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24 terms

Chapter 2 - The Chemical Context of Life

Basics of chemistry
STUDY
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matter
anything that takes up space and has mass
element
any substance that can't be broken down to any other substance by chemical reactions
compound
a substance consisting of two or more different elements combined in a fixed ratio
essential element
essential for life (for plants life cycle) can be in big and small amounts
trace element
element indispensable for life but required in extremely minute amounts
neutron
a subatomic particle having no electrical charge (electrically neutral) 1.7x10-24 g in nucleus
proton
a subatomic particle with a single positive charge, 1.7x10-24 g in nucleus
electron
a subatomic particle with a single negative charge & a mass of about 1/2000 that of a neutron/proton, on or more move around the nucleus of an atom
atomic number
the number of protons in the nucleus of an atom, unique for each element & designated by a superscript to the left of the element symbol
atomic mass
the total mass of an atom, which is the mass in grams of one mole of the atom
isotope
one of the several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass
electron shells
an energy level of electrons at a characteristic average distance from the nucleus of an atom
energy
the capacity to cause change, especially to do work (to move matter against an opposing force)
potential energy
energy that matter possesses as a direct result of its location or spatial arrangement (structure)
molecule
two or more atoms held together by a covalent bond
double bond
the sharing of two pairs of valence electrons by two atoms
electronegativity
the attraction of a given atom for the electrons of a covalent bond, some have stronger pull than others
nonpolar covalent bond
one in which electrons are shared equally between to atoms of similar electronegativity, such as O2 or H2
polar covalent bond
one between atoms that differ in electronegativity, the shared electrons are pulled closer to the more elctronegative atom, making it slightly negative and the other atom slightly positive
anion
a negatively charged ion
cation
a positively charged ion
hydrogen bond
a type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule
van der Waals interactions
weak attractions between molecules or parts of molecules that result from localized charge fluctuations, they occur only when atoms and molecules are very close together
dynamic equilibrium
the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products don't change with time, it only implies that their concentrations have stabilized at a particular ration