Observations to be Made about a Chemical reaction
-macroscopic level(from last course.)
Interpretation of Observations
Classification of the elements
-First elements Cl, Br, I (similar grouping in the modern)
-S, Se, Te
-Classifying element in groups of three that have similar properties and reactions
-Ca, Sr, Ba
-Li, Na, K
-Fe, Co, Ni (did not have similar atomic masses in comparison to the others)
-Doberiener's Triads (1829) - organized groups of three
-Newland's Octaves - groups of eight
H, LI, Be B, C, N, O
F, Na, Mg, Al, Si, P, S
Inert gasses are not there; yet to be found
Cl, K, Ca, Cr, Ti, Mn, Fe
Co, Cu, Zn, Y, In, As, Se (no longer viable)
-Put them in order of increasing atomic mass and set them in groups of 8
Put in order of increasing atomic mass.
And where the mass did not fit he left spaces
Fe, Ni, <=> Co, Cu (transitional elements, it is the number of protons and electron that
determines the properties of an element thus it has to put into order of increasing atomic
Te and I it was in the reverse order.
K (lights one is most abundant) (39.100)
Isotopic abundances: Ar (the heaviest one is the most abundant) (39.948 avg.)
Periodic Trends in the Properties of Elements
Normal valence (combining power of the element)
-Orbitals= construct of the human mind and not the best option
Ionization Energies (kJ/mol)
2nd row in the table the ionization increases as going across the periodic table.
Similar trend in the 3rd row
Suggest that the electron in the atoms of the 2nd row are all similar distances away from
the nucleus and moving from element to the next and mor positive charges are added it will
take more energy to remove the electron.
If the electrons are further away from the nucleus it means that the energy is weak. (Ne)
Which means you need to start in a new row
-B, Al, O, S are green because they do not follow the increase trend. Between Be and B
and N and O there is a decrease but they are small decreases so no need to start a new row.
Similarly in Mg and Al
Successive Ionization Energies
-removing the electrons and how much energy is takes
-takes more energy to remove the inner electrons in comparison to the outer electron since the
energy is weak
First Ionization Energies of Transition Metals
-Sc, Ti : this row is increasing but not by much, the transitional elements are much similar to
each other than the other elements.
Atomic and Molecular structure
Monday, January 5, 2015
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each other than the other elements.
-Elements in the fourth row that are not metals there is a tendency to increase, but the 2nd and
third element which is a general trend
The ionization energies-transitional elements are rather flat.
-as you go across the row the atoms get smaller giving you smaller atoms
-diagonal relationship there are two atoms are similar in size
Comparison of the two Diagrams. Where there are peak element that is the largest(in size) and
where you have the smallest ionization energies.
At room temperature the metals are all solids except for Mercury
All are conductors
As you go across metals to semimetals to non-metals
Down Non-metals to semi metals to metals
-group 14 starts with C and Si which are not metals and moving downward there are metals
-Hydride of NaH reacts with water produces
-NaH is a base in aqueous solution
-Combination of HCl with H2O, HCl is an acid
Binary Oxides and 3rd Row Elements
-Metals are basic and non-metals are acidic
-MgOH is not soluble due to the charge +2 and -2 (referring to Coulombs law)
On this base we can call AlOH an acid which can be known as amphoteric(which can be
both acid a base
-AlOH can react in aqueous base to consume OH to produce Al(OH)4
-SiO a strong acid
-SO3first proton is strong acid then the second proton is weak acid
-Across a group Blue to the left weak acid to the right
-Down a group N2O5strong acid to weaker aid then to a weak base to a strong base
What are the components of the atom?
-Faraday: change in mass
-Crookes: characterized the rays from cathode ray tube where there were particles
which are NOW KNOWN TO BE ELECTRONS (Mendeleev, Newland and Dob
could not figure it out to order in atomic number due to this)
-Thompson: charge to mass ratio of the electron
Individuals to give us the components of the elements:
READ CHAPTER 2 more info on them
What experiments bear upon models of how the particles of the atoms are arranged?
Few of the alpha particles went right through the foil, some didn't pass through and
others hit the foil and bounced back
Something heavy in it which is now known as the nucleus
Alpha particle is the helium nucleus
If it hits something heavy in the middle it will bounce back at some angle
The protons were in the middle around them was empty space and around that was an
orbital where the electrons are
Charge does not play a charge alpha particles are energetic so they can overcome any
positive charge to positive charge.
1.Rutherford: The source was uranium and the radioactive form of uranium gives off a
beam of alpha particles
when we put this in water, oxygen has 6 electrons in its valence shell. it reacts with the H20, and clearly the extra
electrons on this oxide anion will be attracted to the most positive part of the water molecule (the hydrogen) if
we made a bond then there would be two bonds(between the that first hydrogen and oxygen) but we can’t have
that so we need to break that bond (the one between first H and O) the result gives us this new OH bond (so now
we have 2 hydroxide anions) conventionally when writing this we use curved arrows to show the movement of a
pair of electrons , so here we have the pair of electrons to make a new OH bond and this pair is going to that
hydrogen normally has one electron, but hydride ion has an extra one so it has 2 electrons. this now will react
with water, and again the negative hydride ion with its pair of electrons will be attracted to the positive hydrogen
of the water molecule so that pair of electrons goes there, so in order to ensure this hydrogen only has one bond
we have to break that OH bond, the result in this case produces a hydrogen molecule and a hydroxide anion.
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