Organization of the Periodic Table. Columns of the periodic table Atoms of elements in the same group have the same # of valence electrons and therefore

Periodic TrendsOrganization of the Periodic Table

GROUPS

Columns of the periodic table Atoms of elements in the same

group have the same # of valence electrons and therefore behave similarly

PERIODS•Rows of the periodic table•All elements in a period have their valence electrons in the same energy level.

Which of the following are in the same group?

H, H

e, C, L

i

K, Ca, A

s, Br

He, N

e, Kr,

Ar

B, Al, G

e, Sn

0% 0% 0% 0%

1. H, He, C, Li2. K, Ca, As, Br3. He, Ne, Kr, Ar4. B, Al, Ge, Sn

Which of the following are in the same period?

H, H

e, C, L

i

K, Ca, A

s, Br

He, N

e, Kr,

Ar

B, Al, G

e, Sn

0% 0% 0% 0%

1. H, He, C, Li2. K, Ca, As, Br3. He, Ne, Kr, Ar4. B, Al, Ge, Sn

Representative and Transition Elements

Valence Electrons Valence Electrons are electrons in the

outermost energy level.

- s or p electrons only (even when d and f electrons are present they are not in the outermost energy level)

Electron Dot Diagrams Electron Dot Diagrams show the valence

electrons of an element.

Draw the electron dot diagrams for the following:

Mg N F

How many valence electrons are in the halogens?

1 2 7 8

0% 0% 0% 0%

1. 12. 23. 74. 8

How many valence electrons are in Group 17?

1 2 7 8

0% 0% 0% 0%

1. 12. 23. 74. 8

How many valence electrons are in zinc and chromium?

1 2 7 8

Unable to

tell

0% 0% 0% 0% 0%

1. 12. 23. 74. 85. Unable to tell

Size of the Atom Think of a ball of an onion. What happens

with each layer?

As you go down the periodic table, the energy levels increase and the size of the radius of the atom increases. (each energy level is like another layer of the onion)

Which element has a larger atomic radius: Na or K?

Na K

Unable to

be determ

ined

0% 0% 0%

1. Na2. K3. Unable to be

determined

Which element has a larger atomic radius: Br or Cl?

Br Cl

Unable to

be determ

ined

0% 0% 0%

1. Br2. Cl3. Unable to be

determined

Atomic Radius cont.

• As you move from left to right in the periodic table, what happens to the number of protons in the nucleus?

• What effect do these protons have on the electrons?

• What effect do the electrons have on each other?

Electron Shielding

• Electron Shielding (or Screening) – These inner electrons shield the valence electrons from receiving the entire attractive nuclear charge because they repel the valence electrons.

Nuclear Charge and Atomic Radius Within a period, as you go from left to right,

the positive nuclear charge increases, and attracts the electrons more strongly.

As the electrons are more attracted to the nucleus, the atomic radius decreases.

Summary: as you go from left to right, the atomic radius generally decreases.

Which element has a larger atomic radius: Li or Be?

Li Be

Unable to

be determ

ined

0% 0% 0%

1. Li2. Be3. Unable to be

determined

Which element has a larger atomic radius: Si or Ar?

Si A

r

Unable to

be d...

0% 0% 0%

1. Si2. Ar3. Unable to be

determined

Which element has a larger atomic radius: Be or Mg?

Be M

g

Unable to

be d...

0% 0% 0%

1. Be2. Mg3. Unable to be

determined

Which element has a larger atomic radius: Si or C?

C Si

Unable to

be d...

0% 0% 0%

1. C2. Si3. Unable to be

determined

Octet Rule The octet rule states that all atoms

attempt to become stable by having a full valence electron shell (generally 8 electrons, hence octet rule).

Atoms will gain, lose, or share electrons in order to attain this stability.

Which group already has a full octet?

Alkali m

etals

Transiti

on met..

.

Halogens

Noble G

ases

0% 0% 0% 0%

1. Alkali metals2. Transition metals3. Halogens4. Noble Gases

Which group is one electron away from a full octet?

