RPC prelim t1

ATOM

• Smallest unit into which chemical element can be broken down without losing its  chemical identity. 

ionized

If an atom has an extra electron or has had an electron removed

Nucleons

is the number of protons and  neutrons

electron binding energy.

The work that is required to remove an electron from an atom

511 keV.

Rest mass energy of an electron

1.007276

Protons has an atomic mass unit of _______

 1.008665

Neutrons has an atomic mass unit of _________

1 amu

Protons and neutrons have a mass of approximately ______

0.000545 amu or zero amu

Electrons have a much smaller mass of ___________

Democritus of Adbera (northern Greece)

 asserted that all material things are composed  of extremely small irreducible particles called atoms. 

atomos

it means indivisible in greek terms

ARISTOTLE

one of the most influential people of his time, described all matter as being composed  of the "four basic elements" fire, earth, air and water. 

 JOHN DALTON (1803)

• Proposed an "atomic theory" with spherical solid atoms based upon measurable  properties of mass.  

• The Hook and Eye Model 

JOSEPH JOHN THOMSON (1897) 

• Plum pudding model 

• He thought that atoms were not indivisible spheres, but positive spheres with negative  electrons embedded in them.

ERNST RUTHERFORD (1899) 

Studied the deflection of alpha particles as they were targeted at thin gold foil sheets.

proposed the name "proton" for the positively charged particles in the  nucleus of an atom. 

 JAMES CHADWICK (1932)

Proved the existence of neutrons, neutral particles in the nucleus that made up  approximately half the mass of an atom. 

NIELS HENRIK DAVID BOHR

In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons  can have stable orbits around the nucleus.

Bohr’s model states that the electrons move in orbits of fixed size and energy.

STRONG FORCE

• Also known as Nuclear Force 

• is very strong, but very short-ranged. It acts only over ranges of order 10^-13 centimeters and is  responsible for holding the nuclei of atoms together.  

• It is basically attractive but can be effectively repulsive in some circumstances.

• Strong forces hold the nucleus togethe

ELECTROMAGNETIC FORCE/ ELECTROSTATIC FORCE

• causes electric and magnetic effects such as the repulsion between like electrical  charges or the interaction of bar magnets.  

• It is long ranged, but much weaker than the strong force. 

WEAK FORCE  

• responsible for radioactive decay and neutrino interactions.  

• Weak forces are involved in beta decay. 

Issac Newton

who discovered that every particle in the universe attracts another particle  with some force.

gravitational force. 

That force of attraction is called