Ions + Isotopes

• What is an isotope, provide an example from the table in #3?

  An isotope is an element with a different mass due to a different number of neutrons. See Magnesium-25 and Magnesium-26.
• Cation: A positively charged ion that has gained electrons
• Anion: A negatively charged ion
• Isoelectronic: atoms with the same number of electrons or same electronic structure
• Isotope: atoms of the same element but different mass number
• The noble gases have a full outer electron shell so they are very unreactive.
• Metals tend to lose electrons to achieve a stable arrangement
• Non-metals tend to gain electrons for a full outer shell.
• Krypton has an atomic number of 36. List 4 ions isoelectronic to krypton:

  Br- (gains 1 to become stable), Se 2- (gains 2 bc it's easier to gain than lose 6), Rb + (loses 1 to become stable), Sr 2+ (loses 2 to become stable)
• Radiation: act of emitting radiation spontaneously. This is done by an atomic nucleus that, for some reason, is unstable; it "wants" to give up some energy in order to shift to a more stable configuration.
• Carbon dating is a way of seeing the age of organic materials as old as approximately 60,000 years old. It can be used for dating cloth, bone, wood, and plant fibers that humans created in the past.
• Carbon-14 is made when cosmic rays enter the Earth’s atmosphere and collide with an atom in the upper atmosphere, it creates a secondary cosmic ray in the form of an energetic neutron, which collides with nitrogen atoms. The nitrogen atom then turns into a carbon-14 atom and a hydrogen atom.
• Cosmic rays combine with oxygen to form carbon dioxide, which plants absorb. As soon as a living organism dies, it stops taking in new carbon. By looking at the ratio of carbon-12 to carbon-14 in the sample and comparing it to the ratio in a living organism, it’s possible to determine the age of a formerly living thing.
• Half-life is the time needed for the radioactivity of an isotope to have half of its original particles. The half-life of carbon-14 is 5700 years.
• Carbon-14’s half life is short, which is why we can only date back about 60,000 years. Scientists can use other radioactive isotopes that are naturally found in human bodies. For example, Potassium-40 with a half-life of 1.3 billion years or Thorium-232 with a half life of 14 billion years.
• Binary: involving two things
• Binary Ionic Compounds: compound between two ions: cation + anion
• Ionic compound: ions held together by electrostatic forces termed ionic bonding (when two atoms lend/accept one or more electrons between each other)
• Group 1 on Periodic Table: Alkali Metals

  • shiny, silver coloured
  • extremely reactive
• Covalent Bonding: when two atoms share electrons to form molecules
• Group 2: Alkaline Earth Metals

  • fairly reactive, metallic
• Group 7- Halogens

  • most reactive of the non-metals, appear as part of a compound rather than as elements
• Group 8: Noble Gases

  • full valence shells, gases at room temp., non-reactive
• Periods: rows, gradual change from metal to non-metal, number of electrons in valence shell increases.
• Common properties of metals: lustrous, malleable, ductile, conduct electricity, conduct heat.
• Common properties of non-metals: brittle, non-lustrous, non-malleable, don't conduct heat or electricity
• metalloids: between metals and non-metals (staircase)
• In what two ways are neutrons and protons the same?

  Mass of 1 amu, Located in the nucleus
• In what two ways are neutrons and protons different?

  P+: charge of +1, n0: neutral
• In what three ways are protons and electrons different? p+ - in nucleus, mass of 1 amu, positive 1 charge- - in orbitals, mass of essentially nothing (1/2000), negative 1 charge
• 1. Pure substance and mixture

  Pure - matter with the same or constant composition - all particles (atoms/molecules) have the same 

  properties