bonding, structure and properties of matter Flashcards
what are ions
charged particles, made when electrons lost or gained
what are metal and non metals ions called
cations (m) anions (n-m), non metals attract electrons more strongly than metals
what happens in ionic bonding?
-strong electrostatic attractions holds oppositely charged ions together in an ionic lattice
diatomic atoms:
Hydrogen, Oxygen, Bromine, Nitrogen, Chlorine, Iodine, Fluorine
ionic compounds:
giant ionic lattice very strong electrostatic forces of attraction betw opp charges ions in all directions
how to find empirical formula:
balance charges so overall is 0
properties of ionic compounds
-have high melting and boiling points due to strong electrostatic attraction betw ions. breaking them requires a large amount of energy
-most dissolve easily in water
-don’t conduct heat when solid because ions are held in fixed positions. when melted or dissolved, ions free to move so they’ll carry electric charge
dis and advantage of using:
dot and cross
3D models
ball and stick model
d&t:
-you can see electron transfer
-don’t show lattice structure, relative sizes of ions or how they are arranged
3D:
-show regular pattens and relative sizes of ions
-you can only see outer layer of lattice
b&s
-shows that crys is extended further than shown, shows pattern and relative size of ions and arrangement
-suggest that there are gaps between ions, sometimes ions not shown to scale
,
,
what is the formula of magnesium iodide?
mg forms 2+ ions and iodine forms 1- ions. to balance, two iodine is needed for each mg ion. so it’s MgI₂
what is covalent bonding?
describe
occur between non-metals
pair of elec shared betw two atoms.
+ charged nuclei of bonded atoms are attracted to the shared pair of elc by electrostatic forces , thus very strong bonds,
what is a double co bond?
two pairs of electrons shared between two atoms
what is a simple molecule? do they conduct electricity?
-made up of only a few atoms joined by covalent bonds
-they don’t conduct elec
-bcs no charged particles
properties of simple molecules
-don’t conduct electricity in any state, there are no ions or free electrons
-have low melting and boiling points (because of weak intermolecular forces which need to be overcome in order to melt, which doesn’t require much energy) so mostly gasses at room temperature, but can be solids
when is melting point higher?
larger or smaller molecules?
when the molecule is larger, intermolecular forces are stronger thus more energy required to break them
what is a polymer?
a substance ….
a substance consisting of long molecules
made of repeating sections
the atoms are joined by covalent bonds
how do you write molecular formula of polymer?
write molec formu of repeating unit by counting no. of atoms of each element it contains, put brackets around it and put an ‘n’ after the brackets
properties of polymer:
-higher melting and boiling points than simple covalent as intermollecular forces are stronger betw larger polymer molecules.
-most are solid at room temp
-however b&m points lower than ionic and covalent as inter mol is still weaker, so generally lower than cov and ionic
properties of giant covalent structures:
-have high melting and boiling points
-similar to lattices but charged ions
-ex diamonds and graphite, made up of only carbon atoms
what is an allotrope?
different structural forms of the same element in the same physical state
properties of graphite:
-each carbon atom only forms three covalent bonds,
-sheets of carbon atoms arranged in hexagons,
-no co bonds between layers, only held by weak intermolecular forces, so free to move,
-makes them soft and slippery ideal for lubricating material,
-high melting point,
-each carbon atom has one delocalised electron, graphite conducts electricity and thermal energy
properties of diamond:
-each carbon atom forms four covalent bonds with other carbon atoms,
-rigid structure,
-hard to break covalent bonds,
-no free ions or electrons so no electricity
properties of graphene:
-single sheet of graphite, very tough but light so adds to composite material durability without weight,
-can conduct electricity, high potential to be used in electronics
what is a fullerene?
hollow molecules of carbon, shaped like tubes or balls. mainly made up of carbon atoms arranged in hexagons,
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can also be pentagons or heptagons
-buckminsterfullerene first one to be discovered, molecular structure of C60 and forms hollow sphere
what is a nanotube?
