Chapter 4: Formation of Compounds

Section 4.1: The Variety of Compounds

Objectives: Distinguish the properties of compounds from those of the elements of which they are composed, Compare and contrast the properties of sodium chloride, water and carbon dioxide

What is an element?

What is a compound?

How do they differ?** Compound formation is only a

rearrangement of valence electrons**

Physical/Chemical Properties of Salt:Compound; Chemical Formula: NaCl1. white solid at 200C2. crystalline shape3. brittle4. melts at 8000C5. dissolves easily in water6. non-conductor when solid, but conducts

when molten/liquid7. nonreactive/stable compound

NaCl

Properties of Sodium Element; Symbol: Na1. shiny, silvery-white, soft solid at room temp2. melts at 980C3. reacts with oxygen to form sodium oxide,

Na2O

4. reacts with water to form hydrogen gas, and sodium hydroxide, NaOH (this is why its pure form is stored in oil)

5. never found free in the environment b/c of its high reactivity

Sodium

http://www.youtube.com/watch?v=MTcgo46nxNE

Properties of Chlorine

Element; Symbol: Cl2 (this is what’s called a diatomic element)

1.pale green, poisonous, gas @ room temp2. odor3. kills living cells, disinfects4. boiling point is a mere –340C5. among the most reactive elements

Chlorine

Reaction of Sodium and Chlorinehttp://www.youtube.com/watch?v=Mx5JJWI2aaw

Physical/Chemical Properties of Carbon Dioxide:

Compound; Chemical Formula: CO2

1. colorless gas at room temp2. slightly soluble in water3. freezing point = -800C, DRY ICE4. relatively stable; puts out fire5. ingredient in photosynthesis6. tasteless and odorlesshttp://www.youtube.com/watch?v=e7tf2MeXuQghttp://www.youtube.com/watch?v=8AN_XMcD3yI

Properties of CarbonElement; Symbol: C1. fairly unreactive solid at room temp2. at higher temps, will react with MANY

elements3. burns easily and is an excellent heat source4. carbon compounds are the basis of all living

things

Carbon

Properties of OxygenElement; Symbol: O2

1. colorless, odorless, tasteless2. supports combustion (it is not flammable by

itself)3. slightly soluble in water4. very reactive5. 21% of air you breathe6. most abundant element in the Earth’s crust

Oxygen

Physical/Chemical Properties of Water

Compound; Chemical Formula: H2O

1. gas at 1000C2. solid at 00C3. non-conductor (when distilled or pure)4. great solvent5. stable6. good medium for other reactions to occur in7. other ingredient in photosynthesis

Water (H2O)

Properties of Hydrogen1. Lightest most abundant element in the

universe2. Odorless, tasteless, colorless nonmetal gas3. Reactive compound that occurs in a variety

of compounds4. Does not conduct electricity and only slightly

soluble in water

Hydrogenhttp://www.youtube.com/watch?v=s0zxF66nb

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