Download Matter: Building Blocks of the Universe Chapter 5 Classification of

Matter: Building Blocks of the Universe
Chapter 5
Classification of Elements
A. Highlights for Section 1 pages 107-112
 Russian chemist Dmitri Mendeleev made first scientific attempt to
classify elements: organizing them in order of increasing atomic mass
 British scientist Henry Moseley arranged the elements in order of
increasing atomic numbers in a periodic table
 Basis of the periodic table is the periodic law—The physical and
chemical properties of the elements are periodic functions of their
atomic numbers
F. Highlights for Section 2 pages 112-121
 Each vertical column is numbered—columns of elements are called groups
or families
o Elements within the same family have similar but not identical
properties
 Each horizontal row of elements is called a period
o Elements in a period are not alike in properties
 Each element is given a separate square—contains atomic number, atomic
mass, chemical symbol, and name
 Dark zipzag line run down right side of periodic table
o 88 elements on left side of this line—metals—physical properties are
luster, good conduction of heat and electricity, high melting point,
ductilitiy (can draw into thin wires), malleability (can hammer into
thin sheets)
o Metals tend to lose their outermost electrons when they combine
chemically
o Nonmetals are located to the right of zipzag line—physical and
chemical properties are opposite of the metal properties
 Left to right across a period atomic size tends to decrease
o As the atomic number increases across a period, 1 electron is added
to each element
o This electron is still in the same energy level
o Increase in number of electrons in an energy level and number of
protons in the nucleus produces a stronger reaction or attraction
between these oppositely charged particles
o Electrons are pulled closer to the nucleus
o Size of the atom decreases
 Metallic properties—elements become less metallic as they go left-right
across a period
O. Highlights for Section 3 pages 122-130
 Elements within the same family have similar properties because they have
the same number of valence electrons
 Family 1—Alkali—soft, silver, white, shiny—react or combine with other
elements easily—never found alone in nature
 Family 2—Alkaline—Earth metals—very reactive
 Between Family 2 and 13 are the transition metals—these are the metals
you are most familiar with
 Family 13 is the Boron family
 The Carbon family is #14—Carbon atoms form an endless number of
different compounds—more than 5,000,000
 Family 15 is the Nitrogen family
 Family 16 is the Oxygen family
 Family 17 is the Halogen family—most active nonmetals
 Rare Earth elements are found in the two bottom rows of the periodic
table
o First row Lanthanide series—made up of soft malleable metals. Have
high luster and conductivity
o Second row is the Actinide series—all of the elements are
radioactive—most are synthetic—made in a lab
AA. Highlights for Section 4 pages 131-133
 Family or group
 Left side of periodic table—metals
 Right side of periodic table—nonmetals
 Metalloids—metals and nonmetals—zigzag line
 Period—rows
 Properties of elements: electron arrangement, reactivity, atomic size,
metallic properties
 Valence number—number of electrons in the outermost shell—chemical
combining takes place here
 Element with a valence of 1 will gain, lost, share 1 electron in chemical
combination
 Elements at the left of a period tend to lose electrons easily when they
combine with other elements
o Elements at right of a period tend to gain electrons easily when they
combine with other elements
 Amount of energy needed to remove an electron from an atom shows a
periodic increase from left to right across a period
 Left to right across a period atomic size tends to decrease
o As the atomic number increases across a period, 1 electron is added
to each element
o This electron is still in the same energy level
o Increase in number of electrons in energy level and number of
protons in nucleus produces a stronger attraction between these
oppositely charged particles
o Electrons pulled closer to nucleus
o Size of atom decreases
 Metallic properties—elements become less metallic as they move left-right
across a period