7/26/2019 Physics of the Atom Concept Map

1/1

E=mc2 is an equation derived by the twentieth-century physicist Albert Einstein, in

which Erepresents units of energy,mrepresents units of mass, and c2is the speed of

light squared, or multiplied by itself. Since the speed of light is a very large number and

is multiplied by itself, this equation points out how a small amount of matter can release

a huge amount of energy, as in a nuclear reaction.

-particles -particles -radiation

Identity Helium nuclei ast moving

electrons

Electromagnetic

radiation of high

frequency ! "#$%$&H'

Charge (( -$ none

Mass compared with proton ) !$*$+)% none

Can it affect a photographic

plate?

yes yes es

Does it case florescence? es yes yes

It is stopped !y cm"of air or a

sheet of paper

A few mm of

aluminum

several cm of lead

"enetrating power

#relati$e%

$ $%% $%%%%

Ioni&ing power

#relati$e%

$%%%%

strong/

$%%

moderate/

$

0ea1/

"ath 'hrogh matter straight bent straight

Is it deflected !y a magnetic

field?

yes yes no

Is it deflected !y an electric

field?yes yes no

he method employed to detect radiationdepends on the type of emitter

and the intended purpose of detection. he most well-1nown method of

detecting radiation is with an ioni&ation cham!er. A high energy particle

can dislodge electrons from the atoms it stri1es, producing pairs of ions.3articles are allowed to pass between parallel plates, one with a positive

charge and one with a negative charge. As ioni'ation ta1es place the ions

each move to the plate with the opposite charge, producing a current. he

current is read on a meter. he 4eiger-5ueller counter is based on the

ioni'ation detection principle.

3hotographic film can be e#posed by all types of radiation, and is

used to monitor e#posure of personnel wor1ing with high energy

emitters. A visible trac1 in a clod or !!!le cham!ercan pic1 up

radioactivity, as can a calorimeter if the energy emitted is quite high.

(ear )ame of

*trctre

Creator Description

+,. 3lum 3udding5odel

6.6homson

Electrons are embedded in a diffuse sphere of positive

charges.

his model did not account for the case with which

electrons could be 1noc1ed off from atoms

+++ 3lanetary

5odel

7utherford 5odel resembles that of a solar system where the nucleus

plays the role of the sun and the electrons play the role of

the orbiting planets.

++/ he 8ohr

Atom

9eils 8ohr he electrons in an atom occupy permissible shells each

of which can hold a ma#imum number of electrons

he outer occupied shell is 1nown as the valance shell.

+/2 :hadwic1 ound that neutrons could not account for the mass of the

nucleus and thus was later discovered. 9eutron was found to be natural in

charge with mass close to that of proton

"articles *ym!ol 0elati$e

Mass

0elati$e

charge

1ctal Mass

Electron e $*$+)% -$ 9.10938215(45)

10-31 kg"roton 3 $ ($ 1.672621637(83)

1027 kg)etron 9 $ -% 1.67492729(28)

1027. kg

0adioacti$ity is the process by which a nucleus of an unstable atom loses

energy by emitting particles of ioni'ing radiation. A material that

spontaneously emits this 1ind of radiation- which includes the emission of

energetic alpha particles, beta particles, and gamma rays ; is considered

radioactive.

"hysics of the

1tom