Chem. Basis Of Life Flashcards
A substance consisting of two or more different elements combined in a fixed ratio. More common than pure elements.
Compound
An element that is essential for life but required in extremely minute amounts.
Trace elements
Smallest unit of matter that still retains the properties of an element. From Greek word meaning “indivisible”.
Atom
A subatomic particle with a single positive charge. (+)
Proton
A subatomic particle with a single negative charge. (-)
Electron
A subatomic particle having no electrical charge, found in the nucleus of an atom.
Neutron
(1) An atoms central core, containing protons and neutrons.
(2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin.
Nucleus (nuclei)
The number of protons in each atom of a particular element.
Atomic number
The sum of the number of protons and neutrons in its nucleus
Mass number
One of several atomic forms of an element, each with the same number of protons and behave Identically in chemical reactionS, but a different number Of neuTrOns.
Isotopes
An isotope whose nucleus decays spontaneously, giving of particles and energy
Radioactive isotope
A level of electrons at a characteristic average distance from the nucleus of an atom. (The out-laying layers around an atom. An atom may have one, two or more of these.)
Electron shells
Outer most Electron shell.
Valence shell
An attraCtion between two atoms resulting from a sHaring of outer-shell Electrons or the presence of opposite charges on the atoMs. The BONDed atoms gain complete outer Electron shells.
Chemical bonds
A type of strong chemical bond in which TWO atoms share one or more pairs of VALence electrons.
Covalent bond
Two or More atOms heLd together by covalent bonds.
Molecule
The attraction of a given atom for the ELECtroNs of a covalEnt bond.
Electronegativity
A COVALENT BOND between atoms that differ in electronegativity. The shared electrons are Pulled clOser to the more electronegative atom, making it sLightly negAtive and the otheR atom slightly positive.
Polar covalent bond
A type of COVALENT BOND in which electrons are shared equally between two atoms of similar electronegativity.
Nonpolar covalent bond
An atom or molecule with an electrical charge resulting from a gaIn Or loss of oNe or more electrons.
Ion
A chemical BOND resulting from the attraction between oppositely charged atoms.
Ionic bond
A compound resulting from the formation of an ionic bond. (Sodium chloride)
Salt
A type of weak chemical BOND 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 (or in another region of the same molecule.)
Hydrogen bond
A MOLECULE containing POLAR covalent bonds and having an unequal distribution of charges in different regions of the molecule.
Polar molecule
The MAKING AND BREAKING of chemical bonds, leading to changes in the composition of matter.
Chemical reactions
A starting material in a chemical REACTion.
Reactants
The material resulting from the chemical reaction.
Product
The tendency of molecules of the same kind to STICK together.
Cohesion
The CLINGing of one substance to another.
Adhesion
A measure of how difficult it is to stretch or break the surface of a liquid.
Surface tension
The ENERGY associated with THE Random Movement of Atoms and moLecules.
Thermal energy
Thermal energy in transfer from a warmer to a cooler body of matter.
Heat
Measures the intensity of heat, that is, the average speed of molecules in a body of matter.
Temperature
The process in which the surface of an object becomes cooler during EVAPORATION.
Evaporative cooling
A liquid consisting of a uniform mixture of two or more substances
Solution
The dissolving agent.
Solvent
A substance that is dissolved. Eg : salt
Solute
A solution in which water is the solvent.
Aqueous solution
Best described as a MINGLING of molecules and/or ions.
Dissolving
A substance that donates hydrogen (H+) ions to solutions.
Acid
A substance that reduces the hydrogen (H+) ion concentration of a solution.
Base
A measure of the acidity of a solution, ranging in value from 0 (most acidic) to 14 (most basic). [The letters pH stand for potential hydrogen and refer to the concentration of hydrogen ions (H+).]
pH scale
Substance that minimize changes in pH.
Buffers
Decreasing pH of ocean waters due to absorption of excess atmospheric CO2 from the burning of fossil fuels.
Ocean acidification
A substance that cannot be broken down to other substances by ordinary chemical means.
Element
