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29 terms

Elements and the Periodic Table

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nucleus
The central core of an atom containing protons and usually neutrons.
proton
A small, positively charged particle in the nucleus of the atom.
neutron
A small particle in the nucleus of the atom, with no electrical charge.
electron
A tiny negatively charged particle that moves around the nucleus of an atom.
atomic number
The number of protons in the nucleus of an atom.
isotope
An atom with the same number of protons and a different number of neutrons from other atoms of the same element.
mass number
The sum of protons and neutrons in the nucleus of an atom.
atomic mass
The average mass of all the isotopes of an element.
Periodic Table
A chart of the elements showing the repeating pattern of their properties.
chemical symbol
A one- or two- letter representation of an element.
period
A horizontal row of elements in the periodic table.
group
Elements in the same vertical column of the periodic table; also called family.
metal
A aclass of elements characterized by physical properties that include shininess, malleability, ductility and conductivity.
malleable
A term used to describe material that can be pounded into shapes.
ductile
A term used to describe a material that can be pulled out into a long wire.
conductivity
The ability of an object to transfer heat or electricity to another object.
reactivity
The ease and speed with which an element combines or reacts with other elements and compounds.
corrosion
The gradual wearing away of a metal element due to its chemical reaction.
alkali metal
An element in Group 1 of the periodic table.
alkaline earth metal
An element in Group 2 of the periodic table.
transition metal
One of the elements in Groups 3 through 12 of the periodic table.
alloy
A mixture of two or more elements one of which is a metal.
particle accelerator
A machine that moves atomic nuclei at higher and higher speeds until they crash into one another, sometimes forming heavier elements.
nonmetal
An element that lacks most of the properties of a metal.
diatomic molecule
A molecule consisting of two atoms.
haologen
An element found in Group 17 of the periodic table.
noble gas
An element in Group 18 of the Periodic Table.
metalloid
An element that has some characteristics of both metals and nonmetals.
semiconductor
A substance that can conduct electricity under some conditions.