Kugelwolkenmodell (KWM) and Molecular Structure

Molecular Formation, EP Dash Formula, and 3D Molecular Structure

• The Kugelwolkenmodell (KWM) is a useful working model for describing chemical bonds between atoms.

Advantages and Limitations of the KWM

• The KWM can explain certain aspects of molecular bonding.
• There are situations and examples that the KWM cannot explain.

Rules of Applying KWM

• The rules for applying the KWM should be known and applicable to chemical formulas.

Determining Atom Bonding

• Using the KWM, the number of bonds an atom can form (valence) can be quickly and reliably determined.

Exercises and Terminology

• Understandings of exercises and terminology should be precise and concise.

Drawing Molecules with Single, Double, or Triple Bonds

• Small molecules with single, double, or triple bonds between atoms can be drawn using the KWM.

Drawing Molecules with KWM representation

• Small molecules can be drawn in the KWM representation.

Transitioning between KWM Application and Dash Notation

• The step from the KWM application to dash notation is understandable.

Drawing Dash Formulas (Lewis Formulas)

• Dash formulas (Lewis formulas) can be drawn for molecules given their sum formula.

Tetrahedral Angle

• With the tetrahedral angle known, its size can be identified (without deriving the formula).

Significance of Tetrahedra

• The significance of tetrahedra in considering molecular geometries is understood alongside typical bond angles (90°, ca. 120°, exactly 120°, 180°, ca. 110°, 109.47°).

Water and Ammonia Molecules

• Full details of water and ammonia molecules are known.

Spatial Arrangement of Small Molecules

• The spatial arrangement of small molecules can be recognized using the KWM and dash formulas.
• It can be expressed in appropriate dash formula notation, considering angles.

Formal Charges

• Formal charges are understandable and can be determined in particles like molecules or polyatomic ions.

Ozone Molecule

• All details of the specific ozone molecule are readily known.

Homologous Series of Alkanes

• The homologous series of alkanes with CnH2n+2 is known, where CnH2n+2 represents alkanes consisting of carbon (C) and hydrogen (H) atoms.
• Nomenclature (from CH4 to C10H40) using Greek or Latin numerals with the suffix -an is familiar.

Combustion of Hydrocarbons

• Combustion is identified and the correct combustion equation can be set up for hydrocarbons (given with sum or Lewis formula).

Combustion Products

• Combustion products CO2 and H2O are stable, as those molecules have more polar EP bonds than the starting materials.
• Products are energy-stabilized molecules as alkane oxidation products (all atoms linked with O).

Detecting Combustion Products

• Products of combustion can be detected.

Exams

• Exam questions require applying known information rather than memorization.

Models for Weakly Bound Electrons to Atomic Nuclei

• Electrons are not all bound equally strongly to the nucleus.
• The nucleus comprises neutral neutrons (n°) and positive protons (p⁺).
• Number of Protons: Also called the order number or the nuclear charge number, uniquely identifies an element.
• Thomson's Atomic Model describes atoms as structures with elementary particles like raisins in a cake.

Chemical Focus on Valence Electrons

• Chemistry studies electrons in the electron shells.
• Rosinenkuchen-Modell (raisin cake model): A theory by Thomson that does not discuss the arrangement of electrons in the shell.
• The heavier particles p⁺ and n° concentrate in the nucleus, implying the lighter electrons must be located outside, in a shell around the nucleus.

Electron Movement

• It was believed electrons need to be moving to prevent being drawn into the nucleus by its attraction. The model thus included the electron's orbit.

Limitations of Early Electron Models

• Original ionization experiments consisted on removing single electrons from neutral atoms, at the cost of ionization energy. Niels Bohr determined that the electron shell has groups of electrons. Those furthest from the nucleus are relatively easily to remove are arranged in shells.

Coulomb's Law and Electron Shells

• The farther an individual electron is from a charged nucleus, the weaker their attraction.
• Electrons are arranged in shells.
• Valence electrons are the ones on the outer shell.
• The shell model theorizes using shells. The more shells, the larger the atom!
• The shells from the inside to the outside are marked wih the letters, K, L, M, ...

Simplified Electron Configuration

• Simplified electron configuration determines the number of electrons on each shell.
• According to the PSE, the atom with 18 pts in the nucleus is an argon atom.
• This element has 18 electrons in its neutral state, distributed among the three shells (using the shell model).
• With its 8 electrons on the outer shell (or 8 VE), the Ar atom is very stable as a noble gas atom.

Noble Gas Configuration

• Simplified form of atom indicates the number of electrons in each shell. An atom with 18 protons in its nucleus is an argon atom. It has 18 electrons in the neutral state, arranged on three shells, with 8 VE in the outer shell making it stable.

