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Week7Presentation.pptxSELECTED
ELEMENTS
Hydrogen
- the first element to appear on the Periodic Table of the Elements
- in its gaseous state at room temperature
- considered the smallest, lightest and simplest element known
- the most abundant element in the universe
“water-former”
- pure molecular hydrogen is a colorless, odorless, and tasteless gas
- the word hydrogen means
- when it is isolated from other substances, it exists as a pair of hydrogen atoms linked together by means of the covalent bond
- an important constituent of inorganic compounds such as water, acid and base compounds, and present in acid and base salts
Oxygen
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the most abundant element on Earth
pure oxygen is a colorless, odorless, tasteless gas
a natural component of air
- compounds which contain oxygen are called oxides
- occurs naturally as a diatomic molecule, O2
- 3 oxygen atoms chemically united by the electrification of air is called ozone, O3
Oxidation
1)
2)
3)
Addition of oxygen to a substance
Removal of hydrogen from a substance
A loss of electrons
There are several ways oxidation can occur
1. Slow Oxidation
- the oxidation of a substance at a relatively low temperature
- the rusting of metal is an example of slow oxidation, Fe2O3
2. Rapid Oxidation
- the oxidation of a substance at a relatively high temperature
the burning of wood is an example of rapid oxidation
| C6H12O6 | + | 6 O2 | = | 6 CO2 | + | 6 H2O |
- rapid oxidation occurs when the kindling point of a substance is reached
- the kindling point of a substance is
- that temperature at which a substance bursts into flame producing heat and light
- rapid oxidation can also be referred to as Combustion
3. Decay
4. Putrefaction
- the slow oxidation of organic matter caused by aerobic bacteria
- the slow oxidation of organic matter caused by anaerobic bacteria
Halogen Elements
- Group 7 on the Periodic Table
-classified as active non-metal elements
-naturally occur as diatomic molecules
-are present in typical inorganic binary acid compounds
- the most typical members of this group are Chlorine, Bromine, Fluorine and Iodine
- they form salts when chemically united with metal elements
- Chlorine is the most familiar halogen element
- often used as a bleaching agent and a disinfectant
Nitrogen
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a component of the air
especially amino acids, enzymes and proteins
a constituent in many organic compounds
nitrogen based organic compounds readily combine with formaldehyde to produce a decomposition resistant substance called Protein Coagulate
