FINALS RADTHERA PART 2 (ATOM & RADIOACTIVITY)

ATOMOS

means indivisible

atom

___ was the smallest indivisible component of matter according to some philosophers in Ancient Greece.

protons, neutrons, electrons

However, we now know that atoms are actually composed of subatomic particles:___

atom

Fundamental building blocks of matter

atom

Smallest particle of an element

atom

Neutral charged

electrons

principal parts of atom in an ORBITAL SHELL

neutrons and protons

principal parts of atom inside the NUCLEUS

Neutral Atom

Consists of same number of protons and electrons

Ionized Atom

-- Consists of an extra or a lacking of e

– Can be positive or negative

ORBITAL SHELL

• Consists of electrons

ORBITAL SHELL

Consists of 7 orbital shells ‒ K-shell (innermost) to Q-shell (outermost)

ORBITAL SHELL

Each shell represents different electron binding energy (Eb)

NUCLEUS

Central core of an atom

NUCLEUS

Contains protons and neutrons

NUCLEUS

Contains nearly all mass of the atom

NUCLEUS

Positively charged

GROUP NUMBER and VALENCE STATE

Number of electron (outermost shell)

PERIOD NUMBER

Number of outermost electron shell

ELECTRON BINDING ENERGY

The strength of attachment of an electron to the nucleus

ELECTRON BINDING ENERGY

The energy required to completely remove an electron from the atom

ELECTRON BINDING ENERGY

Symbol: Eb

the higher the Eb

The closer the electron to the nucleus,___

Inner shell

Higher Eb, Difficult to remove

Outer shell

Lower Eb, Easy to remove

CHEMICAL SYMBOL

Alphabetic abbreviation of an element

CHEMICAL PROPERTIES

Determined by the Number & Arrangement of electrons

ATOMIC NUMBER

The number of protons in an atom

ATOMIC NUMBER

Symbol: Z

ATOMIC MASS NUMBER

The number of protons and neutrons (nucleons)

ATOMIC MASS NUMBER

▪ Symbol: A

NEUTRON NUMBER

The difference between the atomic mass number and atomic number

isotopoes

isotones

isobars

isomers

atoms have been classified into

Isotopes

same number protons, different number neutrons

Isotones

same number neutrons, different number protons

Isobars

Same number nucleons, different number protons

Isomers

Same number protons and neutrons.

Isomers

differ in their nuclear energy states.

Antonio Henri Becquerel 1896.

Radioactivity is first discovered by

RADIOACTIVE ATOM

A phenomenon in which radiation is given off by the nuclei of the elements.

particles, electromagnetic radiation, or both.

This radiatioactove atom can be in the form of ___

α particles

___ (helium nuclei) are positively charged

β- particles

___ (electrons) are negatively charged

opposite directions

Since α particles are positively charged and β- particles are negatively charged, they are deflected in ___

heavier

The difference in the radii of curvature indicates that α particles are much ___ than β particles.

γ rays

____ which are similar to x-rays except for their nuclear origin, have no charge and, therefore, are unaffected by the magnetic field.

potential barrier

There is a ___ preventing particles from entering or escaping the nucleus.

kinetic

Although the particles inside the nucleus possess ___ energy, this energy, in a stable nucleus, is not sufficient for any of the particles to penetrate the nuclear barrier.

radioactive nucleus

___ has excess energy that is constantly redistributed among the nucleons by mutual collisions.

emission of a particle

the ___ may still leave the nucleus in an excited state.

particles or γ rays

the nucleus will continue stepping down to the lower-energy states by emitting ____ until the stable or the ground state has been achieved.

Radioactivity

___is the spontaneous emission of particles and energy in order to become stable.

radionuclides

The atoms involved in radioactivity are___

nuclide

Any nuclear arrangement is called a ___

radionuclides

only nuclei that undergo radioactive decay are ___

intranuclear electron or helium nucleus

An unstable atomic nucleus sheds its excess energy in the form of either an ___ or a ___

gamma rays

If an unstable atomic nucleus still possesses excess energy after that,___ are emitted in order to reach its steady state.

