Bonding

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  • Created by: lridgeway
  • Created on: 05-04-18 16:09
What key things need to be on an ionic bond dot and cross diagram?
brackets showing charge on ion and only showing outer shell of electron
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Define an ionic bond
electrostatic attraction bewteen the positive and negative ion
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How do you draw an ionic lattice?
have a 4x3 atom from with 3 back and 3 to the side. Each atom should have non of the same charge touching it
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Which ionic substance property is due to high melting-point coming from a strong electrostatic attraction?
ionic substances are solid at room temperature
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What gives ionic substances electrical properties?
when ions are free to move and flow in solution or when molten
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Why is an ionic lattice brittle?
layers slide and end upwith two positive or negative ions next to each other causing repeling and therefore breaking the structure
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Why are ionic lattices soluble?
waters polar properties stabilies and separates lattice of ions
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What would you include on a simple covalent dot and cross diagram?
show the outer shells of atoms involved on one diagram
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Define a covalent bond
the sharing of electrons to form a bond
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What kind of melting point do simple covalent molecules have and why?
low melting point due to weak intermolecular (van der waals) forces holding molecules together
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Can simple covalent molecules conduct electricity? Why/why not?
Cannot conduct electricity as they contain no free electrons
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Can simple covalent molecules dissolve?
depends on polarity of the molecule
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Define dative/coordinate bonding
both electron come from a donor species as another ionic species accepts the electrons to form a molecule (use donor/acceptor in exam)
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When does dative/coordinate bonding occur
when one species has a lone pair and one has no electrons to share
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instead of a line what is used to repersent a coordinate/dative bond?
arrow
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What is another name for giant covalent molecules?
macromolecular
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What are giant covalent molecules usually made of?
carbon atoms with strong covalent bonds
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How many other atoms does carbon bond to
4
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What are the two types of giant covalent structures we look at?
diamond and graphite
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What makes graphite different to diamond?
It only bond to 3 other carbon atoms
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What property makes graphite good for pencils and industrial lubricant and why is this a property?
Its slippery and soft due to weak bonds between layers (intermolecular/ van der waals) so layers can slide
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Can graphite conduct electricity? why/why not?
yes because delocalised electrons are present
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Why can graphite be used in strong lightweight sports equipment?
it has low density due to layers being fairly far apart
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What melting point does graphite have and why?
high due to strong covalent bonds in layers
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What melting point does diamond have and why?
very high due to strong covalent bonds
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Why is diamond used in drills and saws?
it is extremely hard
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Is diamond a good thermal conductor? why/why not?
yes because vibrations can travel easily through structure
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Can diamond conduct electricity?why/why not?
no because there are no free electrons
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What makes graphite and diamond insoluble?
the strong covalent bonds which make it difficult to break
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Define metallic bonding
electrostatic attraction between the metal ions and the sea of delocalised electrons
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Are metals good thermal and electrical conductors? why/why not?
Yes for both due to free movement of electrons and the ions ability to vibrate
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Why are metals malleable and ductile?
layers can slide over each other and not repel. malleable means can be shaped and ductile means it can be drawn very thin
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Are metal soluble and why?
No except liqiud metals due to strong electrostatic attraction
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What kind of melting point does a metal have and why?
high due to strong electrostatic attraction.
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What affects the melting point in a metal?
number of delocalised electrons per ion, the more there are the stronger atoms bonds will be and higher m-p will be. Also affected by size of ion and lattice
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Define electronegativity
the power of an atom to attract the bonding electrons (electron density) of a covalent bond towards itsself
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What does electronegativity depend on?
nuclear charge (greater), shielding (less) and distance from nucleus to outer electrons (less)
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What does electronegativity cause in bonds?
polarity
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Define polarity
the unequal sharing of electrons in a bond,
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What causes non-polar molecules?
similar electronegativites so electron sharing is equal
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What makes an atom more polar?
larger difference in electronegativities
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Which way are the bonding electrons pulled?
towards the more electronegative atom
