Chemistry Flashcards
define atom
the building block of all matter
difference between molecule and compound
a molecule is a number of atoms bonded together while a compound is two or more different atoms bonded together
define isotope
An isotope is when atoms of the same element contain the same number of protons but different number of neutrons
three types of radioactive decay
alpha, beta and gamma
what is alpha radiation
Emits a helium nucleus
is a particle
has a positive charge
moves relatively slowly
is large
low penetrating power ( paper stops it)
what is beta radiation
emits an electron
is a particle
negative charge
moves fast (99% of speed of light)
is small
medium penetrating power ( stopped by plastic)
what is gamma radiation
is a wave, only energy
no charge
speed of light
very small
high penetrating power (stopped by a thick layer of concrete or lead)
define radioactive decay
Radioactive decay is when the nucleus of an unstable isotope releases energy by emitting radiation
why do atoms undergo radioactive decay
To become more stable
Groups and periods
groups are x value and periods are y value
Define half life
how long it takes for half of a radioactive atom to decay
define cation
a positive version of an atom that has lost electrons
two uses of isotopes
Radiotherapy to treat cancer
X-rays used in medical imaging
define ion
a charged version of an atom that has either lost or gained electrons
why do atoms become ions
to become stable with a full outer shell of electrons