14% 14% 14% 14% 14% 14% 14%1. Alkali metals2. Transition metals3. Halogens4. Alkaline earth

metals5. Both alkali metals

and halogens6. Noble gases7. Both alkali metals

and alkaline earth metals

Ionization Energy Electrons are held in atoms by their

attraction to the positively charged nucleus.

To remove an electron requires energy.

Ionization energy is the energy required to remove the least tightly bound (or outermost) electron from an atom.

Ionization Energy cont. Compare Li and K.

How many valence electrons?

What is the relative size of the atoms?

Which has a higher ionization energy?

Ionization Energy As you go down a group, the ionization

energy decreases because it takes less energy to remove an electron.

The least tightly bound electrons are further from the positive nucleus, and can therefore be removed more easily.

Which group has a higher ionization energy?

Halogens

Alkali M

etals

Alkalin

e Earth M

etals

All t

he same

0% 0% 0% 0%

1. Halogens2. Alkali Metals3. Alkaline Earth

Metals4. All the same

Which element has a higher ionization energy?

Li Be F Ne

0% 0% 0% 0%

1. Li2. Be3. F4. Ne

Which element has the lowest ionization energy?

Na

Mg S A

r

0% 0% 0% 0%

1. Na2. Mg3. S4. Ar

Summary Ionization energy generally decreases as

you go down a group and from right to left in a period.

Ionization energy

A Quick Review …

How many valence electrons does oxygen have?

1 3 4 6 8

0% 0% 0% 0% 0%

1. 12. 33. 44. 65. 8

Which has the biggest atomic radius?

K Na Li Be Cs

Ca F

0% 0% 0% 0% 0% 0% 0%

1. K2. Na3. Li4. Be5. Cs6. Ca7. F

What is the effective nuclear charge on lithium?

1 2 3

None of t

he ab...

0% 0% 0% 0%

1. 12. 23. 34. None of the above

Which has the greatest ionization energy?

K Na Li Be Cs

Ca F

0% 0% 0% 0% 0% 0% 0%

1. K2. Na3. Li4. Be5. Cs6. Ca7. F

How many valence electrons are in group 14?

1 4 7 14

0% 0% 0% 0%

1. 12. 43. 74. 14

Second, Third, etc. Ionization Energy Second ionization is the energy required to

remove a second electron. Ex. Sodium has a lower (first) ionization

energy than Magnesium but Mg has a lower second ionization energy than Na.

Why?

Which has a lower third ionization energy?

K Ca G

a C

0% 0% 0% 0%

1. K2. Ca3. Ga4. C

Electronegativity Electronegativity is the tendency of an

element to attract electrons in a bond.

Therefore, elements that want to gain electrons will have higher electronegativity.

attractive

Which group of elements is most likely to gain electrons to become stable?

Alkali M

etals

Transiti

on Met..

.

Halogens

Noble G

ases

0% 0% 0% 0%

1. Alkali Metals2. Transition Metals3. Halogens4. Noble Gases

Which has the greatest electronegativity?

K Na Li Be Cs

Ca F

0% 0% 0% 0% 0% 0% 0%

1. K2. Na3. Li4. Be5. Cs6. Ca7. F

Which group has the lowest electronegativity (not counting noble gases)?

Alkali m

etals

Alkalin

e earth...

Halogens

Transiti

on Met..

.

0% 0% 0% 0%

1. Alkali metals2. Alkaline earth

metals3. Halogens4. Transition Metals

Trend Summaries

The pattern forincreasing electronegativity(except for noble gases).

The pattern for increasing ionization energy.

The pattern for increasingatomic radius.

Ions When an atom loses or gains electrons, it

gains a charge. An ion is a charged atom.

A positive ion is called a cation. (ex. Na+)

A negative ion is called an anion. (ex. S2-)

Size of Ions Cations (positive) – lose valence electrons in

the outermost energy level.◦ They lose an energy level so they get smaller.

Anions (negative) – gain valence electrons but their Zeff does not change.◦ They get bigger because of having more electrons

and the same Zeff

Which is a bigger atom?