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What can polarity cause in a molecule?
a dipole
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Define a dipole
the difference in the electron charge between two atoms
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What is used to represent difference in electron charge between two atoms?
partial charges called delta (postive and negative)
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What creates a permenant dipole?
when a charge is unevenly distributed across the whole molecule
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What decides wheter a bond has a dipole in a molecule that has several polar bonds?
its shape. if the polar bonds are symmetrical then there is no overall dipole however, is all the polar bonds are in roughly the same direction then there will be a dipole
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Name the 3 different types of intermolecular forces
hydrogen bonds, dipole-dipole (permenant), Van der Waals
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What do Van der Waals cause?
all atoms/ molecules to be atttracted to each other as induced dipoles are always getting created and destroyed
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Explain how Van der Waals forces work
electrons in charge clouds are always moving and at any particular moment there is likely to be more electrons on one side this causes a temporary dipole in the atom which can induce a dipole in a neighbouring atom (domino effect).
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What effect does change in electron cloud size have on Van der Waals?
the bigger the electron cloud the stronger the forces
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What effect does going down a group have on Van der Waals?
more electrons and as its caused by electron distortion, more electrons means greater distortion and greater force
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What effect does branching have on Van der waals?
branching creates weaker forces as molecules cant lie as close together
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Where do dipole-dipole forces occur?
between molecules with an overall dipole and are permenant
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Why does water bend towards to charged rod?
water molecules are polar, have dipolesand therefore can move so oppositely charged end to the rod is towards the rod. This only works with polar liquids and th emore polar the greater deflection of water occurs
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Which intermolecular force is the strongest?
hydrogen bond
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Which atom can hydrogen bonds occur in?
F,O,N and a hydrogen must be covalently bonded to this atom to work
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Why does hydrogen bonding occur?
the bond is so polarisedthat hydrogen has a high charge density and begins acting as an ion bonding with lone pairs
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What is important to remember when drawing hydrogen bonds?
the hydrogen bond must be 180 degrees and the lone pairs must be added with partial charges
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Why does hydrogen bonding give a very high boiling point?
extra energy needed to break bond
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Why is ice less dense than water?
more hydrogen bonds are created as water cools and a regular lattice forms, but becasuse bonds are long distances between water molecules there are more spaces in ice
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What shape has 2 electron pairs? What is the bond angle?
linear, bond angle 180 degrees
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What shape has 3 bonding electron pairs? What is the bond angle?
trigonal planar, bond angle 120 degrees
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What shape has 2 bonding and 1 lone pair of electrons? What is the bond angle?
bent (1), bond angle 118 degrees
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What shape has 4 bonding pairs of electrons? What is the bond angle?
tetrahedral, bond angle 109.5 degrees
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What shape has 3 bonding and 1 lone pair of electrons? What is the bond angle?
trigonal pyramid, bond angle 107 degrees
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What shape has 2 bonding and 2 lone pairs of electrons? What is the bond angle?
bent (2), bond angle 104.5 degrees
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What shape has 5 bonding pairs of electrons? What are the bond angles?
trigonal bipyramid, bond angles 90 and 120 degrees
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What shape has 4 bonding and 1 lone of electrons? What are the bond angles?
seesaw, bond angles 89 and 119 degrees
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What is the shape has 3 bonding and 2 lone pairs of electrons? What is the bond angle?
t-shape, bond angle 89 degrees
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What shape has 6 bonding pair of electrons? What is the bond angle?
octahedral, bond angle 90 degrees
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What shape has 5 bonding and 1 lone pair of electrons? What is the bond angle?
square pyramid, bond angle 89 degrees
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What is shape has 4 bonding and 2 lone pairs of electrons? What is the bond angle?
square planar, bond angle 90 degrees
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What are charge clouds?
an area where you have a big chance of finding an electron as electrons dont stay still in the cloud
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What is electron pair repulsion?
all electrons are negative so charge os charge clouds repel as far as possible
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Which repel more lone pair charge clouds or bonding pair charge clouds?
lone pair charge clouds which makes bond angles change based where lone pair is as they push bonding pairs closer
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Other cards in this set

Card 2

Front

Define an ionic bond

Back

electrostatic attraction bewteen the positive and negative ion

Card 3

Front

How do you draw an ionic lattice?

Back

Preview of the front of card 3

Card 4

Front

Which ionic substance property is due to high melting-point coming from a strong electrostatic attraction?

Back

Preview of the front of card 4

Card 5

Front

What gives ionic substances electrical properties?

Back

Preview of the front of card 5
View more cards

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