bonding,structure and the properties of matter Flashcards
what is ionic bonding
ionic bonding is the electrostatic attraction between positive and negative ions.
. it is a relatively strong attraction
how are ionic compounds held together
. they are held together in a giant lattice
. it is a regular structure that extends in all directions in a substance
.electrostatic attraction between positive and negative ions holds the structure together
state properties of ionic substances
. high melting and boiling points
.do not conduct electricity when solid
.conduct when molten or dissolved in water - ions are free to move
- give 5 examples of positive ions
and 5 examples of negative ions - what is important when working out the formula of an ionic compound
positive=
.sodium
.magnesium
.Aluminium
.rubidium
negative-
.chlorine
.bromide
.sulfate
.nitrate
.hydroxide
- ionic compounds are electrically nuetral , positive and negative charges balance eachother
how are ionic compounds formed
. reaction of metal with non-metal . electron transfer occurs, metal gives away its outer shell electrons to non-metal
what is a covalent bond
covalent bond is a shared pair of electrons between two atoms
describe the structure and properties of simple molecular covalent substances
. do not conduct electricity
.small molecules
.weak intermolecular forces,therefore
.low melting and boiling points
how to intermolecular forces change as the mass of the molecule increases
they increase. this causes melting and boiling points to increase as well
what are polymers, what are thermosoftening polymers
.polymers are very large molecules , with atoms linked by covalent bonds
.a special type of polymers-
they melt/soften when heated.
.there are no bonds between polymer chains
.weak intermolecular forces ensure that the structure is solid at room temperature.
.these forces are overcome with heating- polymer melts.
what are giant covalent substances
. solid atoms covalently bonded together in a giant lattice
.high melting and boiling point - strong covalent bonds
.mostly dont conduct electricity
.diamond,graphite
silicone dioxide
describe and explain the properties of allotropes of carbon
diamond-
.four , strong covalent bonds for each carbon atom
.very hard
.very high melting point
.does not conduct , no delocolised electrons
Fullerenes-
.hollow shaped molecules
.based on hexagonal rings
.has spherical shape , simple molecular structure(buckminster, fullerene)
nanotubes-
.cylindrical fullerene with high length to diameter ratio
.high tensile strength
.conductivity
Graphine- a single layer of graphite
Graphite-
.three covalent bonds for each carbon atom
.layers of hexagonal rings
.high melting point
.layers free to slide as weak intermolecular forces between layers.
.conduct thermal and electricity due to one delocalised electron per carbon atom
.
what is metallic bonding
forces of attraction between delocalised electrons and nuceli of metal ions
describe properties of metals
. high melting/boiling point
. good conductors of heat and electricity
.mealleable,soft, (layers of atoms can slide over eachother whilst maintaining the attraction forces).
what are alloys, why are they harder than pure metals
alloys-
.mixtures of metals with other elements, usually metals
.different sizes of atoms disorts the layers, so they cant slide over eachother , therefore alloys are harder than pure metals
simple covalent properties
simple-covalent
. boiling points- low because of weak intermolecular forces between molecules.
.conductivity when solid=
poor-no ions to conduct
.conductivity when molten- poor,no ions
.general description-
mostlygases and liquids
ionic properties
boiling/melting points-
.high, because of giant lattice of ions with strong forces between oppositely charged ions
.conductivity when solid-
poor- ions cant move
.conductivity when molten- good- ions are free to move
.general description-
crystalline solids
giant covalent properties
. boiling/melting points-
high-because of many strong covalent bonds, between atoms in giant structure
.conductivity when solid- diamand and sand - poor because electrons cant move
.graphite- good as free delocalised electrons between layers can move through structure
.conductivity when molten-
poor
.general description-
solids
metallic properties
.melting/boiling points-
high- strong electrostatic forces between positive ions and delocalised electrons
.conductivity when solid-
delocalised electrons are free to move through structure
.conductivity when molten= good
.general description- shiny metal solids
what does the amount of energy needed to change state from solid to liquid , or liquid to gas depend on
the strength of the forces between the particles of the substance.
. the nature of the particles involved depends on the type of bonding and the structure of the substance
. the stronger the forces between the particles, the higher the melting and boiling points of the substance.
a pure substance will melt or boil at..
what about the mixture..
- a fixed temperature
- a mixture will melt over a range of temperatures
what are the 3 states of matter
.solid
.liquid
.gas
what is nanoscience
science that studies particles that are 1-100nm in size
state the use of nanoparticles
.medicine
.electronics
.deodrants
.sun creams
what are fine and coarse particles
. fine particles- soot - 100-2500nm diameter
.coarse particles-dust-2500-10000nm diameter
why do nanometers have different properties to those for the same materials in bulk
high surface area to volume ratio
