ie. molecular compounds 1.Covalent bonds form between similar or identical atoms (most often 2 nonmetals) 2. join nonmetallic atoms together to form molecules. The 2 nuclei attracted the same shared electrons - orbitals from the 2 atoms overlap.
covalent bond basic structure unit
molecular compound form
1. Molecular compounds may be solid (sugar), liquid (water), or gas (oxygen). 2. If soluble in water, usually produces a no conducting solution. Exception : acids
covalent properties (4)
1. Low melting point 2. Low boiling point 3. Does not conduct electricity 4. Can form large macromolecules in solid form, called covalent networks (VERY high melting points)
1. Ionic bonds form between atoms of dissimilar elements (metal&nonmetal) 2. Electrons transfer is involved 3. Do not contain discrete molecules - alternating (+)&(-) ions.
ionic compound form
1. solid at room temperature 2. If soluble in water, forms a solution that conducts electricity due to the presence of ions (charged particles) in the solution
the valence electrons are shared
the pairs of valence electrons are not shared
The number of covalent bonds formed by a nonmetallic element is directly correlated with the number of electrons it must share in order to obtain an octet of electrons. ex. Ex: Fluorine - F - 7 valence electrons (VIIA). It needs only one electron to achieve the octet.
each atom contributes one electron
each atom contributes two electrons
each atom contributes three electrons
coordinate covalent bonds
both electrons shared comes from one of the two atoms Note: Atoms participating in coordinate covalent bonds generally do not form their normal number of covalent bonds.