Chapter 5The Periodic Table

Periodic Table Info

Periodic Table Development

Dimitri Mendeleev (1834 – 1907)• Arranged the elements by increasing ATOMIC

MASS

• Produced the first PERIODIC TABLE – 1871

• The table placed elements with similar properties in the same column

• Kept “holes” for undiscovered elements, and predicted the properties in advance

Mendeleev’s Periodic Table

Predicting Properties

New Periodic Table

H. G. Moseley (1887-1915)

• Rearranged the elements by ATOMIC NUMBER

• This is the MODERN PERIODIC TABLE

What’s on the Periodic Table?

• GROUP: vertical column (family)similar chemical properites

• PEROID: horizontal rowsame filled energy levels

Reading the Periodic Table

Period

Group

1

2

3

4

5

6

7

Periodic Table Groups

Properties of Metals

1. shiny (luster)

2. conductors of heat and electricity

3. Reactive with acids

4. ductile

– can be stretched into a wire

5. malleable

– can be hammered or rolled into sheets

Properties of Nonmetals

1. Dull and brittle

2. poor conductors of heat and electricity

3. Does not react with acids

4. usually gases at room temp.

PERIODIC LAW

• When elements are arranged in order of increasing atomic number, their physical and chemical properties show a periodic (repeating) pattern.

Which means:

• there are patterns across the periodic table called periodic trends

Atomic Radius

half the distance from center-center of 2 like atoms

Atomic Radii DOWN a Group

↓ As you go down a group another energy level is added, the atom size gets larger

Na

Atomic Radius: down group

P

PP

X

X

X

P

X

P

X

P

X

P

PP

P

P

X

X

X

X

X

XP

K

Atomic Radius: down group

P

PP

X

X

X

P

X

P

X

P

X

P

PP

P

P

X

X

X

X

X

P

X

X

X

X

X

X

X

X

X

Atomic Radii DOWN a Group

↓ DOWN THE GROUP ATOMIC RADIUS

INCREASES

more energy levels,

the larger the size of the atom

Atomic Radii ACROSS a Period

→ Each atom gains one proton and one electron in the same energy level

→Each added electron is the same distance from the nucleus

→The positive charge increases and exerts a greater force on the electrons thereby pulling it closer to the nucleus

REMEMBER!PROTONSare bigger

and stronger!

electrons

are smaller

and weaker!P+ + - -

e

Atomic Radius: across period

P

PP

X

X

X

P

X

P

X

P

X

P

PP

P

P

X

X

X

X

X

Atomic Radii ACROSS a Period

→ACROSS THE PERIOD ATOMIC RADIUS

DECREASES

stronger attraction of protons,

easier to hold on to the electrons

amount of energy needed to remove an electron from an atom

Ion: an atom that has gained or lost electrons

if you lose an electron…

if you gain an electron…

Ionization Energy

BECOMES POSITIVE!

BECOMES NEGATIVE!

Ionization Energy DOWN a Group

↓ As you go down a group atoms become larger, electrons are farther from the nucleus and more easily removed

Ionization Energy DOWN a Group

↓ DOWN THE GROUP IONIZATION ENERGY

DECREASES

greater distance from the nucleus, the easier to lose an electron

(less energy needed)

Ionization Energy ACROSS a Period

→As atomic radius decreases there is a greater attraction between protons and electrons.

→The stronger the attraction, the more energy needed to remove an electron.

→The more electrons present, the more energy required to remove them all to become STABLE

Ionization Energy ACROSS a Period

→ACROSS THE PERIOD IONIZATION ENERGY

INCREASES

more electrons on an energy level,

more energy required to remove them all

It is a “tug of war” between the two atoms of a bond

Electronegativity

H F :

::

Which is the more electronegative element?

.

..

tendency for an atom to attract electrons

Electronegativity ACROSS the Period

→As you go across a period atomic radius decreases because there is a greater attraction between protons and electrons

→Metals do not attract electrons. →Non-metals do attract electrons.

Electronegativity ACROSS the Period

→ACROSS THE PERIOD ELECTRONEGATIVITY

INCREASES

stronger the attraction,

the easier to add more electrons

Electronegativity DOWN the Group

↓ The larger the atom, the less likely it is to accept more electrons.

Electronegativity DOWN the Group

↓ DOWN THE GROUP ELECTRONEGATIVITY

DECREASES

farther the distance from the nucleus,

more difficult to attract electrons

PUT IT ALL TOGETHER!

Reactivity of Alkali Metals

Where are the most reactive metals?

Where are the most reactive nonmetals?

Activity Series of the Elements

1.Why is sodium not used for silverware?

It is highly reactive and reacts with water.

2. Why has so much gold 2. Why has so much gold jewelry survived from ancient jewelry survived from ancient

civilizations?civilizations?It does not react with oxygen or water and therefore does not readily break down.

3. Why is food canned in containers made from steel

coated with a thin layer of tin?Steel makes a strong container and the tin lining does not react with the contents.

 

4. Why are cars painted?

To prevent the iron from rusting by being exposed to oxygen in air.