Chapter14: Periodic Trends Chapter14: Periodic Trends Modern Chemistry; Holt, Rinehart, & WinstonModern Chemistry; Holt, Rinehart, & Winston

Russian chemist Arranged his periodic table

according to atomic mass so that elements with similar properties were in the same group

Predicted the properties of elements that had not yet been discovered using his periodic table

Russian chemist Arranged his periodic table

according to atomic mass so that elements with similar properties were in the same group

Predicted the properties of elements that had not yet been discovered using his periodic table

Dmitri Mendeleev (1834-1907)Dmitri Mendeleev (1834-1907)

English chemist Proved Mendeleev’s

arrangement of the periodic table to be correct – only, the periodic table was arranged according to atomic number, not atomic mass

English chemist Proved Mendeleev’s

arrangement of the periodic table to be correct – only, the periodic table was arranged according to atomic number, not atomic mass

Henry Moseley (1887-1915)Henry Moseley (1887-1915)

The Periodic LawThe Periodic Law

States that when elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern

States that when elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic pattern

Atomic RadiiAtomic Radii

Atomic radius – the distance between the center of the nucleus and the outer most energy level

Atomic radius – the distance between the center of the nucleus and the outer most energy level

Distance between nuclei

Atomic Radius

Atomic RadiusAtomic Radius

Decreases across a rowDecreases across a row

Group TrendsGroup Trends

Increase down a group Increase down a group

Which element has a larger atomic radius?Which element has a larger atomic radius?

Na or K?

Al or Cl?

F or Sn?

Fr or O?

Na or K?

Al or Cl?

F or Sn?

Fr or O?

K

Al

Sn

Fr

Ionization EnergyIonization Energy

The energy required to remove one electron from a neutral atom of an element creating an ion

The energy required to remove one electron from a neutral atom of an element creating an ion

Ionization EnergyIonization Energy

Increase across a period Increase across a period

Group TrendsGroup Trends

Decrease down the groupDecrease down the group

Which element has a greater ionization

energy?

Which element has a greater ionization

energy?Ca or Br?

C or Ge?

Ba or Cl?

Br or Pb?

Ca or Br?

C or Ge?

Ba or Cl?

Br or Pb?

Br

C

Cl

Br

ElectronegativityElectronegativity

A measure of the ability of an atom in a chemical compound to attract a bonding pair of electrons

A MEASURE OF GREEDINESS!

A measure of the ability of an atom in a chemical compound to attract a bonding pair of electrons

A MEASURE OF GREEDINESS!

ElectronegativityElectronegativity

Increase across a period

Decrease down a group

EXCEPTIONS: NOBLE GAS (GROUP 18). They do not have an electronegativity value because they do not form chemical compounds.

Increase across a period

Decrease down a group

EXCEPTIONS: NOBLE GAS (GROUP 18). They do not have an electronegativity value because they do not form chemical compounds.

Which element has a greater electronegativity?

Which element has a greater electronegativity?

Mg and Ba?

Zn or Br?

Xe or I?

Ge or Ne?

Mg and Ba?

Zn or Br?

Xe or I?

Ge or Ne?

Mg

Br

I

Ge