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Key words and key concepts of Chemistry year 1

CH1

1
...
The element with the larger
electronegativity will have the electrons and therefor a negative
oxidation number and the element with a lower electronegativity
will have a positive oxidation number and must cancel out the
negative number unless it is an ion
...
2 Basic ideas about atoms
Alpha radiation (α) – α is 2 protons and 2 neutrons
...

Gamma (γ) – γ is a high-energy electromagnetic wave
...

Shell – Group of electrons in the same energy level
...
These numbers are known as principal quantum numbers
...
Orbitals have different shapes, S orbital has a sphere
shape and the P orbital has a dumbbell shape
...

Ionization Energy (I
...
) – Amount of energy needed to remove 1 mole of
electrons from 1 mole of an element
...

Electron Screening – The inner shells screen the outer electrons, from the
effective nuclear charge, making the attraction less of the outer electron
less
...

A) α can not penetrate paper, highly ionizing and is positively
charged so it is attracted to the far end of a negatively charged
electromagnetic plate, because it is heavy and therefor its velocity
is not easily changed
...
β can not penetrate aluminum, ionizing and is
negatively charged so it is attracted to the closest part of the
positively charged part of the electromagnetic plate because it is
light so its velocity is easily changed
...
γ can not penetrate thick lead, not very ionizing and has no
charge
...

Q) Explain the difference of I
...
energies between He and H, He and Li, Be
and B, N and O, and He and Ne
...
E
...
Li has electron screening and He does not, so Li has
lower I
...
then He
...
N has I higher I
...
then O because O
has electron-to-electron repulsion on the p orbital where as N has
no electron-to-electron repulsion
...
E
...

Q) Explain the patterns of the emission spectrum of hydrogen
...

The bigger the change in energy levels, the bigger the frequency of
EM radiation released
...

Q) Explain how to work out the 1st I
...
of hydrogen
...
Then look at the convergence zone of
the series and find out the difference between n=1 to n=∞ and this
is the wavelength (λ) released
...

f=speed of light (c)/λ
...
E
...
E
...


1
...

A) Isotope mass number (Ix)
Abundance in terms of %
(I1%+I2%+I3%+…I∞%)/100
Q) Form equation for finding moles in solid, liquids and gas
A) moles = mass/MR
moles = consentration x volume/1000
PV=nRT

1
...

Chemical Bond – The positively charged nuclei and negatively charged
electrons are arranged in such a way that the electrostatic forces
outweigh the repulsions
...

Covalent Bond – Each atom gives one electron to form a bond pair in
which the electron spins are opposed
...


Delocalized – Electrons are spread over the whole lattice and not confined
to bonds between atoms
...

Intramolecular – Forces within the molecule
...

Bond Polarity – Share of electrons is not even in a bond between atoms
with different electronegativity, The atom with the higher
electronegativity will be the negative pole (δ-) of the molecule and the
atom with the lower electronegativity will be the positive pole (δ+) of the
molecule
...

Hydrogen Bonding – Hydrogen bonding is dipole-dipole bonding but
hydrogen bonding only occurs when hydrogen is covalently bonded with
F, O and N and the hydrogen dipole-dipole bonds with a F, O and N
...

Q) How are bonds decided
A) All bonding results from electrical attractions and repulsions
between protons and electrons, to bond, attractions must always
outweigh repulsions
...
If there is a large difference in electronegativity it will be
an ionic bond because the share of electrons is uneven
...

Q) Explain the Linus Pauling scale
A) The scale is based on the difference in electronegativity
between two atoms, the larger the difference, the more % ionic
character it has
...
The
F-I bond has a large % ionic character because there is a large
difference in electronegativity
...

Q) Why dose water have such a high boiling point
A) H2O has high boiling point because the hydrogen’s are attached
to high electronegative oxygen
...

Q) Explain how VSEPR theory explain the shapes of molecules, BF3, CH4,
NH3 and H2O
A) BF3 – Boron is attached to 3 Fluorine and no lone pairs
...
CH4 – carbon has 4 hydrogen’s attached to it and all repel

each other so it has bond angle of 110˚ and the shape is
tetrahedral
...
H2O is not linear but has a bond angle of 104˚
because it has two lone pairs repelling the hydrogen’s
...
5 Solid Structures
Q) Explain:
Crystal Coordination Numbers – Number of anions bonded with
cations vise versa, bigger the size difference between the two ions,
bigger the coordination number
...
They both bond in such a way to maximize
electrostatic attraction and minimize repulsion
...
Able to conduct electricity when molten or dissolved because
ions are free to move and conduct electricity
...

