Just a few elements, (usually bonded with other elements in compounds), make up most the

matter on Earth.

75 % of Earth is covered by….saltwater.

Saltwater is a mixture of two compounds.

Water = H2O

Salt = NaCl

Based on this…what are the two most common elements in our oceans?

Decode the compound formulas –

Water – H2OH = HydrogenO = Oxygen

Salt – NaClNa = SodiumCl = Chlorine

Percentage of Elements in the

Hydrosphere / Oceans

Element %

Oxygen (O) 85.84

Hydrogen (H) 10.82

Chlorine (Cl) 1.94

Sodium (Na) 1.08

Magnesium (Mg) .13

This graph shows the composition of our…

Atmosphere

Is Oxygen (O) the most important element in our atmosphere?

Is Oxygen (O) the most abundant element in our atmosphere?

Only if you like breathing.

NO!N – (N) Nitrogen = 78%O – (O) Oxygen = 21%

About 1 % of the atmosphere includes traces of other element and… two important compounds.

CO2 Carbon Dioxide…plants need this.

H2O Water Vapor (gas)…amount is variable.

The Earth’s Lithosphere /crust is dominated by 5 compounds.

Compound % mass

Silicon dioxide SiO2 43%

Magnesium oxideMgO 35%

Ferrous oxide FeO 9%

Aluminum oxide Al2O3 7%

Calcium oxide CaO 4%

What do they all have in common?

Oxygen (O)

Crust Elements% by mass

Oxygen (O) 47%Silicon (Si) 28%Aluminum (Al) 8%

Iron (Fe) 5%Calcium (Ca) 4%

Compound % mass

Silicon dioxide SiO2 42%

Magnesium oxide MgO 35%

Ferrous oxideFeO 9%

Aluminum oxide Al2O3 7%

Calcium oxide CaO 4%

These are the elements found in the abiotic (non living) parts of

Earth’s Lithosphere / Crust.

Common Elements for Biotic Matter

Bio = lifeIn the

BIOSHPHERE

Life ? Life =

•Grow•Reproduce•Respond •Use Energy

C Carbon

H Hydrogen

N Nitrogen

O Oxygen

Four elements are always found in living systems.

C6H12O6

sugar / carbohydrate

CO2

H2O

N

N

This is the chemistry of PHOTOSYNTHESIS !

C Carbon

H Hydrogen

N Nitrogen

O Oxygen

Remember

“CHNOPS”(“sha nops”)

“ORGANIC COMPOUNDS” are bonded with the following elements

P Phosphorus

S Sulfur