5.3 Periodic Trends.pptx

1869-Russian Chemist, Dmitri Mendeleev:



Designed a Periodic Table 1869



Elements are listed in order of increasing

1913-British Scientist, Henry Moseley:



Designed the Modern Periodic Table



Elements are listed in order of increasing atomic #

Based on Periodic Law: physical & chemical

PERIODICITY

There are general trends in

the properties of atoms and

their ions.

These trends can be

explained using the periodic

table and the electron

Relative strength of metals

and nonmetals

Strong metals can be found to the left and downward on the Periodic Table.

Why?

a)Metals to the left have fewer e’s to lose.

b)Metals toward the bottom of the table are losing

valence e’s which are further away from the pull of the nucleus

Strong nonmetals can be found to the right and upward

on the Periodic Table

Why?

a) Nonmetals on the right have fewer e’s to gain.

Overview of 5.3

I

b) Periodic Trends =

Trends :

• Atomic size

• Electronegativity

• Ionization Energy (1st_,2nd_{, 3}rd₎

• e Affinity

• II. a) Reactivity (strength)

• b) Ion size of metals vs. ion size of nonmetals

Why do inert gases not react?

Metals tend to react by_____________

Nonmetals tend to react by__________

Trends #1- Atomic Radii

D

I

Half the distance between the nuclei in

a molecule consisting of identical

atoms

Atomic size______________

down

a group

.

Why?

•

For each step down, an additional energy level is added.

•

Shielding effect

: the greater # of inner electrons shield the

valence electrons from the nuclear charge.

Atomic size______________

across

a period

.

Why?

Atomic Radii

D

Electronegativity…

the ability of an atom to attract electrons

•

Think of the driving tendencies for metals, nonmetals and

inert gases

•

Predict whether a metal would have a high or low

electronegativity value:_________

•

Predict whether a nonmetal would have a high or low

value:_____

•

Predict whether an inert gas would have a high or low

Ionization energy

the amount of energy needed to remove

an electron from an atom

1st _{I.E. amt. of energy to take 1 e away from an atom.}

2nd _{I.E. amt. of energy to take a second e away from the same atom.}

3rd _{I.E. amt. of energy to take a third e away from the same atom.}

Predict: high or low ioniz. Energy for each: 1.Metal____

Ionic Size: Cation(+) vs. Anion(-)

Cations lose

electrons and get

smaller

Anions gain

PERIODICITY

A

to

m

ic

R

ad

ii

I

nc

re

as

es

Ionization Energy Increases

Atomic Radii Decreases

Electronegativity Increases

Shielding is Constant

Ionic Size (cation)

Decreases