The Periodic
Table
Organization, Names, Trends, and Properties
• Elements vary widely in their patterns, but in a very
orderly way.
• Elements in a similar row have similar chemical and
physical properties.
• Dmitri Mendeleev organized the elements based on their
sets of properties.
Periodic Pattern
• The Periodic Law states that when the elements are
arranged according to their atomic numbers, elements
with similar properties appear at regular intervals
The Periodic Law
• Elements in each column have the same number of
electrons in their outer most level.
• These outer most electrons are known as the valence
shell electrons
• These valence electrons are the ones that do all the
reacting and interacting.
Valence Electrons
Page 119 in
your text.
Valence Electrons
• A vertical column on the periodic table is known as a
group
• A horizontal row on the periodic table is known as a
period
• Elements in the same period have the same number of
occupied energy levels.
Arrangement
• Elements in groups 1, 2 and 13-18 are known as the
main-group elements
• The electron configurations of the elements in each main
group are regular and consistent.
• The elements in each group have the same number of
valence electrons
• Ex: elements in group 2 all have two valence e-’s
• ns2, where n is the period number
• The main-group elements are sometime referred to as
representative elements
Main Group Elements
• Elements in Group 1 are called alkali metals
• Name this because they all react with water to make
alkaline (basic) solutions
• Ex: K reacts vigorously with H2O to yield KOH
• Because alkali metals have ________ valence electron(s)
they are __________ reactive.
Alkali Metals
• Group 2 elements are called the alkaline-earth metals
• Also, HIGHLY reactive
• Because they are highly reactive they are usually found as
compounds rather than as pure elements.
• Slightly less reactive than the alkali metals because they
have two electrons to get rid of instead of just one to
achieve the octet rule
Alkaline-Earth Metals
• Elements in Group 17 are known as the halogens
• The halogens are the MOST reactive group of nonmetal
elements because they are soooo close to achieving their
octet (they have to STEAL one electron)
• React with most metals to form salts
• In fact, the name halogen is Greek for “salt maker.”
Halogens
• Group 18 elements are known as the noble gases
• They HAVE their octet achieved already (8 valence
electrons)
• Soooooo, are they reactive????
• It is the full outer shell than lead scientists to believe 8
was nonreactive, not the other way around
Noble Gases
• Hydrogen is in a class all by itself
• It is the MOST COMMON element in the universe
• Roughly 3 out of every 4 atoms in the universe is H
• Hydrogen has _________ electron(s) but wants _______.
• Does not follow the ______________ rule
Hydrogen is Special
• Most elements are metals
• All metals are excellent conductors of electricity
• Great conductors of heat
• Ductile (can be squeezed into a wire) and malleable (can be
pounded into shape)
• Alloys are mixtures of elements, giving them a mixture of
properties  eliminate bad properties and give the good ones.
Metals
• Transition Metals are groups 3–12 (we know them as??)
• Sometimes called the d-block b/c of their position
• DO NOT have the same number of valence electrons
• This causes the varying charges
• May lose or gain DIFFERENT numbers of electrons
depending on who its bonding with (again, explaining the
varying charges)
• Also good conductors or heat / electricity
Transition Metals
• Lanthanides and Actinides
• Lanthanides - Shiny metals similar in reactivity to the
alkaline-earth metals
• Actinides – Nuclei are unstable, making all of them
radioactive. The best known actinide is U, or
_______________.
f - Block
• Ionization Energy – the energy required to remove an
electron from an atom or ion. (Decreases down and to the
left)
Decreases
Decreases
Periodic Trends (page 134-135)
• Electron Shielding blocks the outer electrons from the
inner nucleus attraction, making them less tightly held.
• Bond Radius – half the distance from center to center of
two like atoms that are bonded together.
• Atomic radius increases bottom to top and to the left to
right.
Periodic Trends (page 134-135)
• Electronegativity – a measure of the ability of an atom in a
chemical compound to attract electrons
• Decreases as you move down a group
Decreases
Decreases
Electronegativity