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Based on increasing atomic weights and arranged so elements with similar properties were in the same column.
How the was the periodic table arranged?
Rearranged the periodic table in order of atomic number; determined the number of positive charges in the nucleus - became the concept of atomic number
Equal to the number of protons in the nucleus, as well as the number of electrons in the electron cloud
Weighted average of the masses of all the element's isotopes. Rounding the atomic mass to the nearest whole number yields the mass number of the most common isotope
Similar to Bohr's model where the electrons orbit around the nucleus in circular orbits.
Chemical Properties of Metals
Corrode Easily. Corrosion is a gradual reaction with substances in the air. It results in the loss of the element.
Physical Properties of Metalloids
Conduct heat and electricity better than nonmetals but not as well as metals
1st Column of periodic table; Extremely reactive solids - never found uncombined in nature , must be stored under oil to keep them from reacting with the air; 1 valence electron
Alkaline Earth Metals
2nd column of the periodic table; slightly less active than Alkali Metals - still highly reactive; Like the Alkali Metals most need to be stored under oil; not found free in nature; 2 valence electrons
Middle block; Properties are similar to one another and other metals, but different from other elements; form brightly colored compounds used in paint and ceramic glaze pigments; valance electrons vary but most have 1-3
Highly reactive; Chlorine and fluorine are gases; bromine is a liquid; iodine and astatine are solids; iodine undergoes sublimation from a solid to a gas; 7 valence electrons
Non-reactive; all are gases and are found in small amounts in the atmosphere; 8 valence electrons (Helium has 2)
Shiny and silvery-white; tarnish easily when exposed to air; react violently with most nonmetals; relatively soft; located at the bottom of the table
All elements past Uranium (92) are synthetic - made in a lab; Most are radioactive - unstable nuclei
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