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The Chemical Context of Life (bonds (covalent bonds: the sharing of a pair…
The Chemical Context of Life
elements
trace elements
about 20-25% of the 92 natural elements are required for life (essential elements)
carbon, hydrogen, oxygen, and nitrogen make up 96% of living matter
compound: two or more elements in a fixed ratio
compounds formed by ionic bonds are called ionic compounds, or salts
subatomic particals
neutrons: no charge
protons: positive charge
electrons: negative charge
atoms: are composed of subatomic particals
atomic number: the number of protons in the atoms nucleus
atomic mass: the sum of protons and neutrons in the nucleus
atomic mass: the atoms total mass
electrons of an atom: differ in their amounts of potential energy
electron shell determines the state of their potential energy
the chemical behavior is determined by the distirbution of electrons
valence electrons: those in the most outer shell
atoms with a full outer valence shell are chemically inhert
valence: Bonding capacity is called an atoms valence
atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms
isotopes (ex: Carbon-12, Carbon-13, and Carbon-15)
radioactive isotopes
radioactive tracers
half-life: isotope decay
radiometric dating
bonds
single bonds: the sharing of one pair of valence electrons. (ex. H:H, H-H)
covalent bonds: the sharing of a pair of valence electrons by two atoms
electronegativity: an atoms attraction for the electrons
non-polar covalent bond: the atom shares the electron equally
polar covalen bonds: one atom is more electronegative and the atom do not share the electron equally
chemical bonds: interactions causing atoms to stay near each other, held by attractions
hydrogen bonds: hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom.
iconic bonds: an attraction between an anion and cation
Van der waals interactions:attractions between molecules that are close together for a brief amount of time
cation: positively charged ion
anion: negatively charged ion
molecular shape: how biological molecules recognize and respond to one another.
chemical reactions: making and breaking of chemical bonds
reactant: start
product: finish
chemical equilibrium: when the fowards and reverse reactions occur at the same rate.