Studied by 0 peopleDelocalised electrons
an electron that is able to move freely and carry charge
Positive metal ions are
Metal atoms that have lost their outer electrons
Lattice
Regular arrangement of particles
Giant structure
A huge 3D network of atoms or ions
Electrostatic forces of attraction
Strong forces of attraction between oppositely charged particles
Metallic bonding
A lattice of positive metal ions surrounded by delocalised outer electrons, held together by strong electrostatic forces of attraction
Melting and boiling points of metallic substances
high as strong electrostatic forces between positive metal ions and negative delocalised electrons
Reason for metals being malleable
Layers of metal ions can slide over each other
Reason alloys are harder than pure metals
Different sized atoms disrupt the layers of ions, preventing layers from sliding
Usefulness of pure metals
Too soft for most uses
Reason metals conduct heat well
delocalised electrons can transfer heat energy quickly
Reason metals conduct electricity well
delocalised electrons can carry electrical charge through the structure.
24 carat gold
pure gold
Gold used in jewellery is
Usually an alloy with silver, copper and zinc
18 carat gold
An alloy containing 75% gold
12 carat gold
An alloy containing 50% gold
Giant structure
A three-dimensional network of atoms or ions
Lattice
Regular arrangement of particles.
Bonding in giant covalent structures
Covalent bonding
Covalent bond
A shared pair of electrons
States of giant covalent substances at room temperature
Solid
Melting points of giant covalent substances
Very high
Bonds broken when giant covalent structures are melted
Covalent bonds
Examples of giant covalent structures
Diamond, graphite, silicon dioxide
Reason for giant covalent structure's high melting point
Many strong covalent bonds require lots of energy to break
Solubility of giant covalent substances
Insoluble
Formula of silicon dioxide
SiO2
Uses of diamond
Cutting tools and jewellery
Uses of graphite
Pencil leads, lubricants
Number of bonds between atoms in graphite
3
Properties of diamond
Translucent, Hard, High melting point, Does not conduct electricity
Properties of graphite
Soft, Slippery, good conductor of heat and electricity
Reason graphite is soft
Weak forces between layers which can slide over each other.
Reason graphite conducts electricity
One spare electron is delocalised and can carry charge through the layers
Molecule
Two or more atoms held together by covalent bonds
State of molecular substances at room temperature
Liquids or gases
Van der Waals forces
Weak forces of attraction between molecules
Melting and boiling points of molecular substances
Low as Van der waals forces are weak.
Trends in Van der Waals
The larger the molecule the stronger the Van der Waals
Electrical conductivity of molecular substances
Low conductivity
Reason for electrical conductivity of molecular substances
Molecules are neutral
Covalent bonds
A shared pair of electrons
Solubility of small molecules
Insoluble in water
Soluble molecules
Hydrochloric acid, ammonia
Reason some molecules are soluble
They react with water
Giant ionic lattice
huge 3D regular structure held together by the electrostatic forces of attraction between positive and negative ions
Melting and boiling points of ionic substances
high
Reason for melting and boiling points of ionic substances
Strong electrostatic forces between opposite ions need lots of energy to break
Movement of ions in a solid
Ions vibrate around fixed positions
Molten
Made liquid by heat
Movement of ions when molten
Ions can move past each other
Movement of ions in solution
Ions break apart and move freely
Conductivity of solid ionic compounds
don't conduct
Reason for conductivity of solid ionic compounds
Ions are fixed in place
Conductivity of molten/dissolved ionic compounds
good conductors
Reason for conductivity of liquid/dissolved ionic compounds
Ions are free to move and carry charge
Electrostatic force of attraction
attractive force between oppositely charged particles
Number of bonds between atoms in diamond
4
Allotrope
Different forms of the same element
Number of bonds between atoms in graphite
3
Properties of graphite
Soft, Slippery, good conductor of heat and electricity
Properties of graphene
Very strong and flexible, good thermal and electrical conductor, nearly transparent
Reason graphene conduct electricity
One spare electron is delocalised and can carry charge through the layer
Graphene
A single layer of graphite one atom thick.
Uses of graphene
Electronics and solar cells
Reason graphene is strong
Strong covalent bonds between atoms need lots of energy to break
Carbon outer shell electrons
4
Carbon maximum covalent bonds
4 - sharing all its outershell electrons
Reason for metals high melting and boiling points
strong electrostatic forces between positive metal ions and negative delocalised electrons
Reason metals being malleable
layers of ions can slide over each other
Reason alloys are harder than pure metals
Different sized atoms disrupt the layers of ions, preventing layers from sliding
Usefulness of pure metals
Too soft for most uses
Reason metals conduct heat well
Delocalised electrons can transfer heat energy quickly.
Reason metals conduct electricity well
Delocalised electrons can carry electrical charge through the structure.
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