-
one of the first scientists to design a way of organizing the elements
Dmitri Mendeleev
-
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
Mendeleev
-
what element was named in Mendeleev's honor?
mendelevium
-
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?
Henry Moseley
-
what is the atomic number?
number of protons in an atom of the element
-
disagreement or difference between apparent facts
discrepancy
-
law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements
periodic law
-
what does the periodic table in this book list?
- atomic number
- symbol
- name
- average atomic mass
-
each row of the periodic table
period
-
how many periods does the periodic table have?
7
-
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
group
-
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?
electron arrangement
-
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?
electron arrangement
-
-
process in which atoms may lose or gain valence electrons so that they have a filled outermost orbital
ionization
-
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?
positive ions
-
-
what do group 17 elements form?
negative ions
-
-
how many categories are the 18 groups of the elements further classified?
3
-
what are the 3 categories?
- metals
- nonmetals
- semiconductors
-
in which category are most elements?
metals
-
properties of metals
- shiny solids that can be stretched and shaped
- good conductors of heat and electricity
-
-
which category is found on the right side of the periodic table?
nonmetals, except hydrogen
-
-
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
insulators
-
category of 6 elements that can conduct electricity under certain conditions
semiconductors
-
metalloids
semiconductors
-
examples of semiconductors
-
unit in which one or more groups in the periodic table categorized
family
-
how many families can elements be classified?
5
-
what categorizes a family?
the elements in a family have the same number of valence electrons
-
examples of families of metals
- alkali metals
- alkaline-earth metals
- transition metals
-
which family of metals is very reactive?
alkali metals
-
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
- harder
- denser
- stronger
- have higher melting points than alkali metals
-
how many valence electrons do atoms of alkaline-earth metals have?
2
-
example of alkaline-earth metal
calcium
-
alkaline-earth metals combine with other elements to form ___
compounds
-
lightest of all structural metals
magnesium
-
in which groups are transition metals found?
groups 3-12
-
example of transition metal
gold
-
if an atom of gold loses only one electron, what does it form?
Au+
-
if an atom of gold loses 3 electrons, what does it form?
Au3+
-
properties of transition metals
- harder
- more dense
- higher melting points than alkali and alkaline-earth metals
-
metals that can use the inner shell before using the outer shell to bond
transition metal
-
nuclei of an atom continually decay to produce different elements
radioactive
-
most stable isotope
technetium-99
-
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
promethium-147
-
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
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
halogens
-
how many valence electrons do halogens have?
7
-
how do halogens become stable?
with the addition of a single electron
-
compounds that result from combinations of halogen with other metals
salts
-
how is chlorine used?
to kill bacteria in pools
-
-
a third form of carbon confirmed in 1990
fullerenes
-
most famous fullerene
buckminsterfullerene
-
what kind of atoms (usually in the form of compounds) account for 28% of the Earth's crust?
silicon
-
most abundant element in the universe
hydrogen
|
|
