bonding and structure Flashcards
define ionic bond
the electrostatic attraction between positive and negative ions
describe and explain the conductivity of ionic compounds under different states
doesnt conduct when a solid because the ions are fixed in a lattice and arent free to move so cant carry a charge
conducts when molten or dissolved because the ions are free to move so can carry a charge
why are ionic compounds soluble
as water molecules are polar so will surround each ion
why are some ionic compounds more soluble then others
greater charge difference meaning stronger attractions which is less easily overcome
why do ionic compounds have high melting and boiling points
strong electrostatic attraction between negative and positive ions which requires lots of energy to overcome
define covalent bond
the strong electrostatic attraction between a shaired pair of electrons and the nuclei of the bonded atoms
define bond enthalpy
a measurement of covalent bond strength
what is a coordinate/dative covalent bond
a shared pair of electron in which both electrons comes fron the same atom
give three bond angles from largest to smallest
bond angle between lone pairs
bond angle between a lone pair and a bonding pair
bind angle between bonding pairs
what do lone pairs repel by and why
2.5 as they are closer to the nucleus and take up more space
describe a linear shape
2 bp
0 lp
180 degrees
describe trigonal planar
3 bp
0 lp
120 degrees
describe tetrahedral shape
4 bp
0 lp
109.5 degrees
describe triogonal pyramidal shape
3 bp
1 lp
107 degrees
describe non linear shape
2 bp
2 lp
104.5 degrees
describe octehedral shape
6bp
0lp
90 degrees
how to tackel a explain the shape of molecule question
state the numbee of bp and lp
state electrons repel and try to get as far apart as possible
state lp repel more then bp or that they repel equally if no lp
state shape of molecule and bond angle
why are chemists able to predict the shape of molecules
as electrons repel and the shape is determined by number of lp and bp
define electronegativity
the ability of an atom to attract electrons in a covalent bond to itself
when can you tell a bond is polar
if the two atoms are different elements
how can a molecule be non polar but contain polar bonds
as it’s symmetrical so the dipoles cancel each other out
how can you work out if a molecule is symmetrical
generally if it doesnt have any lp
what are permanent dipole dipole interactions
electrostatic force of attractuon between polar molecules
does every structure have london forces
no lattices dont
describe induced dipole dipole interactions
unequal distribution of electrons
temporary/ instantaneous dipoles
induces dipoles in nearby molecules leading to attraction
why does the strength of induced sipole interaction increase down groups
the number of electrons increases
stronger dipoles
stronger attractions
which electronegative elements will hydrogen bonding happen with and why
F O N
they are the most electronegative and most dense in electrons
give 3 reasons why water has a higher mp and boiling point to structurally similar compounds
hydrogen bonding provides it with stronger intermolecular forces
can form up to 4 hydrogen bonds
oxygen is the second most electronegative element meaning stronger hydrogen bonds
give and explain 2 anomalous properties of ice
ice is less dense then water as the molecules are held apart by hydrogen bonds in an open lattice
it has a higher mp then expected as hydrogen bonding provides it with stronger intermolecular forces
what cause high surface tension in water
hydrogen bonding leading to a strong and flexable lattice structure
what can polar and non polar molecules dissolve in
likes dissolve likes
what are the strongest to weakest intermolecular forces
hydrogen bonds
permanent dipole dipole
london forces
why is a p block element considered a p block element
its outer electron is in the p sub shell
or
as its highest energy electron occupies the p subs shell
why wont all of CO2 be released from a reaction involving a solution
it is soluble in water