Structure and properties of diamond – Each carbon atom is
bonded to four other carbon atoms to form a strong tetrahedral
giant covalent crystal
...
Very high sublime
temperature of 3642˚c because once covalent bonds a broken the
carbon atoms have the energy well above there boiling point and
turns to gas
...

Structure and properties of Graphite – Each carbon atom is
covalently bonded to three other carbon atoms to form one atom
layer hexagon structure with delocalized electrons in the layer
...
High sublime point because of high energy
needed to break covalent bonds
...

Cannot conduct electricity because it has no delocalized electrons
...

Structure and properties of Ice – Hydrogen bonds between water
molecules hold the water molecules in a tetrahedral structure
...
The sea of electrons surrounds
the closely packed cations and binds them together through the
attraction between opposite charges
...
Down the group, the strength of
metallic bonding decrease because the size of the cation increases,
therefor the density of electron sea decreases
...
6 The Periodic Table
Q) Explain trends in periodic table and therefor the behavior of elements
in terms of:
A) 1st I
...
E increases across the table because of increase in
effective nuclear charge across the table, but little or no increase in
electron shielding and distance between 1st electron and nucleus
...
E
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E becomes so high that electron sharing occurs
and the electronegativity in group 6 and 7 is so high that they form
anions
...
E are generally metals because they
easily give up electrons to the electron sea
...
E are generally non-metals because they share electrons
...

A) Melting temperature (MT) – MT genuinely decrease down the Sblock elements because of decrease in metallic bonding forces
...
MT across the table
increase from group 1 to group 4 because strength of metallic
bonding increases from group 1 to 3
...

Redox reaction – Reaction involving one species losing electrons to
another species
...

Q) Explain S-block elements:
A) Reactions with:
Group 1 and 2 reacts with Oxygen
Group 1 + Oxygen ⇒ Group 1 Oxide
2Na + O2 ⇒ Na2O
Group 2 + Oxygen ⇒ Group 2 Oxide
Ca + ½O2 ⇒ CaO
Group 1 and 2 reacts with Water
Group 1 + Water ⇒ Group 1 Hydroxide + Hydrogen
2Na + 2H2O ⇒ 2NaOH + H2
Group 2 + Water ⇒ Group 2 Hydroxide + Hydrogen
Ca + 2H2O ⇒ Ca(OH)2 + H2
Group 1 and 2 reacts with Acid
Group 1 + Acid ⇒ Salt + Hydrogen
2Na + 2HCl ⇒ 2NaCl + H2
Group 2 + Acid ⇒ Salt + Hydrogen
Ca + 2HCl ⇒ CaCl2 + H2
Group 1 and 2 Oxides reacts with Acid
Group 1 Oxide + Acid ⇒ Salt + Water
Na2O + 2HCl ⇒ 2NaCl + H2O
Group 2 Oxide + Acid ⇒ Salt + Water
CaO + 2HCl ⇒ CaCl2 + H2O




A) Trends with:
Solubility – Group 1 salts are all soluble
...
Group 2 sulfates solubility decreases
down the group
...
All S-block nitrates are soluble
...

Flame Colours

Q) Explain Halogen:
A) Reactions with:
Silver Nitrate – Silver cations and halide anions react to
form a precipitate
...

Metals – Halogens react with most metals to form halides
...

Oxidising Power – Oxidising power decreases down the
group because electronegativity decreases
...
Appears to have only beneficial effects below 1ppm
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Helps reduce tooth decay
and osteoporosis
...

There has being opposition on fluoridation on public water on
ethical grounds
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7 Simple equilibria and acid-base reactions
Reversible Reaction – Reaction that can go in either direction depending
on conditions
...

Position of Equilibrium – Proportion of products to reactants in an
equilibrium mixture
...

Find Kc – Kc is the equilibrium constant; it is the ratio of concentrations of
the 2 sides of the reaction
...

Acid – Is a proton donor
...

Alkali – Base that is able to dissolve in water, the ion common to all alkalis
is the OH- ion
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pH scale – pH = -log[H+]










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