Neutral Atom Configuration

• The neutral Ar atom configuration is given by 1s2 2s2 2p6. It has shells 1 and 2.
• The Hochschul theory refers to the principal quantum numerals 1 and 2. S and P electron stand for energy levels electrons exhibit (w/ associated secondary quantum numerals). The numbers 2, 2, and 6 define the number of associated 1s, 2s, or 2p electrons.
• In 2s2 2p6, the second outer shell shows that 2 + 6 = 8 outer electrons. The number of a main group element's VE is defined by PSE (in Romval above. A Nobel Gas will never connect it to any other Atom, since it already has the maximium number of electrons in its valence shell, namely 8. Elements that are at less stable, namely with fewer than 8 VE, will connect w/ others to create molecules.

Atom Number of Shells

• The Ne atom (OZ = 10) from the 2nd PSE period is also stable from its 8 VE. From this, we know it has 2 shells.
• The Pauli rule is a rule and not a theory (Moleküle S. 2). Ne-Atom features a nucleus w/ an inner shell (atom rumpf) and a valence shell w/ 8 VE (4 EP).

Number of Atom Shells

• The number of shells for these atoms: H, C, S, Xe, K, Cs, Ag, Br, Au, Pb.

Valence Electrons

• The number of VE in the following atoms: K, Al, Se, He, Ca, N, P, CI, F, B.

Electron Orbitals

• Electrons reside in Electron Clouds, a concept used by chemists.
• S Electrons have a spherical orbital. Each electron can have maxiumum 2 electrons (EP!). Every H-Atom has a 1s-e (symbolized w/ the arrow).

P Electrons

• P electrons can also be visualized in space. The three hantel-like orbitals can be marked px, py, and pz. Orbitals are aligned with the coordinate axis.
• When each P-Orbital takes maximum 2 electrons, the sum comes out to 6. This represents the number of filled <>. The sum 8 is obtained w/ those two s Electrons. This is the number accounted in the Edelgasregel (2 VE + 6 VE = 8 VE). Electrons may also be referenced as oktett Regel. An Electronoktet stabilizes an Atom!

simplified Representation of s and p Orbitals

• There is only the talk about s and p electrons. There is a simplified Representation of s und p Orbitals. Maximum 8 VE are taken into account. All Electron Clouds are simplified by displaying them as sphere. These spheres are periodically ordered w/ Atomrumpf. The depicted Atom originates from which Group in the PSE?

Simplifying the Orbital Model

• Focuses on valence electrons (s- and p-electrons)
• Considers atom core for background only
• Simplifies electron clouds into spherical shapes, like s-orbitals
• Refers to "Kugelwolken-Modell der Elektronen" (KWM)
• Helps understand reaction behavior of main group elements

KWM Application Rules

• Depicts only valence shell and atom core
• Assumes spherical electron clouds
• Arranges valence electron clouds around the atom core
• Shows a maximum of eight valence electrons
• Distributes these eight electrons in maximum four electron clouds

Pauli Principle and Hund's Rule

• Each electron cloud holds maximum two electrons
• These two electrons are different in the spin property.
• The Hund'schen Prinzips states that a Kugelvolke cant take in a 2nd Elektron before all other Kugelvolken in the same shell have one each.

Minimizing Repulsion

• Kugelwolken are arranged to decrease repulsion.
• Electron clouds maximize the distance apart.

Atoms in KWM Representation

• Electrons pair in the same KWM cloud, indicated by a line.
• The cloud is then filled completely.
• Electrons of isolated neutral atoms pair up.
• Noble gasses are the only ones that fulfill this requirement.
• All other PSE Atoms come with partually full.

Forming Electron Pairs

• Singular electrons connect from separate atoms to form electron pairs. Overlapping KWMs form and become fully occupied. This KW in the center will connect the separate Nuclei. Resulting EP will connect the Atoms. This chemical connection will be marked as Elektronenpaar Binding. Synonymes are Atombindung und kovalente Bindung.

Atom Association

• EP bindings combined with one another will form Atom Associations, termed Moleküle (Molecules). This applies to independent elements combining nonmetal atoms: it is the NonMetal Atoms in the outer Layer that have the ability to combine w/ others.

NonMetal Atoms

• They have few VE! NonMetal-Atoms in turn feature between 4 and 7 VE to be combined!. Formation of a Cl2-, O2-, and N2 are the result.

Molecular Representation

• Atoms’ simplified representation as KWM or in Kimball Modell or, Fluor-Moleküls

Double Bonding

• O2-Molekül is illustrated as a double bond.

Triple Bonding

• N2-Molekül is illustrated as a triple bond.

EP Bonding Model

• Each binding EP will connect the Atoms through an Elektronpaar-Binding. For each Atom count the number of binding plus not-binding.
• Sum out at the number 4 (equals noble gas status in the Valence Shell. EP Binding Model implies connections with other elements: If not, then you will find a singular Electron.

Simplified Sumarization

• Any 2 singular charged Electron Clouds elements will combine to form an Electronenwolke.

Binding and Value

• A binding Elektronenpaar (Electronpair) will have the effect of chemical binding.
• The binding Electronpaar features w/ Atoms Rumpfen.
• Singular charged Elektronenwolken or singular Elektron will allow for various connection options. The term Wertigkeit applies to an atom's Binding in Molecule's.

