The mole and a bit of nuclear physics ahhhhhhhhhhhhhhhhhhhhh

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1 Angström

10^-10 m

Diameter of an atom:

Diameter of an atom: ≈ 60 – 550 pm (1 pm ≙10-12 m) ≙ 0.60 – 5.50 Å

atomic number (Z)

Thus the number of protons is also called atomic number (Z) (Ordnungszahl, OZ).

If necessary (which is rare in chemistry, because element symbols are unambiguous), it is stated as a subscript to the left of the element symbol:

• Every carbon atom has 6 protons in the nucleus: 6C

• Every oxygen atom has 8 protons in the nucleus: 8O

isotopes. •There are ____ different isotopes for hydrogen. • There are ____ isotopes of helium etc

Atoms of the same kind (same atomic number) but a different number of neutrons are called

Different isotopes have different _____.

Different isotopes have different mass numbers (A). The mass number (Massenzahl) is the number of protons (= Z) and protons (P) present in the respective nucleus: A = Z + #N (The mass of the electrons is so low it can be ignored.) Protons and neutrons are often grouped as nucleons, so: A = number of nucleons.

The atomic mass is stated relative to the ___ isotope ___:

The atomic mass is stated relative to the carbon isotope 12C: if A = 12, and Z(C) = 6, #N = 6. The atomic mass of one atom of 12C is defined to be

The atomic mass of one atom of 12C is defined to be

M(12C):=12.000 000 atomic mass units (a.m.u.), often abbreviated amu or just u

1 u =

1.660 54 ∙ 10-24 g

Mass numbers (obviously) must always be integer. The actual mass of single protons and neutrons in fact are not integer: m(p+) = m(n) =

Mass numbers (obviously) must always be integer. The actual mass of single protons and neutrons in fact are not integer: m(p+) = 1.00728 u m(n) = 1.00866 u

relative atomic mass

Relative atomic mass (symbol: Ar) is defined as the ratio of the average mass of atoms of a chemical element in a given sample

mass defect

Mass defect occurs because the mass of a nucleus is always less than the sum of the masses of its constituent protons and neutrons. This difference arises because some of the mass is converted into binding energy, which holds the nucleus together

calculate 35C theoretical mass and mass defect in gram

with the actual mass of 35,27244

what does octahedrally surrounded mean?

A central atom (often a metal ion) is surrounded by 6 atoms or ligands, arranged at the corners of an octahedron.

• Octahedron = a shape with 8 triangular faces

• The 6 surrounding atoms are positioned symmetrically around the central atom

Ex: a chlorine atom is octahedrally surrounded by 6 sodium ions

ionization energy in the periodic table

the nobel gases have the highest ionization energy

which are the electrons most easily removed?

valence electrons

monatomic atoms and their charge

lattice energy

What would have a higher lattice energy NaCl or RbCl

MgF2 than NaCl?

There is an optimal distance between the cations and anions attracting each other

Energy necassary to pull ions apart in a lattice

NaCl since Na^+ is smaller than Cl^- so higher charge density more lattice energy required to pull apart

MgF2 because F^- is smaller than Cl and Mg²+ has a larger charge

electron affinity

=) energy to force an atom to pick up a electron

He is high because 1s2 so it needs to open a 2s orbital

nobal gases dont want a electron

Nitrogen has three p orbitals with positive spin each (energetically favorable) so adding one is not optimal

thats also why Carbon has such a low electron affinity

what group has the lowest electron affinity

what is a radical?

A radical in chemistry is an atom, molecule, or ion that has at least one unpaired valence electron, making it highly reactive

draw as a dot

two lone electrons diradikal

what is a O=O bond?

explosive

the VESPER model

2 binding partners, 3 binding partners, 4 binding partners + the degrees

5 binding partners + degree

6 binding partners + degree

name in example for binding partners 2-6

sulfur trioxide

for n=3,4 with lone pairs

what geometrical from would sulfur dioxide take? what about ammonia? what about H2O?

angular

trigonal pyramidal

angular

for n=6 with lone pairs

what about SF6 vs IF5. what about XeF4?

octahedral

square pyramidal

square pyramidal

n=5 with lone pairs PCl, ClF3, SF4

VESPER model of H2O

its angular of trigonal planar

CH4, NH3, H2O and HF

we start at tetrahedal

lewis formula nitrite ion

mesomerism

negative charge is equally distributed between two oxygen atoms. NOT a dynamic process the actual nitrite formula is somewhere in the middle but we have no lewis fromula for that

both descriptions are right

which rings are chemically unfavorable?

3 or 4 membered rings

ozone O3

what are sigma bonds and when do they from?

A sigma (σ) bond is the strongest type of covalent bond, formed by the head-on overlap of atomic orbitals along the internuclear axis, with electron density concentrated between the nuclei.

bond lenght

ideal distance between the atoms

the closer they are the lower the energy,

if you push them closer together the repulsion of the nuclei kicks in which raises the energy

hybridisation

In chemistry, orbital hybridisation (or hybridization) is the concept of mixing atomic orbitals to form new hybrid orbitals

how do we make carbon have 4 bindings with hybridisation?

so now C can form 4 bonds with hydrogen because binding pairs are disrubted now sp3 orbitals

sp3 orbitals are now degenerate

hybridisation of N atom and O atom

shape of a single sp3 orbital vs 4 sp3 orbitals

tetrahedrally surrounded

In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron.

homolytic cleavage

The electron pair separate evenly to each part, and as a result both products contain a single electron.

all C-C and C-H bonds are ____

sigma bonds

sp2 hybridsation (C-atom in ground state)

sp2 hybridisation of two carbon atoms. what bonds are happening?

3 sigma bonds between C-C and H-C for the hybridised orbitals

but since the free p orbitals are parallel they can also overlap forming pi-bonds NON hybridised

perpendicular

at a 90 degree angle

diamond vs graphite

diamond: tetrahedically surrounded C-C 154 pm

how long are C-C bonds?C=C and C=-C bonds

single bond 154 pm

douple bond 135 pm

triple bonds 122 pm

sp hybridisation

ethyne C2H2 how many bonds?

1 sigma bond and two pi bonds

name the bonds