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8-Science Vocab 1.3
8th grade science vocab
Term | Definition |
---|---|
Reactive | Indicates how likely an element WILL undergo a chemical CHANGE. |
Metal | Elements that are GOOD CONDUCTORS OF ELECTRICITY and HEAT well and have a SHINY appearance; can be shaped easily by hammering/pounding or bending or drawn into a long wire; are solid at room temperature. |
Nonmetal | Elements on the right side of the periodic table; most are GASES and have dull surfaces and cannot be shaped by hammering; they are POOR CONDUCTORS of heat and electric current. |
Metalloid | Elements that have properties of BOTH METALS AND NONMETALS. Silicon is a metalloid. They are on either side of a zigzag line on the periodic table. |
Radioactivity | The process by which atoms PRODUCE ENERGY and particles. |
half-life | The time it takes for one-half (½) of atoms in a sample to decay. Ex.: 1000 samples = 500 atoms with half life. |
Alloy | A substance made of TWO or MORE METALS MELTED TOGETHER; a mixture of metals. |
Lanthanide | A series of the 15 METALLIC ELEMENTS with INCREASING atomic numbers from 57 to 71 and beginning with lanthanide through lutetium. |
Halogen | A group of 5 elements consisting of fluorine, chlorine, bromine, iodine, and astatine. |
Noble gas | A group of 7 RARE GASES that include helium, neon, argon, krypton, xenon, and usually radon. |
Semiconductor | A material that is NEITHER A GOOD CONDUCTOR NOR a GOOD INSULATOR but conducts electricity when heat or light is added. |
Radioactive decay | A process by which a radioactive isotope LOSES SUBATOMIC PARTICLES particles or energy by emitting radiation. |