Unit 1 Flashcards
metallic bonding
high MPs
good conductors of electricity
high MPs
good conductors of electricity
metallic bonding
covalent molecular
strong covalent bonds between atoms
weak LDFs between molecules
strong covalent bonds between atoms
weak LDFs between molecules
covalent molecular
covalent network
strong covalent bonds between atoms
very high MPs
carbon (as diamond and graphite), silicon, boron
strong covalent bonds between atoms
very high MPs
carbon (as diamond and graphite), silicon, boron
covalent network
what does strong covalent bonds mean for MPs
higher MPs
monatomic elements
nobles gases
weak LDFs
MPs increase as you go down the group
LDF strength increases as the ______ __ _______ increases
LDF strength increases as the number of electrons increases
LDF strength __________ as the number of electrons increases
increases
what does stronger LDFs mean for MPs
higher MPs
what should you refer to when comparing MPs
bonding, forces
what is covalent radius a measure of
the size of an atom
what is the measurement of the size of an atom
the covalent radius
what is the covalent radius
half the distance between the nuclei of the two covalently bonded atoms of an element
half the distance between the nuclei of the two covalently bonded atoms of an element
what is the covalent radius
going across a period, covalent radius _______
decreases
going ______ __ _______, covalent radius decreases
period
going down a group, covalent radius ________
increases
going _____ __ ______, covalent radius increases
down a group
going across a period, the nuclear charge ______
increases
going ______ _ _____, the nuclear charge increases
going across a period, the nuclear charge increases
going across a period, the nuclear charge ______
increases
going across a period, the number of filled electron shells _____ ___ _____
stays the same
going _____ ___ ______, the number of filled electron shells stays the same
across a period
what does an increase in nuclear charge mean
electrons being more strongly attracted to the nucleus
–> covalent radius decreases
as you go down a group, an extra ___ __ _____ is added
shell of electrons
as you go _____ ___ ______, an extra shell of electrons is added
down a group
why does covalent radius increase as you go down a group
an extra shell of electrons is added
what does an extra shell of electrons is added as you go down a group mean for covalent radius
the covalent radius increases
shielding effect
Each extra layer of electrons shields outer electrons from the positive nucleus so that the outer electrons are less strongly attracted to the nucleus
Each extra layer of electrons shields outer electrons from the positive nucleus so that the outer electrons are less strongly attracted to the nucleus
shielding effect
going down a group, the electronegativity __________
decreases
going ______ ____ __ ___, the electronegativity decreases
down a group
going across a period, the electronegativity _______
increases
going _____ __ _______, the electronegativity increases
across a period
what 2 factors influence electronegativity and covalent radius
nuclear charge
number of filled electron shells
what does an increase in nuclear charge cause
the atom attracts bonded electrons more strongly
the atom attracts bonded electrons more strongly
increase in nuclear charge
what happens when the number of filled electron shells increases
outer electrons are further from the nucleus
AND
less strongly attracted to the nucleus
outer electrons are further from the nucleus
AND
less strongly attracted to the nucleus
what happens when the number of filled electron shells increases
going down a group, the ionisation energy _________
decreases
going _____ _ ____, the ionisation energy decreases
down a group
going across a period, the ionisation energy _______
increases
going ____ __ _____, the ionisation energy increases
across a period
covalent bond
atoms share pairs of electrons
two positive nuclei held together by their shared attraction for shared pair of electrons
atoms share pairs of electrons
two positive nuclei held together by their shared attraction for shared pair of electrons
covalent bond
polar covalent bonds
formed when the attraction of atoms for the pair of bonding electrons is different
formed when the attraction of atoms for the pair of bonding electrons is different
polar covalent bonds
ionic bonds
the electrostatic attraction between positive and negative ions
the electrostatic attraction between positive and negative ions
ionic bonds
what do ionic compounds form
lattice structures of oppositely charged ions
what compounds forms lattice structures of oppositely charged ions
ionic compounds
bonding continuum
pure covalent bonds —– polar covalent bonds —— ionic bonding
pure covalent bonds —– polar covalent bonds —— ionic bonding
bonding continuum
the larger the difference in electronegativity, the more ______ the bond will be
polar
the larger the difference in _________, the more polar the bond will be
electronegativity
what can a large difference in electronegativity cause to form
ions
non metal to metal bonding
ionic bonding most of the time
is a pure covalent bond polar?
