the center of an atom that contains most of the mass of the atom in the form of positive protons and negative neutrons
The positively charged (+) particle in the nucleus which determines what element this is an atom of. Example: 1 Proton is the element Hydrogen.
Russian scientist who discovered a logical pattern in the properties of the elements
the average mass of one atom of the element. The mass averages the common form and the isotopes. It is equal to the mass of the protons and the neutrons.
usually consists of a one or two letter abbreviation of the element name
group or family
elements in a periodic table column that have similar properties and the same amount of valence electrons.
elements in a periodic table row which change properties in a predictable pattern. Each row represents a given amount of energy shells for electrons to be present in.
a type of element that tends to be shiny, hard, malleable, ductile, and a good conductor
a type of element that lacks most of the properties of metals and will bond with metals and non-metals
a type of element that has some of the characteristics of metals and some of the characteristics of nonmetals
made of one kind of matter and has definite properties, may be a single element or a compound
a substance that cannot be broken into smaller pieces
the "smallest piece of matter" that if broken into smaller pieces, loses its original properties
negatively charged particles; move around the outside of the nucleus
the number of protons in an element's nucleus
A table which groups elements into vertical families by number of valence electrons and horizontal periods by the number of energy shells. Each square gives atomic number and mass.
atomic mass unit
special unit used for the mass of a subatomic particle
energy levels or shells
the space around the nucleus in which the electrons travel. Each shell will hold a given number of electrons. 2, 8, 18, 32
The electrons in the energy level that is farthest from the nucleus; that are involved in bonding during chemical reactions.
An atom with the same number of protons and a different number of neutrons from other atoms of the same element
An atom that has taken on or lost electrons to become negatively or positively charged instead of neutral.
electron cloud model
1- a visual model of the most likely locations for electrons in an atom 2- good approximation of how electrons behave in their orbitals
when all the electrons in an atom have the lowest possible energies
a region of space within an energy level or shell where an electron is likely to be found.
Protons, electrons and neutrons of a given element
14 elements with the atomic numbers from 90-103. Most of these are man made and some are radioactive. They are part of period seven and are sometimes called rare earth metals are mostly man-made and radioactive
How readily a substance combines chemically with other substances. Reactivity increases as you go down a the column (group, family) Alkali metals and halogen non-metals are the most reactive elements