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Chemistry
is the basis for how the body transforms and uses energy and for how our cells use molecules such as carbohydrates, lipids, proteins, and nucleic acids
Matter
is anything that occupies space and has mass
Weight
is a measure of gravity pulling on mass
Chemistry
studies the nature of matter—how its building blocks are put together and how they interact
Matter
exists in solid, liquid, and gaseous states, all of which are found in the human body
Solids
such as bones and teeth, have a definite shape and volume
Liquids
have a definite volume, but they conform to the shape of their container
Gases
have neither a definite shape nor a definite volume
Matter
may be changed both physically and chemically
Physical changes
change that do not alter the basic nature of a substance
Chemical changes
do alter the composition of the substance—often substantially
energy
the ability to do work or to put matter into motion
kinetic energy
when energy is actually doing work (moving objects)
potential energy
When energy is inactive or stored (as in the batteries of an unused toy)
Chemical energy
is stored in the bonds of chemical substances
Electrical energy
results from the movement of charged particles
Mechanical energy
is energy directly involved in moving matter
Radiant energy
travels in waves; that is, it is the energy of the electromagnetic spectrum, which includes X rays, infrared radiation (heat energy), visible light, radio, and ultraviolet (UV) waves
elements
unique substances that cannot be broken down into simpler substances by ordinary chemical methods
periodic table
A complete listing of the elements
atoms
Each element is composed of very similar parti- 2 cles, or building blocks, called _____.
atomic symbol
We designate each element by a one- or two-letter shorthand name called an _____.
subatomic particles
Atoms, although indescribably small, are clusters of even smaller components called _____.
Protons (p+)
have a positive charge
neutrons (n0)
are uncharged or neutral
electrons (e2)
bear a negative charge equal in strength to the positive charge of the protons
planetary model
portrays the atom as a miniature solar system
orbital model
depicts the general location of electrons outside the nucleus as a haze of negative charge
atomic number
A number that is given to each element, that is equal to the number of protons its atoms contain
atomic mass number (or just mass number)
is the sum of the masses of all the protons and neutrons contained in its nucleus
isotopes
The atoms of almost all elements exhibit two or more structural variations; these varieties are called _____.
radioisotopes
The heavier isotopes of certain atoms are unstable and tend to release energy in order to become more stable; such isotopes are called _____.
radioactivity
process of spontaneous atomic decay
molecules
When two or more atoms combine chemically, _____ are formed
compound
When two or more different atoms bind together to form a molecule, the molecule is more specifically referred to as a molecule of a _____.
