Human History and Material Science: From Stone to Polymers
ITEM 7. Humans and Materials
7.1 The First Materials
A. It All Started with a Couple of Stones
It is estimated that the beginning of the use of materials made by man was about 2.5 billion years ago. The Stone Age was followed by the Bronze Age and the Iron Age.
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Stone Age
Edged stones were refined, and eventually, axes, arrows, spears, knives, and many other tools appeared that facilitated their daily activities. The Stone Age was born, and so was technology.
Humans worked in tunnels and caves to find
Atomic Theory: From Dalton to Bohr and Beyond
Dalton’s Atomic Theory
Dalton’s atomic theory states that:
- All matter is made up of atoms.
- Atoms are indivisible and indestructible.
- All atoms of a given element are identical in mass and properties.
- Compounds are formed by a combination of two or more different kinds of atoms.
- A chemical reaction is a rearrangement of atoms.
Atoms
Atoms are the smallest particles of everything. There are three basic parts of an atom: electrons, protons, and neutrons. The thing that makes each of those elements different
Read MoreChemistry: Definition, Areas, Fields, and Environmental Impact
Definition of Chemistry
Central science of all experimental sciences. It studies the composition, structure, properties, and behavior of matter and the changes it undergoes in interactions.
Areas of Study of Chemistry
Organic: The branch of chemistry that deals with the structure, properties, and reactions of compounds that contain carbon.
Inorganic: The study of the synthesis and behavior of inorganic and organometallic compounds.
Analytical: The study of the separation, identification, and quantification
Read MoreUnderstanding Chemical Reactions: Equilibrium, Acids, Bases, and Redox
Chemical Balance
At the beginning of a reversible reaction, as the concentrations of the reactants are large, the reaction rate will also be great in the sense of the first member to the second. But as you proceed through the process and product concentrations begin to be significant, the reaction rate will increase in the opposite direction, i.e., in the sense of the second member to the first. There will come a time when both speeds are equal. At that moment, as many molecules are recomposed as
Read MoreSpectroscopy and Chromatography Techniques
Vibrational Spectra (IR Spectra)
IR spectroscopy is concerned with the study of absorption of IR radiation (800nm- 1mm), which causes vibrational transition in the molecule. When a gaseous molecule absorbs IR radiation, it produces transition between the vibrational energy levels. The resultant spectrum is called vibrational spectra. The essential requirement for a molecule to produce an IR spectrum is that the dipole moment of the molecule must change during vibration. Thus, a vibrational spectrum
Carbohydrates, Lipids, and Proteins: Essential Biomolecules
Carbohydrates
Carbohydrates are compounds composed of carbon (C), hydrogen (H), and oxygen (O). Their general formula is Cn(H2O)n. They are derived from polyalcohols, aldehydes (aldoses), and ketones (ketoses).
Classification
- Monosaccharides: Consist of one molecule, containing 3-7 carbon atoms. They are sweet, soluble, and crystallize (sugars).
- Disaccharides: Formed by the binding of two monosaccharide molecules.
- Oligosaccharides: Composed of several monosaccharide molecules (approximately 10-12).
- Polysaccharides: