27 terms

Hug PH CIA Chapter 4 Vocab.

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Nucleus
the center of an atom that contains most of the mass of the atom in the form of positive protons and negative neutrons
Proton
The positively charged (+) particle in the nucleus which determines what element this is an atom of. Example: 1 Proton is the element Hydrogen.
Dmitri Mendeleev
Russian scientist who discovered a logical pattern in the properties of the elements
atomic mass
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.
chemical symbol
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.
period
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.
metal
a type of element that tends to be shiny, hard, malleable, ductile, and a good conductor
nonmetal
a type of element that lacks most of the properties of metals and will bond with metals and non-metals
metalloid
a type of element that has some of the characteristics of metals and some of the characteristics of nonmetals
pure substance
made of one kind of matter and has definite properties, may be a single element or a compound
elements
a substance that cannot be broken into smaller pieces
atom
the "smallest piece of matter" that if broken into smaller pieces, loses its original properties
electrons
negatively charged particles; move around the outside of the nucleus
atomic number
the number of protons in an element's nucleus
periodic table
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
valence electrons
The electrons in the energy level that is farthest from the nucleus; that are involved in bonding during chemical reactions.
Isotope
An atom with the same number of protons and a different number of neutrons from other atoms of the same element
ion
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
ground state
when all the electrons in
an atom have the lowest
possible energies
orbital
a region of space within an energy level or shell where an electron is likely to be found.
PEN
Protons, electrons and neutrons of a given element
actinides
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
reactivity
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