Compounds and Chemical Bonds Part 1 G8 Science Chapter 8.1

Compounds and Mixtures Caffeine Compounds – contain two or more different elements chemically bonded together Mixtures – contain two or more elements or compounds not chemically bonded together C8H10N4O2

Your Turn List 2 compounds. List 2 mixtures. Discuss with your partner(s) why you think these are compounds or mixtures. Share with the class.

Most matter is a mixture of compounds Oxygen molecule Almost everything is a compound, rather than just an element. Almost everything is a mixture of compounds

Chemical Bonds Chemical bonds form when atoms transfer or share electrons. May transfer or share one or more electrons. The atoms are chemically bonded and moves together. What element is this?

Covalent Bonds Covalent bonds are formed when atoms share electrons. Single Bond Double Bond Triple Bond Atoms held together with covalent bonds are called molecules. Covalent bonds are formed between nonmetals and nonmetals. They both have to share! The shared electrons belong to both of them.

Chemical Formulas H2O Water C6H12O6 Glucose C2H6O Alcohol  NaCl Salt Chemical formulas tell many of what kind of atoms are in the molecule. Atomic symbol. Subscript is count of that element. Parenthesis breaks up repeating units. Hint of the structure. Ca3(PO4)2 Calcium phosphate (CH3) 3COH tertiary butyl alcohol Carbonic Acid - H2CO3 Acetic Acid - HC2H3O2 Sodium Hydroxide - NaOH Potassium Hydroxide - KOH

Chemical Structure Chemical structure is important to function. Shows shape and arrangement of atoms. Shows single, double, and triple bonds. Sometimes 3D structures are used. Benzene Acetic acid

Molecular properties depend on Exact formula CHNOPS How many of each? Molecular structure What shape does it take? Glucose Carbonic acid Ethanol

Isomerism Same formula Different structure It is not just the formula that matters.

Your Turn Write down an analogy – two thinks that are made of the same substance but are shaped differently and, therefore, have different uses. Discuss your analogy with your partner(s). Share your analogy with the class.

Activity Practice reading and writing chemical formulas. Handout. Due at end of class. If you get done early, work on homework – do not socialize.