chapter 8 & 9 Flashcards
What is a nonpolar covalent bond?
A nonpolar covalent bond is a type of chemical bond that is formed when electrons are shared equally between two atoms.
What is a polar covalent bond?
A polar covalent bond is a type of chemical bond that is formed when electrons are shared unequally between two atoms.
What is a covalent compound?
Covalent compounds are made of two non-metal atoms that share electrons in the valence orbitals.
What are 3 properties of covalent compounds?
Covalent compounds are mostly solids that are not soluble in water and not conductors of electricity. (Think of oil, wax or crayons).
1. Low melting points if solid. Otherwise liquid or gas are often flammable.
2. Does not dissolve in water (insoluble).
3. Poor conductors of electricity.
Explain the “Octet Rule”
Elements will typically fill their valence orbital with 8 electrons maximum. *Stable compounds form when atoms achieve noble-gas electron configurations
What are 3 steps in writing Lewis Dot Structures?
1.Count the number of valence electrons, place the least electronegative element in the middle of structure.
2.Draw LINES to represent bonding electron pairs to connect the atoms with bonds.
3.Draw DOTS to represent non-bonding or lone electron pairs and fill each element with 8 electrons maximum.
What is VSEPR Theory? Explain how VSEPR theory is used to predict molecular geometry?
Valence Shell Electron Pair Repulsion model is useful to help predict the molecular geometry and overall shape that the molecule will exist in 3-dimensional space. Because Electrons Repel - electrons will position themselves as far apart as possible in 3-dimensional space to minimize the repulsion between electron pairs.
What is an expanded octet?
Expanded octet occurs when molecules share more than 8 electrons in their valence shell.
Give 2 examples of molecules that do not follow the octet rule:
XeF4, PCI5, SF6
What is a dipole? Which molecules have a dipole - Nonpolar covalent or polar covalent?
dipole δ = separation of positive and negative charges; polar covalent bonds have a dipole
How does electronegativity help determine the charge distribution in a polar bond?
the polarity of a bond depends on the difference between the electronegativity values of the atoms forming the bond, the dipole
Are intermolecular forces of attraction the same as ionic or covalent bonds? Explain.
- Intermolecular Forces of Attraction are attractive forces that occur BETWEEN molecules
- Intramolecular Bonding attractive forces that occur between atoms WITHIN a molecule; these are true chemical bonds, of two types:
1. ionic bond = electrostatic attraction between metal cation and nonmetal anion
2. covalent bond = electron pair sharing between nonmetal and nonmetal
What are the Intermolecular Forces of Attraction?
Van der Waals Forces, London Dispersion Forces, dipole-dipole interactions, hydrogen bonds
Describe 3 differences in properties of Ionic and Covalent Bonds and Compounds
Ionic Bond - electrostatic attraction between metal and nonmetal
ionic compounds have high melting and boiling points
ionic compounds dissolve in water, do not dissolve in oil
Covalent Bond - sharing of electron pairs between nonmetal and nonmetal
covalent compounds have low melting and boiling points
covalent compounds do NOT dissolve in water, dissolve in oil
Van der Waals Forces
weak, temporary intermolecular forces of attraction between molecules; assume van der Waals forces are present between all molecules
