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topic 1 Key concepts in chemistry (ionic bonding ((Hydroxide ->…
topic 1 Key concepts in chemistry
nucleus containing protons and neutrons, surrounded by electrons
proton +1 -- 1
neutron 0 -- 1
electron -1 -- 1/1836
Atoms are neutral and the charges on a proton are +1 and on an electron are -1 therefore amount of protons = amount of electrons, so that the charges cancel
Mass (nucleon) Number = number of protons + neutrons
isotopes - the same element but with a different number of neutrons
Atomic (proton) Number = number of protons (= number of electrons
Mendeleev ordered his table in order of atomic mass. Left gaps for elements that he thought had not been discovered yet. v
Elements are arranged in order of atomic (proton) number (bottom number) and so that elements with similar properties are in columns, known as groups
Elements in the same group have the same amount of electrons in their outer shell, which gives them similar chemical properties.
ionic bonding
Metals + nonmetals
Metal atoms lose electrons to become positively charged ions (cation))
Nonmetal atoms gain electrons to become negatively charged ions (anion
group 2 metals will lose 2 electrons and form +2 ions
this means group 1 metals will lose 1 electron and form +1 ions
group 6 nonmetals will gain 2 electrons and form 2- ions
group 7 nonmetals will gain 1 electron and form 1- ions
-ide means the compound contains 2 elements (one is the nonmetal -ve ion)
-ate means the compound contains at least 3 elements, one of which is oxygen
Hydroxide -> involves OH1- ion (e.g. sodium hydroxide: NaOH)
Oxide -> involves O2- ion (e.g. sodium oxide: Na2O)
Halide -> involves a -1 halide ion (e.g. sodium chloride NaCl)
Nitrate -> involves NO31- ion (e.g. sodium nitrate: NaNO3)
Carbonate -> involves CO32- ion (e.g. sodium carbonate: NaCO3)
Sulfate -> involves SO42- ion (e.g. sodium sulfate: NaSO4)
giant ionic lattice
strong electrostatic forces
high melting point
high boiling point
melted or dissolved in water they conduct electricity due to free ions to carry current and they do not conduct electricity as solids, because the ions are fixed
Atomic number = proton number = number of protons
metals
giant structures of atoms arranged in a regular pattern
electrons in the outer shell of metal atoms are delocalised and so are free to move through the whole structure.
most metals have high melting and boiling points
They can conduct heat and electricity because of the delocalised electrons in their structures.
The layers of atoms in metals are able to slide over each other, so metals can be bent and shaped
insoluble in water- but some will react with it instead
covalent bonding
non metals
When atoms share pairs of electrons, they form covalent bonds. These bonds between atoms are strong.
forms molecules
giant covalent structures
very high melting point
strong forces
simple covalent compounds
low boiling and melting points.
intermolecular forces increase with the size of the molecules
don’t conduct electricity
In diamond, each carbon is joined to 4 other carbons covalently.
It’s very hard, has a very high melting point and does not conduct electricity.
cutting tools
In graphite, each carbon is covalently bonded to 3 other carbons
forming layers of hexagonal rings, which have no covalent bonds between the layers.
The layers can slide over each other due to no covalent bonds between the layers, but weak intermolecular forces.
Meaning that graphite is soft and slippery
One electron from each carbon atom is delocalised.
This makes graphite similar to metals, because of its delocalised electrons.
It can conduct electricity – unlike diamond.
electrode
lubricants
Graphene - Single layer of graphite - Has properties that make it useful in electronics and composites
Carbon- form fullerenes with different numbers of carbon atoms - Molecules of carbon atoms with hollow shapes - based on hexagonal rings of carbon atoms - contain rings with five or seven carbon atoms - Buckminsterfullerene (C60), which has a spherical shape
Carbon nanotubes - Cylindrical fullerenes with very high length to diameter ratios - Their properties make them useful for nanotechnology, electronics and materials
Examples of uses - lubricants - to deliver drugs - Nanotubes can be used for reinforcing materials, for example tennis rackets.
polymers
very large molecules
strong covalent bonds
solid at room temp