chemistry topic 2 Flashcards
why are the three types of strong chemical bonds
- Ionic
- Covalent
- Metallic
describe ionic bonding
Particles are oppositely charged ions
Between metals and non-metals
describe covalent bonding
Particles are atoms which share pairs of electrons
describe metallic bonding
Particles are atoms which share delocalised electrons
In metallic elements
and alloys
what happens during ionic bonding
- Between a metal and non-metal
- Metals LOSE electrons to form a
POSITIVE charge - Non-metals GAIN electrons to form a
NEGATIVE charge
what is an ionic compound composed of
An ionic compound composed of positive
ions (cations) and negative ions (anions).
what is Electrostatic Attraction
When oppositely charged ions are
attracted to each other
what is made during electrostatic attraction
ionic bonds
describe why things have a high melting point.
- Giant 3D ionic lattice
- there are strong electrostatic forces of attraction between oppositely charged ions
- so large amounts of energy are needed to break the bonds
why are solid ionic compounds not conductive
When solid, the ions cannot move so do not conduct electricity.
why are molten/disloved ionic compounds conductive
When molten or dissolved in water, ions
are free to move and carry charge so
conduct electricity.
when does covalent bonding occur
Covalent bonding occurs between a non-metal and a non-metal. Atoms share outer
shell electrons with each other
what is it called if Two pairs of electrons are shared between atoms
double bond
what happens when you apply heat to molecules close together
intermolecular forces of attraction are easily broken and the structure is lost
how are molecules attracted to eachother
Molecules are attracted to each other by
intermolecular forces
give features of simple covalent molecules
Low melting and boiling
points
Usually liquids or gases at
room temperature
They have strong covalent
bonds within the molecules,
but only weak intermolecular
forces between molecules
which require little energy to
break
give features of a diamonds structure on an intermolecular scale
- Each carbon atom bonded
to 4 other carbon atoms - Hard
- Strong
- Doesn’t conduct electricity
as no delocalised electrons - Strong covalent bonds
between carbon atoms
require a lot of energy to
break (high melting point)
give features of graphites structure on an intermolecular scale
- Each carbon atom bonded to 3
other carbon atoms - Weak
- Brittle
- Conducts electricity as it has
delocalised electrons which can
carry charge through the
structure - Slippery as graphite is in layers
with weak intermolecular forces
between layers
what are Fullerenes.
Hollow sphere Buckminsterfullerene
what structural feature of a metal makes it malleable
Layers can slide over each other
what structural feature of a metal makes it conductive
Delocalised electrons can move and carry heat and charge
what structural feature of a metal gives it a high boiling point
Strong force of electrostatic attraction
between electrons and metal ions
what makes alloys strong
Alloys atoms cannot slide over each other
what is an alloy
a mixture of 2 or more metals
give features of alloys
Layers disrupted due to different sized atoms
Layers cannot slide over each. Strong but not malleable
give features of pure metals
Regular pattern due to same sized atoms
Layers slide over each. Weak but malleable
what are the three states of matter
solid, liquid, gas
describe solids on an intermolecular scale
particles close together in regular
pattern, particals vibrate on the spot.
describe liquids on an intermolecular scale
particals close together in random arrangement, particals move around each other.
describe gases on an intermolecular scale
particals Far apart in random arrangement, particals move quickly.
what does the energy need to change a state of matter depend on
the strength of the forces between the
particles of the substance.
what can nanoparticles be used as
catalysts
what are the dangers of nanoparticles
- They may be able to catalyse harmful reactions in the body
- Toxic substances may be able to bind to them and enter the body
- They could enter and accumulate in our lungs and cause damage
