Electrolytes (Ch 9-6) Alloys (Ch 10-3) Radioactivity (Ch 11-3)

What is an electrolyte? A substance that conducts an electric current when it is dissolved in water. Pure distilled water = not a good conductor. Water + hydrochloric acid = a good conductor. Slightly acidic solutions are good conductors of electricity. Is hydrochloric acid an electrolyte and why? A nonelectrolyte does not conduct an electric current when it is dissolved in water because it does not form ions in solution. Example: solution of sugar Is sugar an electrolyte and why?

What is ionization? The formation of ions when electrolytes are dissolved in water. Electrolytes conduct electricity because they form ions when they dissolve in water. Example: sodium chloride (NaCl) dissolves in water and forms sodium ions (Na+) and chloride ions (Cl-).

What are alloys? Materials made of a mixture of two or more metals. Metals in nature are commonly found in compounds called ores. An ore is a rock or mineral that contains a metal, which can be removed to form a pure metal. Properties of alloys differ from the properties of its separate components. Most alloys are stronger than pure metals. Example: Brass is made up of copper and zinc and is harder than copper and zinc. It is used for water pipes because it lasts longer than either copper or zinc.

What are radioactive elements? Unstable elements whose nucleus breaks down (or decays). Energy and particles are released during this break down/decay. The energy released is radiation. The release of this energy is radioactivity. Recap: What is an isotope? What is a radioactive isotope or radioisotope? Unstable isotope that releases radiation. Example: Carbon-12 and Carbon-13 are stable isotopes. Carbon-14 is unstable and therefore radioactive. Fun fact: Carbon-14 is used in carbon dating which determines the age of certain rocks and fossils.

Nuclear Decay The forces binding the protons and neutrons are unbalanced and causes the atom to split (give off energy). The larger the nucleus of an atom, the more unstable it tends to be. Large atomic nuclei tend to break down to produce radiation. During the process of decay elements may change into other (different) elements. Why do you think this happens?