The Periodic TableThe Periodic Table

Early ThoughtsEarly Thoughts

Dobereiner Dobereiner – arranged – arranged elements with similar chemical elements with similar chemical properties into triads. properties into triads.

Newlands- Newlands- arranged elements arranged elements by increasing atomic mass. by increasing atomic mass. Came up with groups of 8 Came up with groups of 8 called them octaves.called them octaves.

Early ThoughtsEarly Thoughts

Mendeleev – Mendeleev – Arranged Arranged elements by atomic masselements by atomic mass

Moseley - Moseley - discovered each discovered each element had a unique element had a unique positive charge in the nucleus positive charge in the nucleus – Atomic number. – Atomic number.

Periodic LawPeriodic Law

Periodic LawPeriodic Law – When – When elements are arranged in elements are arranged in order of increasing atomic order of increasing atomic numbers, their physical and numbers, their physical and chemical properties show a chemical properties show a periodic pattern.periodic pattern.

TermsTerms

Groups or families – Groups or families – the the vertical columns on the periodic vertical columns on the periodic tabletable

Periods –Periods – The horizontal rows of The horizontal rows of the periodic tablethe periodic table

Valence Electrons – electrons in Valence Electrons – electrons in the highest principal energy the highest principal energy level. level.

General TrendsGeneral Trends

Periodic TrendsPeriodic Trends-Allow us to see the -Allow us to see the relationships between the elements relationships between the elements and their position on the periodic and their position on the periodic table table

Down a family – more energy levels, Down a family – more energy levels, more electron shielding.more electron shielding.

Across a period – same energy level, Across a period – same energy level, more protons. Makes the positive more protons. Makes the positive nuclear charge greaternuclear charge greater

Atomic RadiusAtomic Radius

Atomic Radii-Atomic Radii- the size from the the size from the center of the atom to the outer edge.center of the atom to the outer edge.

Period (across the table)-Period (across the table)-As you As you go across the table, the atomic go across the table, the atomic radius DECREASES radius DECREASES

Group-Group- As you go down the table, As you go down the table, the atomic radius INCREASES. the atomic radius INCREASES.

The largest atomic Radius isThe largest atomic Radius is Fr Fr

Ion SizeIon Size

Ion- an atom that has gained or lost one Ion- an atom that has gained or lost one or more electronsor more electrons

““+” ions are smaller than their +” ions are smaller than their corresponding atomscorresponding atoms

““-“ ions are larger than their -“ ions are larger than their corresponding atomscorresponding atoms

Elements in a group form ions of Elements in a group form ions of the same chargethe same charge

Metals form “+” ions, Metals form “+” ions, Nonmetals form “-“ ionsNonmetals form “-“ ions

Ionization energyIonization energy

Ionization EnergyIonization Energy-Tells us how -Tells us how much energy is required to remove much energy is required to remove one electron from an atom. one electron from an atom. (measured in joules/mole)(measured in joules/mole)

A + energy → A+ + e-A + energy → A+ + e-Period-Period-Increase across the period. Increase across the period. Group-Group- decreases as you go down decreases as you go down

the group.the group.

Removing multiple Removing multiple electronselectrons..

ExampleExample, Boron [He] 2s22p1 , Boron [He] 2s22p1 IE1 801, IE2 2427, IE3 3660, IE4 25026, IE1 801, IE2 2427, IE3 3660, IE4 25026,

IE5 32827IE5 32827Where is the big jump in energy and why?Where is the big jump in energy and why? You lose all the valence electrons and You lose all the valence electrons and

are removing core electrons after IE3are removing core electrons after IE3What has the lowest ionization energy What has the lowest ionization energy CsCs

Electron AffinityElectron Affinity-The energy -The energy change that occurs when an electron change that occurs when an electron is acquired by a neutral atom Most is acquired by a neutral atom Most atoms give off energy when an atoms give off energy when an electron is gainedelectron is gained

Electron Affinity trendsElectron Affinity trends

Period TrendsPeriod Trends- as you move across - as you move across the period, the electron affinity the period, the electron affinity increases until you reach the increases until you reach the halogens. halogens.

Group TrendsGroup Trends-As you move down a -As you move down a group, the electron affinity decreases. group, the electron affinity decreases.

Metals have a low E.A. Metals have a low E.A. Nonmetals have a high E.A.Nonmetals have a high E.A.

Exothermic vs. endothermicExothermic vs. endothermic

F + e- → F- -328KJ/MoleF + e- → F- -328KJ/Mole ExothermicExothermic Some atoms gain an electron by putting Some atoms gain an electron by putting

energy into the system. energy into the system. Mg + e- → Mg- +19KJ/MoleMg + e- → Mg- +19KJ/Mole EndothermicEndothermic The second type of reaction is very unstable The second type of reaction is very unstable

and return to their original state and return to their original state spontaneously. These are usually the noble spontaneously. These are usually the noble gases. gases.

ElectronegativityElectronegativity

Electronegativity- Electronegativity- the ability of an the ability of an atom in a molecule to attract electrons atom in a molecule to attract electrons to itselfto itself

Period trend- Period trend- increases across the increases across the period. The metals tend to give period. The metals tend to give electrons away rather than attract them. electrons away rather than attract them.

Group TrendGroup Trend- decreases or stays about - decreases or stays about the samethe same

Noble gases aren't electronegative Noble gases aren't electronegative FF is the most electronegative element. is the most electronegative element.