Molecule Formation from Nonmetals

• Need to first consider VE/EPs and unpaired electrons on atoms for molecules.
• Bonding and nonbonding pairs must be considered.
• EP Notation forms, which become LEWIS Notation.
• Distinguished through precise illustration through line/EP configuration.

EP in LEWIS Formation

• Need to sketch LEWIS formation: any element has a EP configured (line).

Edelgasregel: Apply for singular Atoms in Molekueln. Need to fill the count: free EPs are not-binding.

• Consider number Elements and configuration.

Lewis Formula vs Sum Formula

• Lewis formulas illustrate structure and relation rather than quantities.

Kugelwolken Surroundings

• Four KugelWolken surround the nucleus of an atom and push each other off to form a tetrahedral structure on the C-Atomrumpf.
• KWM-Tetraeder differentiates a molecule. If 4 similar Atom form the tetraedeisch Atomrumpf, mark it with the tetrahedron
• Tetrahedral molecules are CH4-Molekül (methan). Implies the place of any 4 H Atoms, or any 4 CI-Atoms surrounding a C Atom. Tetraeder imlies the surrounding nature of the H- bzw. Cl- Elements.
• The Atomrumpf C or SI w/ Tetraederkanten represents the same 4 Atoms - the angle between equal H-C-H of Cl-C-CL will result in a geometric binding.

Geometric and Formulae

• Consider the geometry of binding:H-C-H oder Cl-C-Cl in Tetraederwinkel.
• In the example of the depiction of the grosse Würfel and various kleine Würfel: depict the Tetrahedron angle.

Geometric Center

• The Atom will be inside the tetraheder. To remember: 109.47 Winkel.
• Side Kante from a kleinen Würfel remains uncounted, since Tetraederwinkel is not in use. Side Kante = 1/2 Seite a and Flachendiagonale + 2-2 with a.

Types of Molecular Representations

• The different types of molecular demonstrations show
• vereinfachte Lewis-Formel in comparison to the Stab-Darstellung or the Dreiding-Modell.

Lewis-Formel and Spatial Structure

• Many characteristics of molecules are linked to spatial structure. EPA models are used to to determine the geomertry.
• The negative electron wolken have connections (Ep) connections and must be symetrically alinged resulting in a aussen Atomrumpf.
• H2-C=CH2 or Ethen can be formed in different forms. One bond will need H-Atom binding, and then two binding EP (centre), resulting in to Doppelbindung.
• The non-visual Atomrumpf of the C-Atom from H2C sits in the centre. H2K=CH2 joins 2 tetraeder. Strichformel describes Atom (C- and H)
• Any Atom with one DB features in a location, so you get near to 120 angles

Linerare Moleküle

• This is shown by the Molekül CS2.

Atomrumpt

• All Atompfe is Tetraedrisch.

Electronpairs

• Implies the # of VE all divide through 2
• EP so that the Atomrumpfe from the Kraften and maximum Abstoßen (give korekre binding).

Binding Angles

• The Edelgasregel features: # KW = # Striche.
• Exact 109.47 bindung winkel: The Kohlenstoff-Atom features through EP with Wasserstoff-Atomen. This forms Vier C-H-Richtungen through KW-Tetraeder. The H-Atome also form an Außenseite, making it Zentrum-Ecken.

Ammonia Molekul

• NH3 implies that the Element features 4 Elektronenwolken to form KW Tetraeder. Stickstof-Atom has 3 bindende Elektronenpaaren/EP and with a bindungslos Elektronenpaar.
• Aus the LEWIS-Formel from WasserMolekül H20 is shown by Stickstoff-Atom and includes 4 Elektronenpaaren KW. Not all W-Atome connect H-Atome. W Tetraeder sorgt therefore 4 H nicht verbinde

Besonderheiten

• In Elementen kann Atom in Elektronpaaren zuordnen. B-Atom does connect 3 VF w/ binding formation. the Elemente are auf einer ebene. Winkel ist exakt zu messen bei 120.

180 Degrees Bindungswikel

• Beim Methan stimmt der with Tetrahedronkwinkel von 109 ist im kleineren Molekül ist die Einengung da kleinere.

Mehrfachbinding Angles at C-Atomen

• EP are defined and repelled in Bindungswinkel.

Single Connection

• Tetraedrekwinkel between 109 -109.

Twinbindungs

• Bindung Winkel are smaller 120.

Doppelbindung

• Am Atom with 180 winkel.

Dreifachbinding

• Angular Winkel are 180. Atomen are in linear formation.

Raumlichestruktur

• C02 is with linear anordnung - all atom from c with EP verbunden.

Molecule Structure and Structure Formula

EPA Structures

Structures: with EP Formation

EPA: Predict Structures with Known Formulas

Formula Demonstration

Bondinngs in Kohlenstoffen