4.1 - covalent bonding Flashcards
what is the formula for nitrate
NO₃ -1
what is the formula for hydroxide
OH -1
what is the formula for sulphate
SO₄ -2
what is the formula for carbonate
CO₃ -2
what is the formula for ammonium
NH₄ +1
what is the formula for ammonia
NH₃
what types of elements form ionic bonds
metals and non-metals
where is the start of the staircase that splits the metals and the non-metals
in between aluminium (Al) and boron (B)
what is meant by the term ionic bonding?
the strong electrostatic attraction between the positive and negative ions
what type of structure do ionic compounds form?
giant ionic lattice
give one property of an ionic compound and explain it
high melting point -
- giant ionic lattice
- strong electrostatic attraction between positive and negative ions
- therefore require immense energy to overcome
what is a covalent bond?
the strong electrostatic attraction between pairs of shared electrons and positive NUCLEI
what types of elements form covalent bonds?
non-metals
what does - mean in H - Cl
1 pair of shared electrons therefore single (1) covalent bond
what does = mean in O = O
2 pairs of shared electrons therefore double (2) covalent bonds
what is the only thing we need to know about silicon dioxide
it is giant covalent
what does graphite, coal and diamond have in common in terms of elements
all made from pure carbon
explain why giant covalent substances have a high melting point
many strong covalent bonds therefore requires energy to break (only time you can break bonds)
explain the conductivity of graphite
CONDUCTIVE:
- delocalised electrons are free to move
-each carbon is bonded to 3 others (therefore there are delocalised electrons which are free to move)
explain the conductivity of diamond
NOT CONDUCTIVE:
- no delocalised electrons and no ions
is graphite hard or soft and explain why
SOFT:
- layers can slide over each other
is diamond hard or soft and explain why?
HARD:
- each carbon is bonded to 4 others (therefore very hard)
what is a use for diamond?
drill bits
(if don’t remember say cutting glass)
what is a use for graphite?
solid lubricant
what structure does metallic bonding create?
giant metallic lattice
what structure does ionic bonding create?
giant ionic lattice
what structures do covalent bonding create?
giant covalent substances
simple molecular substances
explain the melting point of simple molecular substances
- low melting point
- weak intermolecular forces require little energy to overcome
explain the relationship between relative molecular mass and boiling point
- as relative molecular mass increases, boiling point increases
- because the intermolecular forces are getting stronger
- therefore require more energy to overcome
what is an example of a simple molecular substance
C60 fullerene
the boiling point of C60 fullerene is 600°C - this is low, but is higher than other simple covalent molecules. Explain why C60 fullerene has a boiling point of 600°C
- it has more atoms therefore has a higher molecular mass
- therefore stronger intermolecular forces
- therefore, higher boiling point/melting point
what is a use of C60 fullerene
drug delivery (hollow)
graphite is naturally occurring form of carbon
explain why graphite is soft and conducts electricity
refer to structure and bonding in your answer
- graphite is a giant covalent structure
- graphite is arranged in layers that can slide over each other therefore it is soft
- each carbon has bonded to 3 others
- therefore there are delocalised electrons that can move therefore it conducts electricity
explain why a giant ionic lattice is an insulator when solid
ions are fixed in place in lettuces therefore ions can’t move
explain why a giant ionic lattice is a conductor when molten or dissolved
ions are free to move when aqueous
what types of elements form metallic bonds?
metals
describe the bonding in a metallic bond
strong electrostatic attraction between the positive metal ions and delocalised electrons
is a metallic lattice a conductor, explain why
yes - delocalised electrons are free to move
is a metallic lattice malleable, explain why
yes - layers/rows of (positive) ions can slide over each other (therefore they are ductile and can be pulled into wires)
define an alloy
a MIXTURE of a METAL and ANOTHER ELEMENT
alloys are harder than pure metals because:
- different sized atom
- disrupts layers/rows of ions
- therefore can’t slide over each other
alloys are harder than pure metals, refer to the structure of both metals to explain why
- pure metals are soft - layers can slide over each other
- alloys always contain another atom/element that is a different size
- which disrupts the regular structure
- therefore layers cannot easily slide over each other
what types of elements form covalent bonds?
non-metals
explain why simple molecular structures are insulators
no delocalised electrons or ions (particles are not charged)
explain why ionic lattice are insulators when solid
- ions are not free to move
explain why ionic lattice are conductors when liquid or aqueous
bonds break
therefore ions are free to move
what can a metal do that other elements can’t do when solid
conduct electricity
is the melting point high or low in a giant ionic
high
is the melting point high or low in a giant covalent
high
is the melting point high or low in a simple molecular
low
is a giant ionic soluble in water
usually yes
is a giant covalent soluble in water
no
is a simple molecular soluble in water
usually no
can a giant ionic conduct electricity
only when molten or dissolved/aqueous
can a giant covalent conduct electricity
only graphite
can a simple molecular conduct electricity
NO
graphite is a naturally occurring form of carbon
explain why graphite is soft and conducts electricity
refer to structure and bonding in your answer
- graphite is a giant covalent substance
- soft -> arranged in layers
-> that can slide over
each other - conduct electricity -> each carbon atom is bonded to 3 others
-> therefore it has delocalised electrons
-> which are free to move
the boiling point for fluorine, chlorine and bromine increase in temperature, explain the trend in boiling points
- boiling point increases
- they are simple molecules so have weak intermolecular forces
- down the group, the intermolecular forces get stronger and require more energy to overcome because the molecules get bigger
explain why diamond has a much higher melting point in C60 fullerene refer to structure and bonding in your answer (5marks)
diamond:
-> giant covalent structure
-> lots of strong covalent bonds
-> require immense energy to overcome
C60 fullerene:
-> simple molecule
-> therefore it has weak intermolecular forces
-> which require less energy to overcome
