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Topic 1- Key concepts
Atomic Structure
Dalton model of a particle:

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Everything is made of atoms
Atoms are indestructible
All atoms of an element are identical, and
different elements have different atoms
Chemical reactions rearrange atoms
Two or more types of different atoms join
together to make compounds

Anion- negative ion
Cation-positive ion
Atom:
 A nucleus
 Contains neutrons and positive protons,
surrounded by negative electrons
 Same number of protons and electrons
 Atoms are originally neutral
 Nucleus is very small compared to overall
atom, and holds most of the mass
 Mass number- top number, protons +
neutrons
 Atomic number- number of protons
 Atoms of a given element hold the same
number of protons
o Isotopes have different number of
neutrons
 Atomic mass- average mass of atom over
isotopes, not always integer
o Depending on percentage of how
common the isotope is
The periodic table
Mendeleev:
 Newland’s theory of octaves (number of
electrons on a shell) were put in vertical
groups
 Order of atomic mass
 Similar chemical and physical properties
went into the same period
 Worked out atomic mass of missing
elements, predicted properties according to
others in the group

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Metals and non-metals are divided by a
line on the right of the periodic table

Blue=metals green=metalloids brown=non-metals
 Electrical configuration increases by one
across the table, beginning a new shell
every eight
 Each row begins another shell of electrons
Ionic bonding:
 Metal and a non-metal
o Metal loses electrons
o Non-metal gains electrons
 Electrostatic force holds opposite charged
ions together
 All ions are arranged in giant ionic lattices
 Properties:
o Solid at room temp
 High melting temp/boiling
point
o Soluble in water
 Uneven distribution of
charge, so the molecules of
ionic compounds are
attracted to uneven charge
of water
 ‘Pulls apart’ giant lattices
o Only conducts electricity as
molten/solution
 Solids have no free
electrons- insulators
 Can only vibrate
 ‘-ide’ and ‘-ate’
o ‘-ide’ has only two elements
o ‘-ate’ and ‘-ite’ contains three or
more, one being oxygen
o Furthest to the left of periodic table
comes first
Covalent bonding:
 Non-metals
 Shared pair of electrons
o I
...
oxygen needs 2
 Can be in two forms

o Simple molecular
 Hydrogen chloride
 Dihydrogen monoxide
o Giant lattice
 Diamond
 Graphite
 Graphene
 Silicon Dioxide
 Simple molecular- properties:
o Weak intermolecular forces
between smaller pairs/bonds
o Low boiling point & melting point
o Gas/liquid in room temp
o Not soluble in water
o Never conducts electricity
 Giant lattice(graphite/graphene)properties
o Solid in room temp
o High melting point & boiling point
o Not soluble in water
o Free electron- carries electricity as
solid/solution
o Weak intermolecular forces
between layers
 ‘Slides apart’ – used in
pencils
 Graphene- single layer
 Giant lattice(diamond)- properties
o Solid in room temp
o High melting point & boiling point
 Even higher than other
giant lattices
o Not soluble in water
o Fully bonded
 Harder to break all covalent
bonds
 Doesn’t conduct electricity
Fullerenes:
 ‘cage’, ‘balls’ or ‘tubes’ of carbon atoms
o i
...
c60 (Buckminster fullerene)
Polymers:
 Simple polymers are large molecules made
of chains of carbon atoms
o i
...
polyethene (a light resin used in
plastic objects like bags)
Particle representations:
 Dot and cross

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o Does not show shape
Ball and stick

o Does not show correct proportion
o Does not show how much space an
atom fills
Metallic bonding:
 Electrons are free to move around
o Delocalised
 All ions are positive
 Properties:
o High melting/boiling point
o Solid in room temp (aside from
mercury which doesn’t share
valence electrons and mimics
behaviour of smaller molecules,
therefore low MP)
o Valence electron- outer shell
electrons, outer ‘valence’ shell
o Malleable Arranged in layers, slide
and interlink just as easily
o Conducts electricity
o Still not soluble
o Ductile & Malleable
o Shiny
 Alloys- mix in another element
o Disrupts neat, regular structure
o Layers can’t slide over one another
easily
 Less malleable, stronger
Calculations involving mass
 Molecular Formula
o Actual ratio- not simplified
Empirical formula- CH2
o
Molecular formula- C2H4
o
 Relative formula mass
o Write Mr of both elements
o Times Mr by amount of moles of
element
o Add together
Mg – 24
Mg – 24

Cl- 35
...
36g
2
...
0983
0
...
0983 = 1
1

Cl- 7
...
05/35
...
199
0
...
0983 = 2
...

Elements are arranged by number of electrons in
the outer shell
...
9% argon
 0

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