University:
Eastern Kentucky University
Course:
CHE 111 | General Chemistry
Academic year:

2022
Views:

481

Pages:

2
Author:

Shyanne Johnson

Unit 2: Molecular and Ionic Compound Structure and Properties Polar bonds: ● 2 different atoms have different electronegativities, so they have different pulls on the shared electrons, so the electrons are not shared equally → polar bond Non-polar bonds: ● Two same atoms will form a nonpolar bond since they have the same pull on shared electrons → electrons are shared equally → nonpolar bond Polar Covalent bonds: ● In a polar covalent bond, the atom that has a greater electronegativity value will have a partial negative charge ● Greater the difference in electronegativity between the 2 atoms bonded → the more polar the bond is Covalent Bonds: ● Two nonmetal atoms bonded ● Not a good conductor ○ Low melting point Ionic Bonds: ● Metal and nonmetal ○ Not a conductor as a solid, but is great conductor when either melted or dissolved in water ○ High melting point ○ Brittle, crystalline Metallic Bonds: ● Metal atoms form a crystal lattice structure with positive nuclei and core electrons, valence electrons are delocalized so they are free to move → good conductor ○ Electron sea model and delocalized electrons ● Alloys: ○ Substitutional: one element takes another's place in the lattice structure ○ Interstitial: one element fits within the spaces between another element in the lattice structure Intramolecular Forces: forces that hold individual molecules together Coulomb's Law: ● Calculates force between 2 charged particles ● Higher charge and smaller radius means stronger force ● Closer the charges are to each other, the stronger the force Potential Energy: ● When bonded atoms separate, PE ↑ because energy must be added to overcome the coulombic attraction between each nucleus and shared e– s Bond Length: ● Increases as you go down a group because atomic radius increases, so the distance between the 2 atoms is greater Bond Energy: ● Decreases down a column because atomic radius increases, the distance between 2 atoms increases, so coulombic attractions are weaker → less energy required to break the bond Bond Order: ● As bond order increases, bond length decreases and bond energy increases ● To calculate, add up total number of bonding pairs and divide by number of bonds Lattice Energy: ● How much energy is required to completely separate a mole of solid ionic compound into its gaseous ions ○ Lattice energy increases when the charge on the ions increases and when the size of the ions decreases Formal charge of atom: (# of valence electrons) - (# of lone electrons) - (# of bonds) ● Formal charges closer to 0 are more stable and show a preferred distribution of e-s Hybridization: ● Occurs when atomic orbitals mix to form “hybrid” orbitals to produce a set of equivalent hybrid orbitals ● Hybridization only depends on lone pairs and bonds on central atom ● Central atom is least electronegative ○ A double bond or triple bond still only counts as one bond ● To determine hybridization of an atom in a molecule: Count each pairing bond(if its double/triple bond, it still counts as one) and nonpairs ● sp hybridization - 1 s and 1 p orbital hybridizes ○ Present in atoms with only 2 electron regions ○ 180°-Bond Angle ● sp2 hybridization - 1 s and 2 p orbitals hybridize ○ Present in atoms with 3 electron regions ○ 120°-Bond Angle ● sp3 hybridization - 1 s and 3 p orbitals hybridize ○ Present in atoms with 4 electron regions ○ 109.5°-Bond Angle