Chapter 2: The Chemical Context Of Life

Front 1

Matter

Back 1

anything that takes up sace and has mass

Front 2

Element

Back 2

Substance that cannot be broken down to other substances by chemical reactions

Front 3

Compound

Back 3

substance consisting of two or more different elements combined in a fixed ratio

Front 4

Trace elements

Back 4

are those required by an organism in only minute quantities

Front 5

Atom

Back 5

smallest unit of matter that still retains the properties of an element

Front 6

Dalton

Back 6

A measure of mass for atoms and subatomic particles. neutrons and protons have mass close to 1 dalton

Front 7

Atomic Number

Back 7

the number of protons, which is unique to that element

Front 8

Mass Number

Back 8

the sum of protons plus neutrons in the nucleus of an atom

Front 9

Atomic mass

Back 9

the mass number is an approximation of the total mass of an atom called atomic mass

Front 10

Isotopes

Back 10

One of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass.

Front 11

Radioactive Isotope

Back 11

one in which the nucleus decays spontaneously givving off particles and energy

Front 12

Energy

Back 12

the capacity to cause change for instance by doing work

Front 13

Potential energy

Back 13

the energy that matter possesses because of its location or structure

Front 14

Energy levels

Back 14

the different states of potential energy that electrons have in an atom

Front 15

Electron shells

Back 15

An electron's energy level is correlated with its average distance from the nucleus; these average distances are representd symbolically by electron shells