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Chemistry: Unit 3
Question | Answer |
---|---|
Johann Dobereiner | found that the properties of certain sets of three elements were very ound that the properties of certain sets of three elements were very similar. He called the set of three elements a triad. |
John Newlands | elements are arranged in order of increasing atomic mass that there is a repetition of their properties every eighth element. This, he called The Law of Octaves. |
Dmitri Mendeleev | responsible for the development of the modern periodic table. He noticed a repetition in the properties of elements as atomic mass increased. |
Henry Moseley | Discovered the atomic number |
Modern Periodic Table | The elements are aligned such that elements with the same number of valence electrons are in the same "A" groups. |
Groups | are the vertical columns of elements. |
Periods | are the horizontal rows of elements. |
Period Numbers | tell you the highest principal quantum number for elements in that period. |
Metals | metallic luster good conductors of heat and electricity malleable, can be pounded into sheets ductile, can be drawn into wires |
Nonmetals | non-lustrous brittle when solid, shatters easily poor conductors of heat and electricity |
Metalloids | properties transitional between metals and non-metals |
Alkali Metals | Group 1 or IA except hydrogen. They are the most reactive metals. |
Alkaline Earth Metals | Group 2 or IIA elements. The second most reactive metals. |
Chalcogens | Group 16 or VIA elements. Also called the Oxygen Family. |
Halogens | Group 17 or VIIA elements. The most reactive nonmetals. |
Noble Gases | Group 18 or VIIIA elements. They are the least reactive elements. |
Magnesium | alloys, especially with aluminum photosynthesis, an Mg atom is found in the chlorophyll molecule Arc welding Fireworks |
Calcium | Bones and teeth |