PARENT

‒ Original radionuclide

‒ Very unstable

‒ Longer half-lives

‒ Excited stated

DAUGHTER

‒ Resulting radionuclide

‒ More stable

‒ Shorter half-lives

‒ Ground state

PHYSICAL HALF-LIFE

time required for a quantity of radioactivity to be reduced to onehalf its original value.

unique HLV

in physical half life, Every radioactive material has its own ___.

never disappears

in physical half life All radioactivity ____.

zero

in physical half life Quantity decreases but never reaches ___.

REMAINING ACTIVITY = ORIGINAL ACTIVITY (0.5)n

RADIOACTIVE DECAY FORMULA

BIOLOGICAL HALF-LIFE

time required for the body to eliminate one-half of the dose of any substances by biological processes.

BIOLOGICAL HALF-LIFE

Determined by the clearance of the radionuclides from the organ, tissue or body

physiologic processes

Most radiopharmaceuticals are also cleared from organs by various ___

EFFECTIVE HALF-LIFE

A combination of both T1/2 and Tb

EFFECTIVE HALF-LIFE

time required for half of initial radioactivity to disappear from an organ or body by combination of excretion and physical decay

charged particles,

Particles of ionizing radiation include ____ such as alpha particles, protons, electrons, beta particles, and positrons, and uncharged particles, such as neutrons.

different

The behavior of heavy charged particles is ___ from that of lighter charged particles such as electrons and positrons.

Electrons

due to their negative charge and low mass, can be accelerated to high energies in linacs or betatrons.

positively charged

Electrons are normally bound to a ___ nucleus

equal

number of electrons is ___ to the number of protons in a neutral atom.

excitation, ionization, radiative losses.

Energetic charged particles all interact with matter by electrical forces and lose kinetic energy via ___, ___, and ___

Excitation, ionization

___ and ___occur when charged particles lose energy by interacting with orbital electrons.

coulombic forces

▪These interactional, or collisional, losses refer to the ___ exerted on charged particles when they pass in proximity to the electric field generated by the atom’s electrons and protons.

Excitation

___ is the transfer of some of the incident particles' energy to electrons in the absorbing material

Excitation

Occurs when energy transferred to an electron does not exceed its binding energy

de-excitation

occurs as the electron returns to a lower energy level releasing energy

electromagnetic radiation

de-excitation is emitted in the form of____

Auger electron

de-excitation is emitted in the form of Transferring the energy to a weakly bound orbital electron which is ejected as an ___

SECONDARY IONIZATION

Occurs when transferred energy exceeds the binding energy

Electron

___is ejected from the atom

ion pair

secondary ionization results in an___ consisting of an ejected electron and a positively charged atom

delta rays

Secondary ionization occurs when the ejected electron has sufficient energy to produce further ionization, these electrons are called ___

decreases, increases

for radiative losses, as electron energy ___, the probability of energy loss via excitation ___

ion pairs (IP)/mm

The number of primary and secondary ion pairs produced per unit length of the charged particle’s path is expressed in ___

increases , decreases

Specific ionization ___with the square of the electrical charge (Q) of the particle and ___with the square of the incident particle velocity.

larger charge

A ___ produces a greater coulombic field;

7,000 IP/mm, 10 million IP/mm

An alpha particle can have as high as ____ in air and about ___ in soft tissue

Bragg peak

As the alpha particle slows, the specific ionization increases to a maximum called the ___

electrically neutral

As the alpha particle decreases rapidly, alpha particle picks up electrons and becomes___

tortuous paths

Electrons follow ___ in matter as the result of multiple scattering events caused by coulombic deflections (repulsion and/or attraction)

Heavy charged particle

___ results in a dense and usually linear ionization track

Alpha particle

___ has a larger mass results in a dense and usually linear ionization track.

Path length

Defined as the actual distance the particle travels.

Range

Defined as the actual depth of penetration of the particle in matter.

always exceeds

The path length of the electron almost ___ its range.

nearly equal

The path length and range of the alpha particle is being ___.