Bonding And Structure Flashcards
ionic bonding
electrostatic forces of attraction between oppositely charged ions
factors effecting strength of ionic bonds
- ion charges
- ionic radii
- effects the strength of attraction between oppositely charged ions
formation of ions
loss or gain of electrons
isoelectronic ion radii effects
Electron configuration remains constant
- change in nuclear charge
- change in strength of attraction between nucleus and electrons
isoelectronic
ions that have the same number of electrons
trend in atomic radii down a group
- radii increases
- ions have the same charge
- atoms get larger as they gain shells
physical properties of ions as evidence for ions
- high melting and boiling points indicate the strong electrostatic forces existing between the oppositely charged ions in ionic compounds
- ability to conduct electricity when molten or ion solution shows that mobile charge carrying particles exist in these substances
dashed line in a displayed formula
going into the page
blocked out triangle in displayed formula
coming out of the page
migration of ions as evidence for ions
a rectangle of filter paper soaked in water is placed on a slide, electrodes connected and a crystal of ionic material placed between the electrodes
covalent bonding
electrostatic force of attraction between nuclei and shared pair of electrons
dative covalent bonding
when both electrons that are shared come from one atom
physical properties of simple covalent
weak intermolecular forces between the molecules
Little energy is needed to overcome these forces
melting and boiling points are low
physical properties of giant molecular
strong covalent bonds
require a large amount of energy to overcome
high melting and boiling point
conductivity of covalent molecules
do not have free electrons
non-conductors of electricity
Graphite is exceptional in that it does have free electrons and so is a conductor
Single covalent bond strength
- change in atomic radii
- change in distance between nuclei and shared electron pair
- change in the strength of a attraction between nuclei and shared pair of electrons
sigma bond
exists directly between the two atoms; it lies symmetrically along an axis joining the two nuclei
pi bond
made up of two halves forming a double bond
expanding the octet
the process of splitting electron pairs means that an atom in a compound can have more than 8 electrons
electron pair repulsion theory
electrons are all negatively charged and so will repel each other each electron region takes up a position to minimise repulsion
electronegativity
ability of an atom with a covalent bond to attract the bonding pair of electrons
polarisation
one atom will have a greater electronegativity than the other
will have a greater pull on the electrons
distorting the electron region
cause of polar bonds
one atom has a higher electronegativity
one atom become more negative
electrons are closer to that atom