The Periodic Table
Alkali metals Highly reactive metals
in group 1A of the periodic table
Alkaline earth metals Fairly
reactive metals in group 2A of the periodic
table
Transition metals Those elements
found in the d block of the periodic table
whose properties tend to be less
predictable based simply on their position
in the table
Halogens families Highly
reactive nonmetals in group 7A of
the periodic table
Noble gases The group 8A
elements, which are largely
unreactive (inert) due to their stable
filled p orbitals
The Periodic Table
Atomic radii A measure of the size of an atom
Ionic radii A measure of the size of an atoms ion in a crystal lattice form
Electronegativity The ability of an atom to attract electrons to itself
Ionization energy The energy required to remove an electron from an atom or ion in its gaseous state
Knowing the Periodic Table
Rows are referred to as periods
Columns are referred to as families or groups
Elements within a group generally have similar properties
When elements are arranged in order of increasing atomic number, there are recurring physical and chemical properties Periodic law
States of Matter at Room Temperature
Development of the Periodic Table
The number of known elements drastically increased in the early 1800s
In 1869, Dmitri Mendeleev from Russia and Lothar Meyer form Germany published classification systems
Mendeleev is given credit for organizing elements into the periodic table
Development Cont.
The periodic table is an arrangement of elements in which they are separated into groups based on repeating properties
Mendeleev arranged the elements in order of increasing mass (there were some exceptions Ex. Te and I)
It was later realized that arranging by properties, rather than mass was more accurate
Mendeleev left gaps for undiscovered elements, but accurately predicted their properties
Modern Periodic TableIn the early 1900’s Henry Moseley determine atomic numbers of each known element
The modern table is arranged based on increasing atomic numbers
Each period on the periodic table corresponds to a principal energy level
Elements with similar chemical and physical properties end up in the same column
Main Chemical Families
Alkali Metals
Alkaline Earth Metals
Transition Metals
Halogens
Noble gases
Properties of Alkali Metals (Group 1)
Have metallic properties of metalsShiny luster, malleability, high thermal and electrical conductivity
Soft solids at room temperature, low melting points and densities
Very reactive! (Especially with water)
Found as compounds in nature, never as free elements
Lose an electron when they react, thus have a +1 oxidation state
Properties of Alkaline Earth Metals (Group 2)
Soft metals
Very reactive! (Less reactive than alkali metals)
All except beryllium (Be) react with water
Most occur naturally only in compounds
When reacted, they give up 2 electrons and have a +2 oxidation state
Properties of Transition Metals (Groups 3-12)
Most transition metals have common metallic characteristics with other elements in their families ; except zinc (Zn), cadmium (Cd), and mercury (Hg)
Can exist in several common oxidation states
Are likely to form complexes with unbalanced charges and excessive electrons
Properties of Halogens (Group 17)
All halogens are nonmetals
Generally poor conductors of heat and electricity
Are not all found in the same state of matterThe only family with all 3 states of matter
At room temperature, fluorine (F) and chlorine (Cl) are gases. Bromine (Br) is a liquid. Iodine (I) and astatine (At) are solids.
Very reactive (will even react with glass!)
Halogens are commonly found as diatomic molecules (F2, Cl2)
Gain an electron when reacted; oxidation state of -1
Properties of Noble Gases
All gases at room temperature
Odorless and colorless
Very low reactivity
Exist as unbound elements in nature
Referred to as inert (nonreactive)
Trends of Atomic Radii
Size of atoms is expressed as the atomic radius
Atomic radii generally decrease from left to right across a period and increase from top to bottom of a group
Principal quantum number (n) of outer-level electrons increases by one from period to period
Ex. Elements in period 1, n=1. For period 2, n=2, and so onAs n increases down a family, the average position of outer-level electrons is farther from the nucleus
As a result, atoms are LARGER
Trends of Ionic RadiiIon atom or group of atoms with a charge
Cation atoms that have lost 1 or more e- and have a + charge
Cations are smaller in radius because they have lost e-
Ex. Ca2+ is smaller than Ca because it has lost 2 e-
Anion atoms that have gained 1 or more e-
Anions are larger because they have gained e-
Ex. Br- is larger than Br because it has one more e- orbiting
Trends of anions and cations are similar to that of their neutral atomic radii
Electronegativity TrendNumber of protons and the principal
quantum number influence electronegativity
Generally, electronegativity increases from left to right across a period (because the # of p+ increases)
It generally decreases from top to bottom of a group (due to outer energy level e- being farther from the nucleus
Ionization Energy TrendIn the event of multiple e- being removed
from an atom, there are different ionization energies corresponding to each e- removed
The energy required to remove the first e- is referred to as the “first ionization energy”
Generally, ionization energy increases from left to right across a period and decreases from top to bottom within a family
Ionization Energy Cont.
Depends on the force of attraction the nucleus exerts on the e-
Also depends on # of p+ and distance of e- from the nucleus
The more p+ force, the more difficult to remove an e-
Atomic Radii Practice
Arrange the following elements in order of increasing atomic radii
SodiumIronPotassiumSulfurPhosphorus
Ionic Radii Practice
Arrange the following ion in decreasing order of ionic radii
Mg2+
F-
Cu2+
Li+
O-
Electronegativity Practice
Which of the following atoms is more electronegative? Which is less?
CalciumChlorine
Explain why you chose ___ as more electronegative than ___.
Ionizing Energy Practice
Do metals or non-metals have a higher ionizing energy?
List the following elements in order of increasing ionizing energy
AuCoPd