Chapter 2 Flashcards
Matter
Anything that takes up space and has mass.
Element
Any substance that cannot 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
A chemical element required for an organism to survive, grow, and reproduce.
Trace element
An element indispensable for life but required in extremely minute amounts.
Atom
The smallest unit of matter that retains the properties of an element.
Neutron
A subatomic particle having no electrical charge (electrically neutral), with a mass of about 1.7x10 g, found in the nucleus of an atom.
Proton
A subatomic particle with a single positive electrical charge, with a mass of about 1.7x10 g, found int he nucleus of an atom.
Electron
A subatomic particle with a single negative electrical charge and mass about 1/2000 that of a neutron or proton.
One or more electrons move around the nucleus of an atom.
Atomic nucleus
An atoms dense central core, containing protons and neutrons.
Dalton
A measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu.
Atomic number
The number of protons in the nucleus of an atom, unique for each element and designated by a subscript.
Mass number
The sum of the number of protons and neutrons in an atoms nucleus.
Atomic mass
The total mass of an atom, numerically equivalent to the mass in grams of 1 mole of the atom.
(For an element with more than one isotope, the atomic mass is the average mass of the naturally accruing isotopes, weighted by their abundance.
Isotope
One of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing the atomic mass.
Radioactive isotope
An isotope (an atomic form of a chemical element) that is unstable
The nucleus decays spontaneously, give off detectable particles and energy.
Half-life
The amount of time it takes for 50% of a sample of a radioactive isotope to decay.
Radiometric dating
A method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes.