Chapter 11, Lesson 2 - Compounds, Chemical Formulas, and Covalent Bonds
Results in a polar molecule
When a covalent bond forms between elements with very different atomic numbers, the electrons from the lower atomic number element are pulled closer to the element with the higher atomic number. What does this form?
Covalent Bond
a chemical bond formed when two atoms share one or more pairs of valence electrons.
Chemical Bond
a force that holds atoms together in a compound
molecule
a group of atoms held together by covalent bonding that acts as an independent unit (eg. C6H12O6, H2O, H2, N3, O2)
Chemical Formula
a group of element symbols and numbers (written as subscripts) that represents the number of elements that make up a compound. This does not show bonding, 3-D structure, or shared electrons. (eg. CO2)
Electron Dot Diagram Molecule
a model of a covalent compound with a group of element symbols showing the sharing of valence electrons in a covalent compound. This does not give a 3-D representation of the molecule.
Polar molecules
a molecule that has a partial positive end and a partial negative end because of unequal sharing of electrons. (eg. water)
compound
a substance containing atoms of two or more different elements that are chemically bonded together. (eg. H2O, but NOT H2)
Nonpolar Molecule
the type of molecule formed when the electrons in a covalent compound are equally shared. (eg. H2)
like dissolves like
this expression means that a polar solvent will dissolve a polar substance, but not a nonpolar substance. Conversely, it means a nonpolar solvent will dissolve a nonpolar substance, but not a polar substance.
single covalent bond
when just one pair of electrons is shared between two atoms, this type of bond is formed. (eg. water)
triple covalent bond
when three pairs of electrons are shared by two atoms, this type of bond is formed between them. (eg. nitrogen gas)
double covalent bond
when two pairs of electrons are shared by two atoms, this type of bond is formed between them. (eg. carbon dioxide)
