* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download The Nature of Molecules
Photoelectric effect wikipedia , lookup
Molecular Hamiltonian wikipedia , lookup
Physical organic chemistry wikipedia , lookup
Electrical resistivity and conductivity wikipedia , lookup
Computational chemistry wikipedia , lookup
Low-energy electron diffraction wikipedia , lookup
Nuclear transmutation wikipedia , lookup
Periodic table wikipedia , lookup
Livermorium wikipedia , lookup
Nuclear binding energy wikipedia , lookup
Bent's rule wikipedia , lookup
Chemical element wikipedia , lookup
Molecular orbital wikipedia , lookup
Bond valence method wikipedia , lookup
X-ray fluorescence wikipedia , lookup
Metastable inner-shell molecular state wikipedia , lookup
X-ray photoelectron spectroscopy wikipedia , lookup
Isotopic labeling wikipedia , lookup
Metalloprotein wikipedia , lookup
Electronegativity wikipedia , lookup
Molecular dynamics wikipedia , lookup
History of chemistry wikipedia , lookup
Resonance (chemistry) wikipedia , lookup
Atomic orbital wikipedia , lookup
Extended periodic table wikipedia , lookup
Chemistry: A Volatile History wikipedia , lookup
IUPAC nomenclature of inorganic chemistry 2005 wikipedia , lookup
Molecular orbital diagram wikipedia , lookup
Hypervalent molecule wikipedia , lookup
Rutherford backscattering spectrometry wikipedia , lookup
Atomic nucleus wikipedia , lookup
Metallic bonding wikipedia , lookup
Electron configuration wikipedia , lookup
Chemical bond wikipedia , lookup
The Nature of Molecules Our study of life begins with physics and chemistry – as life, itself, is a chemical machine 1st, some definitions • Matter = any substance having mass and which takes up space; all matter is composed of atoms • Atoms = the simplest/smallest component of matter; composed of nucleus and electron orbital(s) – # of protons = Atomic number – # of protons + neutrons = Atomic mass • Naturally-occurring atoms on Earth = 90 • Diagram of typical atomic structure: • Atomic #/mass of: H, He, C, O, N, S, P, Ne Fig. 2.2.a Isotopes • All atoms of an element contain the same number of protons, but not the same number of neutrons • Atoms possessing different numbers of neutrons are isotopes – Ex: Carbon has 3 isotopes (99% have 6 neut’s) = 12C there is also 13C and 14C (14C is a radioactive isotope with a half-life of 5730 years) • Isotopes are commonly used in research and in medicine Fig. 2.3 Electrons • Negatively charged particle(s) which orbit the nucleus • Electrons may be lost or gained from one atom to another to form a charged atom or ion….e.g., Na + Cl (formation of cation/anion) • # of electrons determines the behavior, hence chemical activity of an atom Fig. 2.4 Electrons and energy levels • There are discrete energy levels surrounding the nucleus of an atom; one level contains only 1 orbit of electrons, others contain 4 different orbits of electrons (each orbit is filled with 2 e-’s) • The filling of orbitals and energy levels relates to the chemical behavior of atoms • The number of electrons of an atom relates to its valence • Valence relates to how one atom reacts with another Fig. 2.7 Fig. 2.5 ***Inner energy shells (those closest to the nucleus) contain electrons with lower energy than the outer energy shells ***important concept as it will be discussed in the Light Dependent reaction of Photosynthesis The elements of biology • The large biomolecules which comprise life are composed, primarily, of 6 elements: CHONPS (98.9%) = all having low atomic masses….check it out…… • Examples of biomolecules: • These elements contain valences that dictate how they react with other atoms of elements => through covalent bonds. Chemical bonding • Bonding occurs between interacting atoms in several ways; mainly through: – loss/gain of electron from one atom to another = Ionic bonding (found in salts and other crystalline molecules) Or -sharing of electrons between atoms = covalent bonding (found in biomolecules) Fig. 2.8.a Ionic bonding of NaCl (Sodium chloride) Sodium (Na) losses an e- and Chlorine (Cl) gains an e-; hence charged atoms (ions) form and are attracted to one another Page 24 Covalent bonding of some common gases Lastly, some definitions: • A group of at least 2 atoms joined together by a chemical bond is called a molecule • A molecule that contains more than one element is called a compound