bond formed when 1 atom provides both of the shared electrons.
how are dative covalent bonds represented
with arrow coming from where pair of electrons is coming from
electron shell def
a region of an atom with a fixed energy that contains electrons orbiting the nucleus
electron shell repulsion theory
in a molecule lone pair/lone pair bond angles are biggest lone pair/bonding pair angles are second biggest bonding pair/bonding pair angles are smallest
electronegativity def
ability of an atom to attract the bonding electrons in a covalent bond
permanent dipole - dipole interactions
intermolecular forces that exist because the difference in electronegativities in a polar bond causes weak electrostatic forces of attraction between molecules
what E.N difference is there for non-polar covalent bonds
<0.4
what E.N difference is there for ionic but still mainly covalent
0.4 - 2.0
what E.N difference is there for mainly ionic
2>
Name the 3 tyoes of intermolecular force
induced, permanent hydrogen
induced dipole - dipole (London forces) def
type of intermolecular force caused by temporary dipoles, which causes all atoms and molecules to be attracted to eachother.
what increases strength of london forces
larger molecules (larger electron clouds) larger S/A
what elements can hydrogen occur with
fluorine, nitrogen, oxygen
why is ice less dense than water
hydrogen bonds are long, hydrogen bonds broken when ice is melted, so less hydrogen bonds in water than ice. So molecules on average molecule in ice will be further apart than in liquid. Makes ice less dense. Unusual
can covalent compounds conduct electricity and why
no overall dipole is unchanged
whats the melting/boiling points of covalnet comapounds and why
intermolecular forces weak so little energy needed to break them. low boiling/melting point.
whats the solunility of covalent compounds and why
compounds with hydrogen bonds can form H bonds with water making them soluble. Molecules that aren’t polar will be insoluble.
main factor that determines boiling point
strength of london forces (unless H bonds can be made)
