Chapter 4Chapter 4

The Periodic TableThe Periodic Table

Organizing the ElementsOrganizing the Elements

Dmitri Mendeleev – Constructed the first Dmitri Mendeleev – Constructed the first Periodic Table in 1869 The elements were Periodic Table in 1869 The elements were arranged according to their chemical arranged according to their chemical propertiesproperties

Vertical columns were in order of Vertical columns were in order of increasing atomic massincreasing atomic mass

The columns were arranged so that The columns were arranged so that elements with the most similar properties elements with the most similar properties were side by sidewere side by side

Mendeleev even left blank spaces for Mendeleev even left blank spaces for elements that he believed existed, but elements that he believed existed, but were not yet discovered, one example were not yet discovered, one example was…was…

Ekasilicon… now element 32 Germanium.Ekasilicon… now element 32 Germanium.

Henry Moseley – in 1913 Moseley, a Henry Moseley – in 1913 Moseley, a British physicist determined an atomic British physicist determined an atomic number* for each known element and number* for each known element and arranged the Periodic Table by order of arranged the Periodic Table by order of atomic number.atomic number.

This is the way the Periodic Table is This is the way the Periodic Table is arranged today.arranged today.

Periodic Law: When elements are Periodic Law: When elements are arranged in order of increasing atomic arranged in order of increasing atomic number there is a periodic repetition of number there is a periodic repetition of Physical and Chemical properties. Physical and Chemical properties.

Metals Nonmetals and MetalloidsMetals Nonmetals and Metalloids Over 80% of the elements are MetalOver 80% of the elements are Metal Metals are...Metals are...

Good Conductors of heat and electricityGood Conductors of heat and electricity Metallic luster or sheen, its ability to reflect light.Metallic luster or sheen, its ability to reflect light. Malleable: Ability to be hammered into sheets or foil.Malleable: Ability to be hammered into sheets or foil. Ductile: Ability to be drawn into wire.Ductile: Ability to be drawn into wire. Solid @ room temp (except Hg)Solid @ room temp (except Hg)

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Nonmetals are located in the upper right Nonmetals are located in the upper right corner of the periodic table, to the right of corner of the periodic table, to the right of the stair shaped line.the stair shaped line.

Nonmetals have a great variation in Nonmetals have a great variation in physical properties…gases, solids, one physical properties…gases, solids, one liquid Br.liquid Br.

Nonmetals are poor conductors, their Nonmetals are poor conductors, their solids are brittle.solids are brittle.

Metalloids are located on the stair shaped Metalloids are located on the stair shaped line, outlined on our chart in green.line, outlined on our chart in green.

Metalloids have properties of both metals Metalloids have properties of both metals and non metals. In general they…and non metals. In general they… Have metallic lusterHave metallic luster Conduct electricity, but not as well as a metal, Conduct electricity, but not as well as a metal,

(semiconductor)(semiconductor) Are brittle, they will shatter if hit with a Are brittle, they will shatter if hit with a

hammer.hammer. They are used extensively in the electronics They are used extensively in the electronics

industry for computer chips and circuits.industry for computer chips and circuits.

Periods – the horizontal rows of the Periods – the horizontal rows of the Periodic Table.Periodic Table.

Groups – the vertical columns of the Groups – the vertical columns of the Periodic Table.Periodic Table.

Classifying the ElementsClassifying the Elements

1.1. Noble gases – elements in which the Noble gases – elements in which the outermost s and p sublevels are filled. Group outermost s and p sublevels are filled. Group 18 on the chart. 18 on the chart.

2.2. Representative elements – elements whose Representative elements – elements whose outermost s and p sublevels are only partially outermost s and p sublevels are only partially filled. Groups 1,2 and 13-18 on the chart (tall)filled. Groups 1,2 and 13-18 on the chart (tall)

1.1. Group 1 = alkali metalsGroup 1 = alkali metals

2.2. Group 2 = alkaline earth metalsGroup 2 = alkaline earth metals

3.3. Group 17 = halogensGroup 17 = halogens

4.4. Group 18 = noble gasesGroup 18 = noble gases

cont.cont.

3. Transition metals – elements whose 3. Transition metals – elements whose outermost s sublevel and the nearby d outermost s sublevel and the nearby d sublevel contain electrons (Groups 3-12)sublevel contain electrons (Groups 3-12)

4. Inner transition metals – elements whose 4. Inner transition metals – elements whose outermost s sublevel and nearby f sublevel outermost s sublevel and nearby f sublevel contain electrons… the two rows below contain electrons… the two rows below the tablethe table

6.3 Periodic Trends6.3 Periodic Trends

Atomic Radius: Is one half the distance Atomic Radius: Is one half the distance between the nuclei of two atoms of the between the nuclei of two atoms of the same element when the atoms are joined.same element when the atoms are joined.

““In general, atomic size increases from top In general, atomic size increases from top to bottom within a group and decreases to bottom within a group and decreases from left to right across a period…”from left to right across a period…”

Largest in the lower left corner.Largest in the lower left corner.

cont. Ionscont. Ions

An Ion is an atom or group of atoms that have a An Ion is an atom or group of atoms that have a positive or negative charge.positive or negative charge.

Positive and negative ions form when electrons Positive and negative ions form when electrons are transferred between atoms.are transferred between atoms.

Cations are positive ions… (generally metals) Cations are positive ions… (generally metals) formed when atoms lose electrons to obtain the formed when atoms lose electrons to obtain the electron configuration of a noble gas.electron configuration of a noble gas.

Anions are negative ions… (generally Anions are negative ions… (generally nonmetals) formed when atoms gain electrons to nonmetals) formed when atoms gain electrons to obtain a noble gas electron configuration.obtain a noble gas electron configuration.

Ionization energyIonization energy

Ionization energy – the energy required to Ionization energy – the energy required to overcome the attraction of the nuclear overcome the attraction of the nuclear charge and remove an electron from a charge and remove an electron from a gaseous atom.gaseous atom. The ionization energy decreases as you move The ionization energy decreases as you move

down a group of the periodic tabledown a group of the periodic table

The ionization energy increases as you move The ionization energy increases as you move across a period of the periodic tableacross a period of the periodic table

Ionic SizeIonic Size

Positive ions are smaller than the atoms Positive ions are smaller than the atoms they are formed fromthey are formed from

Negative ions are larger than the atoms Negative ions are larger than the atoms they are formed fromthey are formed from Ionic size tends to increase as you move Ionic size tends to increase as you move

down a group in the periodic tabledown a group in the periodic table

Ionic size tends to decrease as you move Ionic size tends to decrease as you move across a period in the periodic tableacross a period in the periodic table

ElectronegativityElectronegativity

Electronegativity – the tendency for the Electronegativity – the tendency for the atoms of the elements to attract electrons atoms of the elements to attract electrons when they are chemically combined with when they are chemically combined with another elementanother element Electronegativity tends to decrease as you Electronegativity tends to decrease as you

move down a group in the periodic tablemove down a group in the periodic table

Electronegativity tends to increase as you Electronegativity tends to increase as you move across a period in the periodic tablemove across a period in the periodic table