Periodic TablePeriodic Table

Chapter 6Chapter 6

Periodic TablePeriodic Table

A chart that organizes all known A chart that organizes all known elements into a grid of horizontal elements into a grid of horizontal rows, periods, and vertical columns, rows, periods, and vertical columns, groups, arranged by increasing groups, arranged by increasing atomic number.atomic number.

Development of Modern Periodic Development of Modern Periodic TableTable

Mendeleev, First atomic Mendeleev, First atomic table, about 63 elementstable, about 63 elements

Organized by atomic massOrganized by atomic mass Connected atomic mass to Connected atomic mass to

properties of elementsproperties of elements

MedeleevMedeleev

Periodic LawPeriodic Law

Henry Moseley, atomic number.Henry Moseley, atomic number. Periodic Law: periodic repetition of Periodic Law: periodic repetition of

chemical and physical properties of chemical and physical properties of the elements.the elements.

Modern Periodic TableModern Periodic Table

Increasing atomic numberIncreasing atomic number Horizontal rows called periodsHorizontal rows called periods Vertical columns called groups or Vertical columns called groups or

familiesfamilies Main group, representative, elementsMain group, representative, elements Transition ElementsTransition Elements

Modern Periodic TableModern Periodic Table

Metals: left side, good conductors, Metals: left side, good conductors, solids usuallysolids usually

Metaloids: Stair step, similar Metaloids: Stair step, similar properties of metals and nonmetalsproperties of metals and nonmetals

Nonmetals: right side, gases or dull Nonmetals: right side, gases or dull solids, poor conductorssolids, poor conductors

Alkali MetalsAlkali Metals

Group 1A – excluding hydrogenGroup 1A – excluding hydrogen Shiny, malleable, ductile, good Shiny, malleable, ductile, good

conductorsconductors 1 valence electron, readily forms +1 1 valence electron, readily forms +1

cationcation Reacts violently with waterReacts violently with water Reactivity increases as you go down Reactivity increases as you go down

column.column.

Alkali Earth MetalsAlkali Earth Metals

Group 2A or 2Group 2A or 2 Ca, Ba, and Sr react with waterCa, Ba, and Sr react with water 2 valence electrons, therefore form 2 valence electrons, therefore form

+2 cations.+2 cations.

HalogensHalogens

Highly reactive groupHighly reactive group 7A or 177A or 17 Most are gassesMost are gasses 7 valence electrons, from -1 anion 7 valence electrons, from -1 anion

easilyeasily

Noble GassesNoble Gasses

Group 8A or 18Group 8A or 18 Formally called inert gasses but Formally called inert gasses but

actually can react, Xeactually can react, Xe Full outer energy levelFull outer energy level

Periodic TrendsPeriodic Trends

Atomic RadiiAtomic Radii Increase down Increase down

familyfamily Why?Why? Decreases down Decreases down

periodperiod Why?Why? Higher effective Higher effective

nuclear charge.nuclear charge.

Ionization Energy (IE)Ionization Energy (IE)

Energy required to remove an electron Energy required to remove an electron from an atom.from an atom.

How strongly an atom’s nucleus holds onto How strongly an atom’s nucleus holds onto its valence electron.its valence electron.

↑ ↑ IE, less likely to form positive ionsIE, less likely to form positive ions As you move across period IE increases.As you move across period IE increases. Why?Why? Increased Charge has stronger hold on Increased Charge has stronger hold on

electronselectrons

Ionization Energy (IE)Ionization Energy (IE)

As you move down group the IE As you move down group the IE decreases.decreases.

Why?Why? Electron shielding, further awayElectron shielding, further away

Octet RuleOctet Rule

States that all atoms tend to gain, States that all atoms tend to gain, lose, or share electrons in order to lose, or share electrons in order to acquire a full set of eight valence acquire a full set of eight valence electrons.electrons.

Understanding octet rule helps Understanding octet rule helps determine ions.determine ions.

Metals form cations, nonmetals form Metals form cations, nonmetals form anions.anions.

ElectronegativityElectronegativity

Relative ability of the atoms to attract Relative ability of the atoms to attract electrons in a chemical bond.electrons in a chemical bond.

Decreases down groupsDecreases down groups Increases across periodIncreases across period Francium least electronegativeFrancium least electronegative Fluorine most electronegativeFluorine most electronegative