Understanding Atoms, Molecules, and States of Matter
Atom
The matter consists of atoms. These consist of the nucleus and cortex. The core is formed by protons (p+) and neutrons (n). The crust consists of electrons (e–).
Ions
An atom can become an ion by electron gain or loss. If it gains electrons, it becomes an anion (negatively charged ion). If it loses electrons, it produces a cation (positively charged ion).
Atomic Number (Z)
The atomic number is the number of protons in the nucleus of an atom. It identifies the atoms of an element. This matches the
Read MoreUnderstanding Amino Acid Properties and Protein Structure
Amphoteric Character
Amino acids possess an amphoteric character due to the presence of both carboxyl and amino groups. The carboxyl group can lose a proton, acting as an acid, while the amino group can accept a proton, acting as a base. This dual behavior allows amino acids to act as both acids and bases depending on the pH of the environment. The side chain may also contain ionizable groups, further influencing the amino acid’s charge.
Isoelectric Point
The isoelectric point (pI) is the pH at which
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Amino Acids: The Monomers of Proteins
Amino acids are the building blocks of peptides and proteins. Over twenty amino acids are found in proteins and are common to all living organisms.
Molecular Structure
All protein amino acids share a common structure: an amino group (-NH2), which is basic, and a carboxyl group (-COOH), which is acidic. They also have a unique side chain (R group) that varies among different amino acids.
Classification of Amino Acids
Amino acids are classified into four groups based
Read MoreAtmospheric Chemistry: Composition, Reactions, and Environmental Impact
Steady state balance between protons and electrons. Rocks = eruptive volatile atmosphere + sea water sediments. Determined by atmospheric composition, seawater pH, redox potential of 0.75. Non-photosynthetic microorganisms act as catalysts. pE = E / 2.303RT / F in 25 ºC.
pE0 = E0 / 2.303RT / F in 25 ºC. F = Faraday constant. pE = -log (ae-). It accounts for the effects of different electrode potential activities. Fe3+ + e– ⇌ Fe2+, E0 = +0.77 volts, pE0 = 13.2. The Nernst equation is: E = E0 +
Read MoreChemical Equilibrium, Reaction Rates, and Solutions
Mass Action Law
The mass action law states that the value of the equilibrium constant Kc is constant for a particular reaction at a constant temperature, provided that equilibrium concentrations are used. The mathematical expression representing the equilibrium constant at a certain temperature is:
aA + bB ⇌ cC + dD
Kc = ([C]c[D]d) / ([A]a[B]b)
This shows that the equilibrium constant is the ratio of the product concentrations to the reactant concentrations, each raised to the power of their stoichiometric
Read MoreIntermolecular Forces, Thermodynamics, and Chemical Kinetics
Intermolecular Forces
F. Orientation/Permanent Dipole-Dipole
Dipoles are oriented; the positive pole of one molecule attracts the negative pole of the nearest molecule. The force (F) of attraction increases with polarity. This is present in liquids and gases. Examples of weak attractions include HCl, NH3, H2O, and ethanol.
F. Dispersion/London Forces
These forces occur between nonpolar molecules due to instantaneous dipoles caused by electron vibration. The force value increases with molecular mass
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