Atomic Theory, Isotopes, and Radioactive Decay 7.1 Atomic Theory, Isotopes, and Radioactive Decay

Today’s lesson Atomic structure Subatomic particles Atomic forces Isotopes Radioactive decay Homework: Text: Chapter 7, pages 286-301 Workbook: Chapter 7, pages 120- 128

The Atom Fill out the diagram below using the word bank on the right Nucleus Electron shells Protons Valence shell Neutrons Electrons

Properties of Subatomic Particles Charge Mass (amu) Location A change in number results in a Determines Proton   Electron Neutron

Stability Stability refers to whether or not the atom will break apart into smaller pieces Why would an atom break apart? + + + -

Forces in an atom Electromagnetic force Strong nuclear force Oppositely charges attract Like charges repel Charged particles attract neutral particles Force responsible for ______________________________ Strong nuclear force Binds neutrons and protons together to form the nucleus Responsible for Weak nuclear force Stabilize atoms Can cause ____________________________ Gravitational force Force of ______________________________ Proportional to mass so it is weak in an atom

What trend do you see between expected mass and periodic mass? Atom Number of Protons Number of Electrons Number of Neutrons Expected Mass Periodic Table Mass H He C Ne K Cu I What trend do you see between expected mass and periodic mass? Why are the masses on the periodic table decimal values?

Isotopes Elements can exist in various isotopes Different isotopes will have the same number of protons and electrons but different numbers of neutrons Example: Carbon Carbon is found in three naturally occurring isotopes ______________________________________________________________ ______________________________________________________________

Calculating periodic table masses The mass on a periodic table takes into account the masses of the different isotopes and their relative abundance Stability influences abundance, unstable particles won’t exist long in the form Example: Carbon General formula: ________________________________________________________

Radioactivity Unstable particles split apart, releasing smaller particles and energy RADIOACTIVITY: the emission of energy or particles caused by the spontaneous disintegration of atomic nuclei Radioactive decay: the process in which unstable nuclei lose energy by emitting radiation in the form of particles and energy

Three main types of radioactive decay Alpha decay Beta decay Gamma decay Releases energy } Release particles (and energy)

Alpha decay The emission of an alpha particle (helium nuclei) from a nucleus __________________________________________________________

Beta decay Beta decay: when a neutron changes into a proton, which stays in the nucleus, and a high-energy electron ____________________________________________________ _

Gamma radiation Gamma decay: a high-energy gamma ray given off as an isotope falls from a high-energy state to a low-energy state _______________ ________________________________________________________ _ ________________________________________________________

Electromagnetic spectrum The energy released from a radioactive source takes the form of waves Depending on the amount of energy released, the waves will have various wavelengths The different wavelengths form the electromagnetic spectrum

Today’s lesson Atomic structure Subatomic particles Atomic forces Neutrons role in stability Atomic forces Electromagnetic Strong nuclear Weak nuclear Gravitational 4. Isotopes Definition/representing Calculating the periodic table mass 5. Radioactive decay Definition Alpha Beta Electromagnetic spectrum Gamma

Next lesson Half-life Carbon-dating