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34 terms

Chapter 4: Elements and the Periodic Table

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atom
the smallest particle of an element
nucleus
tiny region in the center of the atom that has all of the atom's protons and neutrons
protons
positively charged particles in the nucleus
electrons
negatively charged particles that orbit the nucleus
neutrons
particles that have no charge found in the nucleus
energy level
determines the specific amount of energy that an electron has
atomic number
the number of protons in the nucleus of an atom
isotopes
atoms with the same number of protons but different numbers of neutrons
mass number
sum of the protons AND neutrons found in the nucleus of an atom
atomic mass
average mass of all of the isotopes of an element
periods
horizontal row on the periodic table
groups
a vertical column on the periodic table
chemical symbol
a one or two letter symbol used to designate each element
plasma
state of matter that consists of a gas-like mixture of free electrons and nuclei of atoms that have been stripped or electrons
nuclear fusion
process in which two atomic nuclei combine, forming a larger nucleus and releasing large amounts of energy
ductile
the ability to be stretched into 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
when a metal combines with oxygen in the air to weaken the metal (rusting is a form of this)
alkali metals
group 1 elements
alkaline earth metals
group 2 elements
transition metals
the elements in groups 3 thru 12
particle accelerators
move atomic nuclei faster and faster until they have reached very high speeds
nonmetal
element that lacks the properties of a metal
diatomic molecule
consists of two atoms
halogens
the highly reactive group 17 elements
noble gases
the nonreactive group 18 elements
metalloids
elements that have some properties of both metals and nonmetals
semiconductor
can conduct electricity under some conditions but not under other conditions
radioactive decay
the atomic nuclei of unstable isotopes release fast-moving particles and energy
radioactivity
spontaneous emission of radiation by an unstable atomic nucleus.
alpha particle
consists of 2 neutrons and 2 protons and is positively charged; same as a helium nucleus
beta particle
a fast moving electron given off by a nucleus during radioactive decay
gamma radiation
consists of high-energy waves similar to x-rays