ATOMIC STRUCTURES RADIATION PRODUCTION & CHARACTERISTICS LIZ

Democritus

Greek Philosopher Suggested world was made of two things – empty space and

“atomos”

Atomos

Greek word for uncuttable

Atom

Smallest possible particle of matter

John Daltons

According to him all matter is made of atoms

John Dalton

He envisioned atoms as solid, hard spheres, like billiard(pool) balls, so he used wooden balls to model them

Billiard Ball

Dalton’s early atomic model

J.J. Thomson

Scientists who discovered the electron

J.J. Thomson

He was the first scientist to show that atom was made of even smaller things

J.J. Thomson

Used the Cathode ray tube to discover electrons

J.J. Thomson

Scientists uses “Plum Pudding” atom model

Eugen Goldstein

Using a cathode ray tube he discovered canal rays which are beams of positively charged particles. He is credited with the discovery of protons in an atom.

Eugen Goldstein

Scientists used Millikan’s Oil Drop Experiment

Millikan’s Oil Drop Experiment

Determined the charge on an electron Used Thomson’s charge to mass ratio to calculate the mass of an electron

Ernest Rutherford

Discovered the nucleus of a gold atom with his “gold foil” experiment

Nucleus

It is a small, dense core with a positive charge

Atom

Smallest particle of an element that can exist alone

Nucleus and Electron

Two region of an atom

Nucleus

Center of atom, protons and neutrons

Electron

Area surrounding nucleus containing electrons

amu(atomic mass unit)

Approximate mass of a proton or a neutron

Proton

It is Positive charge (+), has 1 atomic mass unit (amu); found in the nucleus

▪amu -Approximate mass of a proton or a

Neutron

It is Neutral charge (0), has 1 amu; found in the nucleus

Electron

It is a Negative charge (-), it mass is

VERY small

Atomic number

In counting atoms the number of protons is the __

Atomic mass(mass number )

In counting atoms the number of protons + neutrons is the __

Isotopes

Atoms of the same element with varying number of neutrons

Mass number

In counting atoms nuclear symbol notation A is the __

Atomic number

In counting atoms nuclear symbol notation Z is the __

Element

In counting atoms nuclear symbol notation X is the __

Negative

When an atom GAINS electrons it becomes

Positive

When an atom LOSES electrons it becomes

Cation

It is a positive ion

Anion

It a negative ion

Joule(J)

Basic unit of energy

electron volt(eV)

Another energy unit in nuclear physics is?

Radioactivity or Radioactive decay

The process by which atoms spontaneously emit high energy particles or rays from their nucleus.

Parent Nuclide

It is the original nuclide which undergoes radioactive decay

Daughter Nuclide

It is the more stable nuclide which results from radioactive decay.

Progeny

Another term of Daughter Nuclide

Nuclide

Any atomic species characterized by the number of protons and number of neutrons

Alpha particle

Emitted when the nucleus is too big

Alpha decay

Heavy nuclei more massive than Pb decay by this method

Beta particle

A fast moving electron originating from the nucleus

Beta particle

Emitted when the nucleus has too many neutrons

Gamma ray

Not a particle, but a burst of very high energy as electromagnetic radiations of very high frequency

Gamma ray

No mass, zero charge

Gamma decay

Only energy is released

Electron capture

Occurs in atoms with excess protons

Positron

Proton becomes neutron, neutron becomes positron

Positron decay

Occurs in nuclei which have an excess protons

Nuclear equation

This equations shows how atoms decay

Decay constant

The fractions of atoms which undergo decay per unit time

Half-life

Time taken for half the atoms a radionuclide to undergo radioactive decay

Activity

Number of disintegration of a nucleus occuring per second

Marie Curie

curie(Ci) named after____who discovered and named radium and polonium

Henri Becquerel

Who discovered radioactivity?