Mg

Mg+

Mg2+

0% 0% 0%

1. Mg2. Mg+

3. Mg2+


O O-

O2-

0% 0% 0%

1. O2. O-

3. O2-


Ca Ca+

Ca2+

0% 0% 0%

1. Ca2. Ca+

3. Ca2+


S S- S2-

0% 0% 0%

1. S2. S-

3. S2-

Cations Groups 1-13 become cations by losing

electrons because of their low ionization energy.

Their positive charge corresponds to their group number.

Anions Groups 15-17 become anions by gaining

electrons because of their high electronegativity.

Their negative charge corresponds to how many electrons they must gain to have the same electron configuration as a noble gas.

Which of the following describes the tendency for an element to attract an electron in a bond?

Ioniza

tion energy

Ato

mic ra

dius

Thermal c

apacity

Electronegativity

0% 0% 0% 0%

1. Ionization energy2. Atomic radius3. Thermal capacity4. Electronegativity

Which of the following elements is most likely to carry a +2 charge as a cation?

Aluminum

Oxy

gen

Magnesiu

m

Lith

ium

0% 0% 0% 0%

1. Aluminum2. Oxygen3. Magnesium4. Lithium

If an element has a high electronegativity it also has a large:

Ato

mic ra

dius

Ioniza

tion Energy

Ato

mic M

ass

Ionic

Charge

0% 0% 0% 0%

1. Atomic radius2. Ionization Energy3. Atomic Mass4. Ionic Charge

4 Different kinds of metals◦ Alkali metals: soft, shiny and very reactive

Group 1: not found in nature as elements◦ Alkaline earth-metals: less reactive

Group 2: have two valence electrons◦ Transition Metals: many uses

Groups 3-12

METALS

3 Different kinds of metals◦ Noble Gases: mostly non-reactive, very stable

Group 8: He, Ne, Ar, Kr, Xe, Rn◦ Halogens: very reactive, gain one electron to

form a stable compound Group 7: F, Cl, Br, I

NONMETALS

Seven elements are called diatomic and never exist alone in nature.

Have No Fear Of Ice Cold Beans????? H2

N2

F2

O2

I2 Cl2 Br2

Diatomic Gases

Magnesium is in which group?

Alkali m

etals

Alkalin

e earth...

Transiti

on met..

.

Halogens

Noble gase

s

0% 0% 0% 0% 0%


metals3. Transition metals4. Halogens5. Noble gases

Lithium is in which group?

Alkali m

etals

Alkalin

e earth...

Transiti

on met..

.

Halogens

Noble gase

s

0% 0% 0% 0% 0%



Manganese is in which group?

Alkali m

etals

Alkalin

e earth...

Transiti

on met..

.

Halogens

Noble gase

s

0% 0% 0% 0% 0%



Krypton is in which group?

Alkali m

etals

Alkalin

e earth...

Transiti

on met..

.

Halogens

Noble gase

s

0% 0% 0% 0% 0%



The majority of the diatomic gases are in which group?

Alkali m

etals

Alkalin

e earth...

Transiti

on met..

.

Halogens

Noble gase

s

0% 0% 0% 0% 0%



Metals◦Shiny ◦Solids◦Stretched and

Shaped◦Conductors of

heat and electricity

Nonmetals◦Solids, liquids or

gases◦Solids – dull and

brittle◦Poor conductors of

heat and electricity

****Semiconductors / Metalloids – exhibit properties of both metals and nonmetals

FAMILIES OF ELEMENTS

Metals◦ On the left hand side of

the zigzag line (except for Hydrogen – exception)

- Metalloids or Semi-metals- Touching zigzag line (Except for Al)- Exhibit properties of both metals and nonmetals

Nonmetals◦ On the right hand

side of the zig zag line (plus Hydrogen)

How do you tell if it’s a metal, nonmetal, or metalloid?

The difference in electronegativity between atoms A and B is given by:

Documents

Organization of the Periodic Table. Columns of the periodic table Atoms of elements in the same group have the same # of valence electrons and therefore