Bonding Flashcards
When 2 different ______ join together, you get a compound.
elements
______ bonding is when ions are held together by electrostatic attraction
ionic
________ attraction holds positive and negative ions together - it is very strong
electrostatic
The overall charge of any compound is ________
zero
Magnesium chloride contains Mg2+ and Cl- ions
What would the balanced formula be for this
MgCl2
Sodium chloride is an example of a _____ _____ _______ structure
giant ionic lattice
Ionic compounds conduct electricity when…
they are molten or dissolved as there are free electrons and ions are free to move
Ionic compounds have _____ melting points
high because they are held together by strong electrostatic forces which needs a lot of energy to overcome.
Ionic compounds tend to _______ in water
dissolve as water is polar and the charged parts pull ions away from the lattice causing it to dissolve.
What type of bond holds molecules together?
strong covalent bonds
What does a single covalent bond share?
a pair of electrons
Covalent bonding happens between 2 _____________
non metals
Carbon atoms can form what type of structure due to them forming 4 strong covalent bonds?
giant covalent structure
How are the carbon atoms arranged in graphite?
sheets of flat hexagons covalently bonded with 3 bonds each. the fourth outer electron of each carbon atom is delocalised
Give examples of the properties of graphite
- weak bonds between the layers so easily broken so sheets can slide over eachother
- delocalised electron carry a charge so graphite is an electrical conductor
- low density so can be used to make strong lightwewight equipment
- high melting point due to strong bonds
-insoluble in any solvent
In diamond, each carbon atom is covalently bonded to ____ other carbon atoms and arrange themselves in a _________ shape
4
tetrahedral
Give examples of the properties of diamond
- very high melting point
- hard
- good thermal conductor
- cant conduct electricity as all electrons are held in localised bonds
- wont dissolve in any solvent
- can be cut
define dative covalent bond and what is it represented by
dative covalent bond is where both electrons come from one atom
represented by an arrow pointing away from the donor atom
electron charge clouds repel each other, give order of repulsion from highest to lowest
lone to lone
lone to bonding
bonding to bonding
how to work out how many electron pairs a shape has?
take the central atom
work out how many electrons in outer shell
add one to this number for every atom it is bonded to
divide by 2 to find number of electron pairs
compare electron pairs to number of bonds to find the number of lone pairs and bonding pairs
shapes with 2 electron pairs
linear - no lp
shapes with 3 electron pairs
trigonal planar - no lp
shapes with 4 electron pairs
tetrahedral - no lp
trigonal pyramidal - 1 lp
v shaped - 2 lp
shapes with 5 electron pairs
trigonal bipyramidal - no lp
seesaw - 1 lp
t shaped - 2 lp
shapes with 6 electron pairs
octahedral - no lp
square planar - 2 lp
define electronegativity
an atoms ability to attract the electron pair in a covalent bond
which element is most electronegative ?
fluorine
in a covalent bond between two atoms of different electronegativities, the bonding electrons will be pulled toward the more electronegative atom. this makes the bond ____
polar
In a polar bond, the difference in electronegativity between the two atoms causes a permanent _____
dipole
Define dipole
a difference in charge between the two atoms caused by a shift in electron density in the bond
What happens to a bond when electronegativity increases?
becomes more polar
In a substance made up of molecules that have permanent dipoles, there will be weak ________________ _____ of attraction between + and - charges on neighbouring molecules
electrostatic forces
Where are Van der Waals forces found?
between all atoms and molecules
How are VDW created?
Electrons in charge clouds are moving really quickly. At any moment the electrons in an atom are more likely to be at one side - this would create a temporary dipole. The dipole can cause another temporary dipole in the neighbouring atom/ other direction. They are then attracted to each other.
In a solid at room temperature, what forces are holding them together in a lattice?
Van der Waals
What is the strongest type of intermolecular force?
Hydrogen bonding
rule for hydrogen bonding?
H bonds with N, O, F
Examples of molecules with hydrogen bonding
water and ammonia
properties of substances with hydrogen bonding
higher bp and mp
more energy needed to break bonds
why is ice less dene than liquid water?
As liquid water cools to form ice, the molecules make more H bonds and arrange into a regular lattice structure.
In this, the H2O molecules are further apart on average than molecules in liquid water so ice is less dense.
Metals exist as giant metallic lattice structures and have a _________ ______ ‘sea’
delocalised electron
describe metallic bonding
The + metal ions are attracted to the delocalised - electrons. They form a lattice of closely packed positive ions in a sea of delocalised electrons.
properties of metals
high mp due to electrostatic attraction
the more there are, the stronger the bonding so higher mp
good thermal conductors as the delocalised electrons can pass kinetic energy to eachother
good electrical conductors because the delocalised electrons can move and carry a charge
metals are insoluble because the strength of the metallic bonds
What do you need to overcome to melt or boil a simple covalent compound?
intermolecular forces
you dont need to break the much stronger covalent bonds that hold the atoms together - this is why simple covalent compounds have relatively low mp and bp
A substance will only conduct electricity if it contains ______ particles that are ____ to move.
charged
free
As water is a polar solvent, what type of particles dissolve well?
polar or charged
