Unit 5 test
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Unit 5 test
organizing the elements
one of the first scientists to design a way of organizing the elements
how did Dmitri Mendeleev list the elements?
by increasing atomic mass
when was the first periodic table of the elements published?
1869 by Mendeleev
what did question marks and/or gaps indicate in Mendeleev's periodic table?
predicted new elements that would be discovered
considered the father of the periodic table
what element was named in Mendeleev's honor?
what was wrong with Mendeleev's periodic table?
some elements did not quite fit the pattern - elements' similar properties did not appear at regular intervals
who arranged the elements by atomic number rather than by atomic mass?
what is the atomic number?
number of protons in an atom of the element
disagreement or difference between apparent facts
law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements
what does the periodic table in this book list?
average atomic mass
each row of the periodic table
how many periods does the periodic table have?
what happens as you move from left to right across a period?
properties such as reactivity and conductivity change and elements become less metallic
each column of the periodic table
what similarities do elements in each group have?
similar chemical properties
what are chemical properties related to in each element?
number of electrons
for a neutral atom, the number of protons equals?
number of electrons
the periodic trends in the periodic table are the result of what?
by what are the chemical properties of each group largely determined?
number of valence electrons
where are the valence electrons located?
closest to the outside of the atom and are sometimes considered part of an outer "shell" of electrons
what determines many of the chemical properties of an element?
the number of valence electrons
an element's location in the periodic table is related to what?
a charged atom
process in which atoms may lose or gain valence electrons so that they have a filled outermost orbital
what happens if an atom gains or loses electrons?
it no longer has an equal number of electrons and protons
what happens when an atom no longer has an equal number of electrons and protons, and the charges do not cancel completely?
the atom has a net electric charge
what do group 1 elements form?
what do group 17 elements form?
how many categories are the 18 groups of the elements further classified?
what are the 3 categories?
in which category are most elements?
properties of metals
shiny solids that can be stretched and shaped
good conductors of heat and electricity
examples of metals
which category is found on the right side of the periodic table?
nonmetals, except hydrogen
examples of nonmetals
properties of nonmetals
may be solids, liquids or gases at room temperature
solids are often dull and brittle
poor conductors of heat and electricity
materials that do not conduct heat or electricity well
category of 6 elements that can conduct electricity under certain conditions
examples of semiconductors
unit in which one or more groups in the periodic table categorized
how many families can elements be classified?
what categorizes a family?
the elements in a family have the same number of valence electrons
examples of families of metals
which family of metals is very reactive?
why is an atom of an alkali metal very reactive?
it has one valence electron that can easily be removed to form a positive ion
properties of alkaline-earth metals
have higher melting points than alkali metals
how many valence electrons do atoms of alkaline-earth metals have?
example of alkaline-earth metal
alkaline-earth metals combine with other elements to form ___
lightest of all structural metals
in which groups are transition metals found?
example of transition metal
if an atom of gold loses only one electron, what does it form?
if an atom of gold loses 3 electrons, what does it form?
properties of transition metals
higher melting points than alkali and alkaline-earth metals
metals that can use the inner shell before using the outer shell to bond
nuclei of an atom continually decay to produce different elements
most stable isotope
what is technetium-99 used for?
to diagnose cancer as well as other medical problems that occur in soft tissues of the body
most useful isotope
where are tiny amounts of americium-241 found?
most household smoke detectors
families of nonmetals include?
one of the elements of group 18 of the periodic table
example of noble gas
how do noble gases exist?
as single atoms instead of as molecules
because of the unreactivity of noble gases, what happens with electrons?
noble gases do not gain or lose electrons to form ions
most do not join with other atoms to form compounds
how is helium used?
used to give lifts to blimps and balloons
how is argon used?
to fill light bulbs because its lack of reactivity prevents the bulbs' filaments from burning
most reactive nonmetals
how many valence electrons do halogens have?
how do halogens become stable?
with the addition of a single electron
compounds that result from combinations of halogen with other metals
how is chlorine used?
to kill bacteria in pools
a third form of carbon confirmed in 1990
most famous fullerene
what kind of atoms (usually in the form of compounds) account for 28% of the Earth's crust?
most abundant element in the universe