it is non polar
van der Waals forces
intermolecular forces acting between molecules
LDFs exist between ___ molecules and atoms
all
when are LDFs formed
a result of electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms and molecules
a result of electrostatic attraction between temporary dipoles and induced dipoles caused by movement of electrons in atoms and molecules
LDFs
what are LDF strengths related to
the number of electrons within a molecule or atom
when is a molecule described as polar
if it has a permanent dipole
pdp to pdp dipole interactions are ____ than LDFs
stronger
LDFs are ____ than pdp to pdp dipole interactions
weaker
hydrogen bonds are highly ____
polar
hydrogen bonds are _____ than other pdp-pdp interactions
stronger
hydrogen bonds are stronger than other ______ _______
pdp-pdp interactions
hydrogen bonds are ______ than covalent bonds
weaker
hydrogen bonds are weaker than ________ _____
covalent bonds
the MPs and BPs of polar substances are ______ than that of non polar substances with similar number of electrons
higher
the MPs and BPs of ______ substances are higher than that of ______ substances with similar number of electrons
polar, non polar
compare the melting points of polar substances with that of non polar substances with similar no. of electrons
polar has higher MPs and BPs than non polar
why do hydrogen, water and hydrogen fluoride have unexpectedly high MPs and MPs
because they have hydrogen bonds
what effect does hydrogen bonding have on ice
it is an expanded structure that causes ice to have a lower density than water at low temps
it is an expanded structure that causes ice to have a lower density than water at low temps
the effect of hydrogen bonds on ice
hydrogen bonds and MPs
hydrogen bonds cause substances to have higher than expected MPs and BPs
2 features to consider when predicting solubility
- presence of H-O or N-O bonds (hydrogen bonds)
- spatial arrangement of polar covalent bonds (could be a permanent dipole)
what are ionic compounds held together by in the solid state
ionic bonds
LDF are caused by
temporary dipoles
pdp pdp are caused by
permanent dipoles
weakest type of intermolecular forces
LDFs
what are non polar molecules held together by
LDFs
what are polar molecules held together by
pdp pdp interactions or hydrogen bonds
when are ionic compounds formed
when two atoms bond where there is a large difference in electronegativity
what forms when two atoms bond where there is a large difference in electronegativity
ionic compounds
what can covalent compounds can be classed as
polar or non polar
when are polar covalent bonds formed
when atoms with two atoms with different electronegativity values form a covalent bond
what forms when atoms with two atoms with different electronegativity values form a covalent bond
polar covalent bond
in a polar covalent bond, which atom is assigned the negative charge
the atom with the higher electronegativity value
in a polar covalent bond, what is the the atom with the higher electronegativity value assigned
negative charge
in a polar covalent bond, which atom is assigned the positive charge
the atom with the lower electronegativity value
in a polar covalent bond, what is the the atom with the lower electronegativity value assigned
positive charge
what are the attractions between covalent molecules known as
van der Waals
when are non polar covalent bonds formed
when two atoms with the same electronegativity form bonds
what bonds form when two atoms with the same electronegativity form bonds
non polar covalent bonds
what do symmetrical compounds with polar bonds form
non polar molecules
polar molecules are attracted to each other by ____ or ________
pdp pdp or hydrogen bonding
non polar molecules are attracted to each other by _____
LDFs
when do pdp pdp interactions occur
in molecules with a permanent dipole
hydrogen bonds occur between hydrogen and ..
fluorine, oxygen, or nitrogen
stronger intermolecular forces means…
higher MPs and BPs
higher viscosity
____ dissolves _____
like dissolves like
polar substances dissolve in _____ liquids
polar
nonpolar substances dissolve in _____ liquids
non polar
Why is it important to control the rate of reactions
So that they are….
economically viable (they will result in a good yield of products and profits for the company)
AND
safe (the reaction does not progress too quickly potentially causing explosions).
economically viable (they will result in a good yield of products and profits for the company)
AND
safe (the reaction does not progress too quickly potentially causing explosions).
Why is ur important to control rates of reactions
As the reactants are used up, what happens to the reactant rate
It will decrease, the reactions slows down
Average rate equation
Delta quantity
——————
Delta time
Delta quantity
——————
Delta time
Average rate equation
Relative rate equation
1
—
T
1
——
T
Relative rate
Units for reaction rate
S^-1
S^-1
Units for reaction rate
For a reaction to occur, what must happen
The reactants molecules must collide with enough energy
What requires the reactants molecules must collide with enough energy
A chemical reaction
Activation energy, Ea
The minimum kinetic energy required for a reaction to occur
Why must reactant molecules collide with enough energy
To overcome the repulsive forces (caused by outer electrons)
Activated complex
intermediate stage
a high energy, unstable arrangement of atoms
An intermediate stage is reached in which a high energy, unstable arrangement of atoms is formed called the activated complex.
Activated complex
What is given out when the new product bonds are formed
Energy is given out
What happens when new bonds are formed when forming products
(2 points)
Energy is given out
AND
The atoms are rearranged into the product molecules
What must happen for a successful collision to occur
The collision geometry must be right
—> the reactants molecules have to be facing the right way
what happens to reducing agents
they are oxidised
what agents are oxidised
reducing agents
electronegativity of reducing agents
low
what agents have low electronegativities
reducing agents
what agents form positive ions
reducing agents
what ions do reducing agents form
positive ions
where are the strongest reducing agents
top right of page 12
what happens to oxidising agents
they are reduced
what agents are reduced
oxidising agents
what electronegativity do oxidising agents have
high electronegativity
what agents have high electronegativity
oxidising agents
what agents form negative ions
oxidising agents
what ions do oxidising agents form
negative ions
where are the strongest oxidising agents
bottom left of page 12
what are found at the bottom left of page 12
strongest oxidising agents
Symmetry affect on polar bonds
Cancels polarity
