Molecular shape

• Electron: is a negatively charged subatomic particle

  • Electron shell: orbit/rings around a nucleus, represented by n = a number

    • Subshell: space where electrons are, giving info about where they are and what they are doing. There is an s, p, d, and f orbital

      • s holds 2 electrons (holds 1 atomic orbital)

      • p holds 6 electrons (holds 3 atomic orbitals)

      • d holds 8 electrons (holds 4 atomic orbitals)

      • f holds 14 electrons (holds 7 atomic orbitals)

      • atomic orbitals hold 2 electrons

        

• Covalent bond: is when two atoms share an electron in order to fill its octect

• Ionic bond: is when one atom transfer electrons to another, creating cation and anion

  • Cation: when an atom loses an electron, it forms a positive cation (pawsitive!)

  • Anion: when an atom gains an electron, it forms a negative anion

    • Cations and anions are attracted to each other (opposite charges)

• Lewis Structure/Lewis Dot Structure: is a simplified drawing of how the valence electrons of an element bond with the other valence electrons of another element, and if there are any lone pairs

  • Central atom: is typically the atom in the middle, forming the most bonds

• Electrons are negatively charged, and negatives repel. So, when forming molecules, the electrons make a shape to maximize the distance between themself and other electrons.

  • Electron domains/Steric number: region where electrons are most likely to be found, bonding and non bonding. Note: a bond, double bond, triple bond, or lone pair, all count as only 1 electron domain

• AXE method: a way to count electron domains and predict what the shape of the molecule will be. A is the central atom, with a subscript of 1. X is the amount of bonds the central atom is forming to other atoms. E is the amount of lone pairs of electrons on the central element. The steric number is the sum of X and E.

  • Different shapes form based on steric number and the amount of lone pairs

  • Typically molecules will have 2-6 electron domains, flashcards here: https://knowt.com/flashcards/5797fac8-0f6e-493f-91eb-3ef80e2a443b

    • 2 electron domains: linear

    • 3 domain electron domains: trigonal planar (AX3), bent (AX2E1)

    • 4 electron domains: tetrahedral (AX4), trigonal pyramidal (AX3E), bent (AX2E2)

    • 5 electron domains: trigonal bipyramidal (AX5), seesaw (AX4E), T-shaped (AX3E2), linear (AX2E4)

    • 6 electron domains: octahedral (AX6), square pyramidal (AX5E), square planar (AX4E2)

Hybridization

• Hybridization: low energy state is preferably for elements, so you can hybridize atomic orbitals (s,p,d,f) into hybrid orbitals (like sp) which is a new shape!

  • To find hybridization: consider number of electron domains, if it is 2 then the hybridization is sp, if it is 3 then the hybridization is sp2, if it is 4 then it is sp3, if it 5 then it is sp3d, if it is 6 then it is sp3d2

    • Ex: a hybridized is a new shape, so CH4 has 4 sp3

Polarity

• Electronegativity: measure of how strong an element is pulling electrons towards itself. Smaller elements tend to be more electronegative.

• Polarity: when differences of electronegativities happen, there is an uneven distribution of electron density. in essence, the electrons aren’t being evenly shared

  • Polar covalent: when 2 elements bond and share an electron, but one pulls harder because of the higher electronegativity

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  • Dipole moment: measures separation of positive and negative charge within a molecule

  • Polar bonds

  • Polar molecules

• Non-polar covalent: when two atoms share atoms equally, so there is no dipole moment. this occurs between bonds of the same element, or when the electronegative difference is small (>0.4

Oxidation, Nomenclature, Metallic/Ionic/Covalent Bonds

Gas Laws