CHE 106 Lecture Notes - Lecture 7: Dmitri Mendeleev, Alkali Metal, Semimetal
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Isotopes: atoms of same element with different masses (same number of protons, differing neutrons) Fractional abundance: fraction of a sample of atoms that is composed of a particular isotope. Relative abundance: fractional abundance expressed as a percentage. Carbon-12 mass scale: expresses protons, neurons, and electrons as having a respective mass of. Dmitri mendeleev: 1869, arranged elements in order of atomic number, placing them in horizontal rows in such a way that the horizontal columns had similar properties. Periodic table: arranges elements highlighting repletion of properties. Period: elements in horizontal row of periodic table. Group: vertical column; groups typically have similar properties: a groups are main group, b groups are transitional elements, two rows at bottom are inner transition elements. Metal: has a luster, conducts heat and electricity, malleable and ductile. Nonmetal: element that des not exhibit characteristics of a metal. Metalloid: semi-metal , elements having metal and nonmetal properties, good semiconductors. Alkali metals: soft metals that react with water.
