Chem - Ch. 4 Chemical Bonding

ionic bond

bond that results from electrostatic attraction of cation to an anion

covalent bond

bond where 2 atoms share 1 or more mores of electrons

metallic bonds

atoms in metallic solids are held together by a “sea” of mobile electrons that flows freely among all atoms in a piece of metal

polar covalent bond

acts as a tiny dipole, with a slightly positive pole and slightly negative pole

bond polarity

be explained using the concept of electronegativity

Binary Molecular Compounds

• Two nonmetals

1. The first word is the name of the first element in the formula.

2. For the second word, change the ending of the name of the second element to -ide.

3. Use prefixes to indicate number of each atom.

Binary Ionic Compounds of Main Group Elements

• two-word names.

1. First word is name of cation

2. Second word is name of anion with –ide ending

Binary Ionic Compounds of Transition Metals

• Roman numeral system

• Roman numeral indicates the charge of the cation.

examples: Cu2O: copper(I) oxide, CuO: copper(II) oxide

• Historical names

• Ion with lower charge ends in –ous

• Ion with higher charge ends in –ic

examples: Cu2O: cuprous oxide, CuO: cupric oxide

Polyatomic Ions

consists of two or more atoms joined together by covalent bonds

oxoanion

A polyatomic ion containing at least one nonoxygen central atom bonded to one or more oxygen atoms

Binary Acids

An acid is a compound that releases hydrogen ions (H+) when dissolved in water

naming binary acids:

1. Add the prefix hydro- to the name of the second element.

2. Replace the last syllable in the second element with –ic followed by acid.

Naming Oxoacids:

1. If ending of oxoanion name is –ate, the name of the oxoacid ends with –ic acid.

2. If ending of oxoanion name is –ite, the name of the oxoacid ends with –ous acid.

Five Steps for Drawing Lewis Structures

1. Determine the total number of valence electrons.

2. Arrange symbols of elements to show how atoms are bonded together and connect them with single bonds.

3. Complete the octet of atoms (except hydrogen) bonded to a central atom by adding lone pairs of electrons.

4. Compare number of valence electrons in the Lewis structure with the number determined in step 1.

5. Complete the octet on the central atom.

Resonance

Resonance is present when two or more Lewis structures can be drawn with the same arrangement of atoms but different arrangements of bonding electrons and lone pairs.

Formal Charge

The structure that best represents the actual bonding pattern in a molecule can be determined by calculating the formal charges on each atom.

Which elements form electron-deficient molecules when forming covalent bonds?

Be, B, and Al

Which elements can have more than an octet of valence electrons?

non-metals period 3 and bellow