Radioactivity and Nuclear DecayName/Block

Chapter 9, Section 1___Ima Student___

The atom is composed of three types of particles. They are the __proton__ that has a (+, -- , ø ) charge, a _neutron_ that has a (+, -- , ø ) charge, and a _electron__ that has a(+, -- , ø ) charge.

The protons electrically attracted to the _electron__. The two particles that are found in the nucleus are the __proton__ and the __neutron__. The __electrons___ are found “orbiting” the nucleus. Almost all of the mass of the atom is found in the nucleus.

Protons are (attracted to , repulsed by) other protons. The force that holds protons together in the nucleus is the ______strong nuclear force______. This force will hold protons together with (protons, protons and neutrons, all particles). This force will work over (short distances, long distances, any distance).

The electromagnetic force will work over (short distances, long distances, any distance). The (electric , strong nuclear) force is more powerful than the (electric , strong nuclear).

An unstable atom will (burn quickly , break apart , mix with other atoms). All atoms with more than _82_ protons will be unstable. Another name for unstable is (radioactive , isotope , unchanging). The “biggest” element that exists naturally on Earth is (Thorium , Uranium , Americium).

The number of protons is called the (mass number , atomic number , electric number), and the number of protons AND neutrons is the (mass number , atomic number , electric number).

Atomic nuclei that have the same number of protons, but different numbers of neutrons are called (carbon , isotopes , ions , atoms). The isotope C-14 has six (protons , neutrons) and eight (protons , neutrons). It would also have (6 , 8 , 14) electrons.

Radioactivity was discovered by ___Henri Becquerel___. Marie and Pierre Curie discovered polonium and radium.

Strong ForceAtomic

ParticleChargeLocationAttraction mass or number

ProtonPositiveNucleusYes1

NeutronNeutralNucleusYes1

ElectronNegativeEdge ofNozero

atom

Most elements exist in nature as isotopes. Isotopes of an element are almost identical in their chemical properties and reactions. However, the nuclear properties are different. Not only do isotopes differ in mass, but some may also be radioactive. Using the periodic table in the back of your book, complete the information in the chart below.

SymbolAtomicNumber ofNumber ofMass

NumberProtonsNeutronsNumberName

(given)

H-11 (per tab)1 (# of pro)(1-1) = 01 (1+0)Hydrogen

H-2

H-3

He-4

C-12

C-14

O-18

Sc-49

Co-63

Pb-212

Ra-222

Ra-226

U-235

U-238