-fullerenes which are tiny carbon cylinders. ratio between length and diameter of nanotube very high, good conductors of electricity.
uses of fullerenes
-med
-drug
-elec
-size
-in medicine
can be used to cage other molecules. fullerene structure forms around other molecules. this can be used to deliver a drug into the body in a highly controlled way
-as catalysts
fulls have large surface area, individual catalyst molecules attached to the fullerenes
-as lubricants
-in electronics
very small, can conduct electricity
what is graphene:
a single sheet of graphite, carbon atoms joined together in hexagons
fullerenes:
hollow molecules made of carbon atoms, arranged rings
why are alloys more useful than pure?
diff atoms diff sizes, distort layers, difficult to slide over each other
structure of a metal
giant struc, atoms reg arrange by sea of delocalised elec
how to calc moles with mass n mr
mass/ mr
group 1 (alkali metals)n properties
-react elemtnts
-low density
-soft
-low melting point
>react vigorously with h20, o2, and g7 elements
what do alkaline metals form when reacting with h2o?
a metal hydroxide + hydrogen gas
what do alkaline metals form when reacting with oxygen?
diff ones for sodium
potassium:
lithium:
metal oxide
-lithium oxide
-potassium peroxide (k2o2) and pott. superoxide (ko2)
-sodium oxide (na2o) and sodium peroxide (na2o2)
equations for:
a sodium atom losing an electron
a chlorine atom gaining an electron
a magnesium atom losing two electrons
Na —-> Na+ + e-
Cl + e- —-> Cl-
Mg —-> Mg2+ + 2e-
properties of ionic bonding
-what it is and what happens etc.
-transfer of electrons from metal to non metal
-opp charged ions, attracted by strong electrostatic forces
-forms really strong ionic bond
properties of an ionic lattice
-very high melting an bp’s, strong elecstat forces require loads of energy to break
-can’t conduct elec when it is solid as there are no ions able to move around, when molten, ions can move and carry a charge
properties of an ionic lattice
-very high melting an bp’s, strong elecstat forces require loads of energy to break
-can’t conduct elec when it is solid as there are no ions able to move around, when molten, ions can move and carry a charge
formula of
hydroxide ion
sulfate ion
nitrate ion
carbonate ion
ammonium ion
Hydroxide: OH^-
Sulphate: SO_4^2-
Nitrate: NO_3^-
Carbonate: CO_3^2-
Ammonium: NH_4^+
uses of nanoparticles
-in catalysts
-medicine
-circuits
-silver n.p, have antibacterial properties, can reduce chance of infection
issues with n.particles
-new
-not understood yet
-concerns of harm to body
-and environment
why are simple molecules easy to melt?
-strong covalent bonds betw atoms
-but weak intermollecular forces
-don’t require a lot of en. to be broken
the more …….. forces a molecule has, the …… the overall attraction is
-intermollecular
-stronger
properties of giant covalent structures
-very high m.p’s and b.p’s
-very strong
-don’t conduct elec even when molten
(except graphite)
name three giant co structures
-diamond
-graphite
-silicon dioxide
what happens when metals bond together
regarding charges and electrons
-they give up their electrons and share them wiv e/o
-the atoms are now all positively charged
what makes metallic bonding strong
-strong electrostatic attraction betw the delocalised electrons and +vely charged ions
-these forces hold evrthn together in a reg. structure
properties of pure metals
-good conductors of electricity & heat
-high m & bp’s
-malleable
what is an allotrope
different structural form of the same element in the same physical state
giant covalent structures (diamond, graphite) are made of …….. …….. ….. ……. …….. ……
which makes it very ……
regular lattice of covalently bonded atoms
strong
structure of diamond:
each carbon atom co bonded to 4 other c atoms,
very strong and high melting point
doesn’t conduct electricity as no free electrons or ions
structure of graphite
each carbon atom co bonded to 3 other c atoms,
atoms arranged into hexagons, form large flat sheets and arranged on top of e/o to form layers
layers held by weak intermol forces, can slide over e/o making it soft
still has high melting point
conducts electricity and heat as it has delocalised electrons
what are fullerenes made of
sheets of graphite
how are fullerenes used in medicine
-scientists can form spheres around other molecules (drugs),
acts like a cage
can deliver these drugs to certain parts of the body
because fullerenes have a large sa : vol ratio….
they can be used as industrial catalysts
uses of nanotubes
-in tech bcs of elec conduction
-adds strength to materials because of high length : diameter ratio, w/o adding weight to material
Explain why sodium oxide has a high melting point. (ionic structure)
giant structure
(with) strong (electrostatic) forces of attraction between (oppositely charged) ions
(so) large amounts of energy are needed to break the bonds / forces
