Organizing Elements ** You need to add what is in RED to your notes
Mendeleev • He noticed that some elements had similar chemical and physical properties. • He wrote each elements name and known information on cards and tried various arrangements. • He realized that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass. • He then predicted the properties of elements that would later be discovered.
The modern Periodic table • Periodic- In a regular, repeated pattern. • In 1913 Mosley discovered how to measure the number of protons in an atom. • Shortly after the table was rearranged in order of atomic number. • This caused some elements to shift position and the patterns of properties to become more regular.
Organization of Periodic Table • The properties of an element can be predicted from its location in the periodic table. • Periods- The rows in the periodic table. • As you move across a period, the elements’ properties change in a predictable way. • Ex: Reactivity, metals, nonmetals, gas. • Groups- The columns in the periodic table. • Also known as families. • The elements in each group have similar characteristics. • Ex: All elements in Group 1 react violently with water. The elements in Group 18 rarely react at all. The elements in the same group have the same number of valence electrons
Metals • Physical Properties- • Shininess • Malleability- material can be hammered or rolled into sheets. • Ex: • Ductility- Material can be pulled out into a long wire. • Ex: • Conductivity- The ability of a material to transfer heat or electricity. • Ex: • Others include: Color, Magnetism, and State.
Metals • Chemical Properties- • Reactivity- The ease and speed that an element combines, or reacts, with other elements. • Ex: • Sodium Reacting in water • Corrosion- the slow combination of a substance with oxygen. Iron rusting.
Alkali Metals • Group 1 • Key Properties: • Soft • React Violently • Low Melting Point • Low Density • Never found uncombined in nature • Have 1 valence electron and like to give it away
Alkaline Earth Metals • Group 2 • Key Properties: • Shiny grey-white • Relatively high melting and boiling points • Good conductors • Tarnish quickly when exposed to air • Never found uncombined in nature • Have 2 valence electrons that they need to give away
Transition Metals • Groups 3 through 12 • Key Properties: • Hard • Shiny • Good conductors of electricity. • Not very reactive
Lanthanides • Top row of elements grouped below the table. • Key properties: • Soft, Malleable, Shiny, High Conductivity. Actinides • Bottom row of elements grouped below the table. • Key properties: • Only Ac, Th, Pa, and U occur naturally. • The rest are synthetic.
Metals in Mixed groups • Some of the elements in Groups 13 through 15 are metals. • Ex: Aluminum, Tin. Synthetic Elements • Elements with an atomic number higher than 92. • They are not found naturally on earth. • They are made –or synthesized- when nuclear particles are forced to crash into one another. • Scientist use a Particle Accelerator to cause this.
Nonmetals • An element that lacks most of the properties of a metal. All of the yellow elements on the periodic table in class are Nonmetals. • Key Properties: Physical: • Poor conductors of electricity and heat. • 10 of the 16 nonmetals are gases. • Solid nonmetals are dull (not shiny) and brittle (not malleable or ductile). • Lower densities Chemical: • Most are reactive.
Carbon Family • Group 14 • A mixed group • Carbon- All organisms are made from carbon compounds. • Have 4 valence electrons. They need to add or remove 4. Nitrogen Family • Group 15 • A mixed group • The atmosphere is 80% Nitrogen. • Have 5 valence electrons. They need 3.
Oxygen Family • Group 16 • A mixed group • Oxygen and Sulfur are the most common elements in the family. • Have 6 valence electrons. They need 2. Halogen Family • Group 17 • The word Halogen means “salt forming” • 4 of the 5 are Nonmetals. Astatine is a Metalloid. • Most reactive Nonmetals • Have 7 valence electrons. They need 1.
Diatomic Molecules • Consist of two atoms. • The seven diatomic elements are: • Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, and Iodine. • 7TH Heaven Noble Gases • Group 18 • VERY stable. • They do not ordinarily form compounds. • Have a complete shell of valence electrons. They need 0.
Hydrogen • The simplest and smallest atom. • 1 proton, 1 electron. • Not grouped into any family because its properties are so different. • Make ups 90% of the atoms in the universe, but only 1% of the mass of the earth’s crust, oceans, and atmosphere. • Rarely found uncombined on earth. Most is combined with oxygen in H2O. • Most is located in stars and gas planets in the plasma state. • Has 1 valence electrons. It only needs 1 more to complete the first shell that can only hold 2 electrons. Most often shares.
Metalloids • Seven elements that are found along the “stairs” on the periodic table. The pink elements on the periodic table in class. • Have some characteristics of both metals and nonmetals. • Solid, brittle, hard, somewhat reactive • Are semiconductors • Substance that can conduct electricity under some conditions but not under other conditions. • Used to make computer chips, and lasers.