chemistry topic test 2 Flashcards
list the properties of metal
good conductors of heat and electricity in solid & liquid state
shiny surface
hard
malleable
ductile
insoluble in water
reasonably high MP
very high BP
describe metallic bonding
particles arranged as a lattice of positive cations surrounded by a sea of delocalised electrons
delocalised: can move around atoms and through the lattice
explain the metallic property of heat/electricity conduction
when heated energy of cations and delocalised electrons increases
this energy is conducted along metals as cations and electrons collide, transferring electricity
when metals conduct electricity, electrons from one end of the metal cause a similar number of e- to be displaced from the other end
in sold: only electrons move
liquid: both cation and e- carry charge
explain the metallic property of malleability and ductility
bonding in metals is NON DIRECTIONAL
layers of atoms can slide over each other without destroying metallic bond
explain the metallic property of MP & BP
MP and BP indicate strength of intermolecular forces
relatively high MP and BP due to strong attraction between positive cations and mobile electrons
explain the metallic property of hardness
strength of bond is related to charge of positive cations in lattice
metals in group 2 are stronger because atoms release 2 valence electrons (instead of 1 in group 1) and form ions with a +2 charge
list the ionic properties
non conductors of electricity in solid state
good electrical conductors in molten or liquid state
hard
brittle
relatively high MP
relatively high BP
varying solubilities in water, insoluble in non-polar solvents
describe ionic bonding
ionic solid:
positive and negative ion are arranged in an orderly 3D lattice
each positive ion is surrounded by negative ions and vice versa
ions are held in fixed positions by strong ionic bonds
Explain the ionic property of conducting heat/electricity
solid: non conductors because ions are held in a fixed lattice, no mobile charged particles
molten: ions are now mobile, both positive and negative ions carry charge
aqueous: ions dissociate and are able to carry charge
Explain the ionic property of MP and BP
high MP and BP:
ionic bonding has large electrostatic forces of attraction between holding atoms together in a lattice
large amount of energy is required to overcome strong ionic bonds
Explain the ionic property of hardness
strong ionic bonding extends throughout lattice solid
scratching requires overcoming strong ionic bonds
Explain the ionic property of brittleness
ionic lattice doesn’t withstand distortion
when lattice is distorted, like charges align and repel, shattering lattice
Describe covalent molecular substances
exist only as discrete molecules
non metals only
solid, liquid or gaseous state
intramolecular forces: strong covalent bond hold atoms together within a molecule
intermolecular forces: weak forces of attraction between molecules
list the properties of CMS
non conductors of electricity in solid and liquid
some are weak/good conductors in aqueous solutions
malleable
soft
low Mp and BP
mostly insoluble in water, soluble in non-polar compounds
examples: F2, H2O, O2
explain the covalent molecular property of electricity conduction
non conductors in aq, s or l:
molecules are uncharged
electrons are held tightly within covalent bonds
**exception: some CMS react with water to form ions, and become conductors in aqueous solutions
explain the covalent molecular property of softness
weak intermolecular forces require little effort to overcome: easy to separate molecules
strong covalent bonds aren’t disrupted
explain the covalent molecular property of malleability
molecules can easily slide or be pushed
only weak intermolecular forced exist between them, these can easily be reformed
explain the covalent molecular property of BP and MP
low BP and MP:
when CMS are heated, little energy is needed to overcome weak intermolecular forces
Describe covalent network substances
solid state only
non metals only
carbon with different structures are called allotropes:
diamond and graphite
examples of CNS substances: silicon, silicon dioxide, carbon
List the properties of covalent network substances
non conductors of heat and electricity in solid and liquid state **exception: graphite
extremely brittle
extremely hard
high MP and BP
insoluble in water and most other solvents
reasonably chemically inert
Describe the bonding of covalent network substances
arranges in an infinite lattice structure
explain the CNS property of electricity/heat conduction
non conductors: no mobile electrons because all valence electrons are tied up in covalent bonds **exception: graphite
explain the CNS property of brittleness
if some bonds are broken, the rest of the lattice is placed under stress and shatters
explain the CNS property of hardness
extremely hard:
breaking strong covalent bonds requires a very large amount of energy
explain the CNS property of MP and BP
high MP and BP:
each atom is held in place by strong covalent bonds
breaking these bonds requires a very large amount of energy
explain the CNS property of solubility
insoluble in water & most other solvents:
vary large amount of energy is required to re-arrange existing bonds in any dissolving process
explain the CNS property of chemical inertness
reasonably chemically inert:
all bonding requirement are fulfilled
very large amounts of energy required to re-arrange existing bonds
Briefly describe the structure and property of diamond
structure:
each carbon atoms is attached to 4 other atoms in a 3D arrangement called a tetrahedron
properties: high MP (>3550˚C) non conductor of electricity brittle extremely hard
Briefly describe the structure and property of graphite
structure:
each carbon atoms is covalently bonded to 3 other atoms to form flat 2D sheets called graphene
one valence electrons from each carbon remain delocalised
properties:
high MP
good conductor of electricity
soft
what does the mole represent in mole/mass calculations
measure of the number of particles in a substance
1 mole of any substance contains 6.022 x 10(23) particles
what does molar mass represent in mole/mass calculations
equal to atomic, molecule and formula masses in grams
What is mass spectrometry used for
determines mass and relative abundance of each isotope present in a sample of an element
describe the process of mass spectrometry
involved 4 steps: vaporisation ionisation acceleration detection
- sample is vaporised
- electrons are fired at the sample and are used to knock off electrons from the atoms, forming ions
- ions are accelerated and are deflected through a magnetic field (heavier ions are deflected less than lighter ions)
- Ions are detected and produces a mass spectrum
list the separation techniques
sieving
filtration
evaporation
gravity separation
distillation
fractional distillation
Briefly describe the separation technique of filtration
liquid passes through filter paper (filtrate) ad solid residue is left behind
used for:
separating very fine solid particles from liquids and gases
Briefly describe the separation technique of sieving
mixture is passed through a sieve, a series of sieves may be used
based on different sizes of components, smaller particles will pass through the hole, larger particles will get caught
used for:
separating solids from liquids
e.g. straining pasta
Briefly describe the separation technique of gravity separation
2 tubes containing different mixtures are spun around at a very high speed, forcing part of the mixture to settle at the bottom of the tube
used for:
separating particles from liquids
e.g. separating fat from milk
what are the classifications of matter
pure substances: contain 1 type of particle
- elements: contain 1 type of atom e.g. Ca, O2
- compounds: contain 2 or more different types of atoms
e. g. H2O, NaCl
mixtures: contain 2 or more different types of particles
- homogenous
- uniform composition
- e.g. air, soft drinks
- heterogenous
- non uniform composition
- e.g. dirty water, paints
