Term
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Definition
Ionic Bonding
Metal + Non-metal: electrons in the outer shell of the metal atom are transferred
● Metal atoms lose electrons to become positively charged ions
● Non-metal atoms gain electrons to become negatively charged ions
● Ions – Atoms that have lost or gained electron/electrons.
● Dot and Cross Diagram |
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Term
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Definition
Ionic compounds
● A giant lattice structure of ions.
● Held together by strong electrostatic forces of attraction between oppositely
charged ions
● The forces act in all directions in the lattice, and this is called
ionic bonding.
● They have high melting and boiling points, because a lot of energy is required to
break the many strong bonds.
● When melted or dissolved in water, ionic compounds conduct electricity because
the ions are free to move and carry current. But they can’t conduct electricity
when solid because the ions are fixed in place. |
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Term
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Definition
Covalent bonding
● When atoms share pairs of electrons, they form covalent bonds. These bonds
between atoms are very strong.
● Some covalently bonded compounds consist of small molecules e.g. HCl, H2, O2,Cl2, NH3,CH4.
● Some have very large molecules, such as polymers.
● Some have giant covalent structures (macromolecules) e.g diamond, silicon
dioxide. |
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Term
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Definition
Metallic bonding
● Metals consist of giant structures of atoms arranged in a regular pattern.
● The electrons in the outer shell of metal atoms are delocalised and so are free to
move through the whole structure.
● The sharing of delocalised electrons gives rise to strong metallic bonds. |
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Term
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Definition
Polymers
● Have very large molecules
● Atoms in the polymer molecules are linked to other atoms by strong covalent
bonds
● Inter-molecular forces between polymer molecules are relatively strong and so
these substances are solids at room temperature |
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Term
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Definition
Giant Covalent Structures
● Substances that consist of giant covalent structures are solids with very high
melting points.
o All of the atoms in these structures are linked to other atoms by strong
covalent bonds.
▪ These bonds must be overcome to melt or boil these substances.
● examples include: diamond and graphite (forms of carbon) and silicon dioxide
(silica) |
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Term
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Definition
Properties of metals and alloys
● Metals have giant structures of atoms with strong metallic bonding.
● Most metals have high melting and boiling points.
● The layers of atoms in metals are able to slide over each other, so metals
can be bent and shaped, which can make them less useful for certain
things
● Alloys are made from 2 or more different types of metals.
● The different sized atoms distort the layers in the structure, making it
harder for them to slide over each other. So alloys are harder than pure
metals. |
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Term
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Definition
Metals as conductors
● Good conductors of electricity because the delocalised electrons in the metal
carry electrical charge through the metal
● Good conductors of thermal energy because energy is transferred by the
delocalised electrons |
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Term
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Definition
Diamond
● In diamond, each carbon is joined to 4
other carbons covalently.
o It’s very hard, has a very high melting point
and does not conduct electricity. |
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Term
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Definition
Graphite
● 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.
● It can conduct electricity – unlike Diamond, because the delocalised
electrons can move |
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Term
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Definition
Graphene
● Single layer of graphite
● Has properties that make it useful in electronics and composites
● graphene is very strong because atoms within its layers are very
tightly bonded and it is also elastic because the planes of atoms can
flex relatively easily without the atoms breaking apart. |
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Term
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Definition
● Nanoparticles are 1-100 nanometers across.
● They contain a few hundred atoms.
● Nanoparticles, are smaller than fine particles (PM2.5), which have diameters
between 100 and 2500 nm (1 x 10^-7 m and 2.5 x 10^-6 m). |
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Term
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Definition
● As the side of cube decreases by a factor of 10 the surface area to volume
ratio increases by a factor of 10
● Nanoparticles involve fullerenes.
● A nanoparticle has different properties to the ‘bulk’ chemical it’s made from,
because of their high surface area to volume ratio. It may also mean that
smaller quantities are needed to be effective than for materials with normal
particle sizes. As fullerenes have different properties to big lumps of carbon. |
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Term
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Definition
| Catalysts, Sensors, Building materials, Cosmetics, Lubricant coatings, Smaller electrical circuits. |
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