: 1) chemical bonds are the forces that hold atoms and ions together

:1) Chemical bonds are the forces that hold atoms and ions together.

2) Chemical structures or structural formulas are a graphical description of bond length and bond angle.

3) Bonds can bend, stretch and rotate, and the chemical structure of a compound determines it properties.

4) Atoms form bonds so that there is a stable electron configuration.

5) Ionic bonds•Form between oppositely charged ions •Transfer of electrons

•positive ions are called cations, negatively charged ions are called anions

•Form networks of ions, NOT molecules•When melted or dissolved in water ionic compounds conduct electricity

6) Covalent bonds: •One or more pairs of electrons are shared•Usually occur between non-metal atoms•Each line in a structural formula represents the sharing of one pair of electrons

7) Metallic bonds: •Electrons move freely between metal atoms•Outermost energy levels overlap

8) Polyatomic ions: •Groups of covalently bonded atoms that have a charge so they act like an ion•Denoted by parentheses in a formula•Many polyatomic ions contain oxygen •Amount of oxygen is used to determine the name – •more oxygen uses “-ate”, less oxygen uses “-ite”• example: NO3 = nitrate NO2 = nitrite

Determine if the following would have ionic or covalent bonds. Explain your reasoning.

Magnesium Oxide MgO

Strontium Chloride SrCl2

Ozone O2

Methanol CH2OH

Compound Names and Formulas: 1) Ionic compounds are named for their elements•The cation is identified by the element name•The anion is identified by an altered element

name

•Example: NaCl = sodium chloride• Ionic compounds have a charge of zero, so

oxidation numbers must be balanced

Write formulas for the following ionic compounds:

Lithium oxide

Beryllium chloride Titanium (III) nitride

2) Covalent compounds of two elements are named with numerical prefixes. •Example dinitrogen tetroxide N2O4

Organic and Biochemical Compounds1) Organic compounds contain carbon and are covalently bonded.•Carbon atoms form up to FOUR covalent bonds •Compounds of just hydrogen and carbon are hydrocarbons

2) A polymer is a molecule that is a long chain of similar molecules. •Examples: rubber, wood, starch, protein and DNA•Structure determines elasticity

3) Biochemical compounds include carbohydrates, proteins, and DNA