mixture
any combination or blend of different elements, kinds, qualities, etc.:
molecule
Chemistry, Physics. the smallest physical unit of an element or compound, consisting of one or more like atoms in an element and two or more different atoms in a compound.
momentum
force or speed of movement; impetus, as of a physical object or course of events:
moon phase
motion
the action or process of moving or of changing place or position; movement.
mutation
a sudden departure from the parent type in one or more heritable characteristics, caused by a change in a gene or a chromosome
natural selection
the process by which forms of life having traits that better enable them to adapt to specific environmental pressures, as predators, changes in climate, or competition for food or mates, will tend to survive and reproduce in greater numbers than others of their kind, thus ensuring the perpetuation of those favorable traits in succeeding generations.
neutron
n elementary particle having no charge, mass slightly greater than that of a proton, and spin of ½: a constituent of the nuclei of all atoms except those of hydrogen.
nonliving
having life; being alive; not dead:
nonrenewable resource
any natural resource from the Earth that exists in limited supply and cannot be replaced if it is used up; also, any natural resource that cannot be replenished by natural means at the same rates that it is consume
nucleus
a central part about which other parts are grouped or gathered; core:
observe
to see, watch, perceive, or notice:
