Download Patterns of Behavior of Main Group Elements (cont.) Patterns of

Patterns of Behavior
of Main Group Elements (cont.)
Patterns of Behavior
of Main Group Elements (cont.)
• Atomic size is an important factor in the
chemical reactivity of an element.
• Ionic size is also important in determining
how ions behave in solution and the structure
of solid ionic compounds.
Patterns of Behavior
of Main Group Elements (cont.)
Patterns of Behavior
of Main Group Elements (cont.)
• Electrons that are not lost experience a
greater attraction to the nucleus and pull
together in a tighter bundle with a smaller
radius.
• When an electron is added, the charge on the
nucleus is not great enough to hold the
increased number of electrons as closely as it
holds the electrons in the neutral atom.
Patterns of Behavior
of Main Group Elements (cont.)
Patterns of Behavior
of Main Group Elements (cont.)
• Ionic radii decrease because nuclear
charge increases.
• Elements tend to react in ways that allow
them to achieve the configuration of the
nearest noble gas.
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The Main Group Metals
and Nonmetals
The Main Group Metals
and Nonmetals (cont.)
• Group 1 elements are called the alkali
metals.
• Group 2 elements are called the alkaline
earth metals.
– They lose their s valence electron and form
a 1+ ion with the stable electron
configuration of the noble gas in the
preceding period.
– They lose their s valence electrons and
form a 2+ ion with the stable electron
configuration of the noble gas in the
preceding period.
– The most reactive alkali metal is the one
that has the least attraction for this
electron.
– Group 2 elements are less reactive than
group 1 elements because they lose
2 electrons.
The Main Group Metals
and Nonmetals (cont.)
The Main Group Metals
and Nonmetals (cont.)
• Group 17 elements are called halogens.
• Group 18 elements are the noble gases.
– active nonmetals that don’t exist freely in
nature
– Their valence configuration is s2p5.
– no tendency to lose or gain electrons
– lack of reactivity
– form –1 ion with a noble gas configuration
Transition Elements
halogen: an element from group 17 (F, CI, Br, I,
and At) that reacts with metals to form salts
Key Concepts
• In a period of the periodic table, the number of valence
electrons increases as atomic number increases.
• From left to right across a period, atomic radius
decreases. Down a group, atomic radius increases.
• The metal element with the biggest atoms and smallest
number of valence electrons is the most active metal.
• The nonmetal element with the smallest atoms and
greatest number of valence electrons is the most active
nonmetal.
• Transition elements form the d block of the periodic
table.
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Electronegativity—An Attraction
for Electrons
Electronegativity—An Attraction
for Electrons (cont.)
• Electronegativity is a measure of the
ability of an atom in a bond to attract
electrons.
• Electronegativity is a periodic property—it
varies in a predictable pattern across a
period and down a group on the periodic
table.
Electronegativity—An Attraction
for Electrons (cont.)
Electronegativity—An Attraction
for Electrons (cont.)
• Noble gases are considered to have
electronegativity values of zero and do not
follow periodic trends.
• Shielding effect is the tendency for the
electrons in the inner energy levels to block
the attraction of the nucleus for the valence
electrons.
Electronegativity—An Attraction
for Electrons (cont.)
Electronegativity—An Attraction
for Electrons (cont.)
• The farther the bonding atoms are from
each other on the periodic table, the
greater their electronegativity difference.
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