Chapter 6: The Periodic Table

6.1: Development of the Modern Periodic Table

Antoine Lavoisier

• Late 1700’s• 33 elements (known at time) organized in four

categoriesCategory Elements (Old English Names)

Gases Light, heat, dephlogisticated air, phlogisticated gas, inflammable air

Metals Antimony, silver, arsenic, bismuth, cobalt, copper, tin, iron, manganese, mercury, molybdena, nickel, gold, platina, lead, tungsten, zinc

Nonmetals Sulphur, phosphorus, pure charcoal, radical muriatique, radical fluorique, radical boracique

Earths Chalk, magnesia, barote, clay, siliceous earth

Lothar Meyer/Dmitri Mendeleev

• Mid-late 1800’s• Demonstrated a connection between atomic

mass and elemental properties• Arranged elements with similar chemical

properties horizontally• Mendeleev is given more credit because he

published first

Henry Moseley

• Early 1900’s• Realized arranging the elements by atomic mass

was not the best way – some elements ended up in columns with elements of different properties

• Discovered atoms have a unique number of protons (the atomic number)

• Arranged elements in order of increasing atomic number, which resulted in a periodic pattern of properties

Modern Periodic Table

• Groups/Families = vertical columns• Periods = horizontal rows

(Z)

Metalloids – along step line (except for Aluminum)

Properties of Metals

• Conduct heat and electricity• Malleable (can be hammered into thin sheets)• Ductility (can be pulled into wires)• Lustrous (shiny) appearance

• Almost all metals are solids at normal temperatures

Properties of Non-Metals

• Generally lack properties that characterize metals

• Show more variation in properties than metals do

• Many are gaseous at normal temperatures

CLASSIFICATION OF THE ELEMENTSSection 6.2

6.2: Organizing the Elements byElectron Configuration

• Valence electrons– Electrons in the outermost principal energy level– Number of valence electrons correspond to the

representative elements group number (Group 1 has 1 valence electron, Group 2 has 2 valence electrons, Group 13 has 3 because it is the 3rd representative group, etc)

– Energy level of valence electrons correspond to the period number (Period 4 valence electrons are in the 4th energy level and so on…)

The s-, p-, d-, and f-Block Elements

• We saw these with our little “cheat sheets”• This shows which sublevel is being filled

PERIODIC TRENDSSection 6.3

PERIODIC TREND QUIZ

1)What group is the:– Noble Gases– Alkali Metals– Halogens– Transition Metals2)Identify the # of valence electrons for each

group/family.3)An element with an acquired (+) or (-) charge is

termed an _____.

QUIZ CONT.

4)Identify what groups represent:– S block = – P block = – D block = – F block = 5) Why do elements “give up” or “take” electrons?

Think in terms of outer shell, what is this outer shell called?

What are Periodic Trends?

• Many properties of the elements change in a predictable way, based on their location in the periodic table

• We will look at the following properties:– Atomic radius– Ionic radius– Ionization energy – the energy req’d to remove an

electron from a gaseous atom– Electronegativity – ability of an atom to attract

electrons in a chemical bond

Atomic Radius

• Trends within periods– Decrease in atomic radius as you move from left

to right across a period

• Trends within groups– General increase in atomic radius as you move

down a group

Ionic Radius

An ION is an atom or bonded group of atoms that has a positive or negative charge

• When atoms lose electrons and become positive ions, they always become smaller

• When atoms gain electrons and become negative ions, they become larger

Ionic Radius (cont’d)

• Trends within periods (see Fig 6.14)– Generally, as you move from left to right across a

period, the size of the positive ions decrease– Then, beginning in group 15 or 16, the size of the

much-larger negative ions also gradually decreases

• Trends within groups– As you move down a group, ionic size gradually

increases

Ionization Energy

• Trends within periods– Values of first ionization energies generally

increase as you move from left to right across a period.

• Trends within groups– First ionization energies generally decrease as you

move down a group

The Octet Rule

• Atoms tend to gain, lose, or share electrons in order to acquire a full set of eight valence electrons

• Exception: Hydrogen does not want 8 valence electrons it will usually give up it’s one electron to make a positive ion

Electronegativity

• Electronegativity values range from 0.7 to 3.98

• Fluorine is the most electronegative atom (3.98)• Francium is the least electronegative atom (0.70)

• Many periodic tables list electronegativity values as well