The Periodic Table

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The Periodic Table. Now that we know where (or approximately  where) to find the parts of atoms, we can  start to understand how these factors all  come together to affect how we view the  elements.

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The Periodic Table

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The Periodic Table

Now that we know where (or approximately  where) to find the parts of atoms, we can  start to understand how these factors all  come together to affect how we view the  elements.

We can look at them as individual yet  interacting chemicals, and we are able to  group them based, not only on the  properties they present when in isolation,  but also the properties they reveal when  exposed to other elements or compounds.

History of the Periodic Table

Dmitri Mendeleev, building on the ideas from chemists before him, developed the  modern periodic table.

He argued that element properties are  periodic functions of their atomic weights.  We now know that element properties are  periodic functions of their atomic number.  By elemental properties, we are describing  both physical and chemical properties.

Atoms are listed on the periodic table in rows, based on  number of protons.

Information on the Periodic Table

A periodic table usually has the following information:

Name of Atom

Element Symbol - the one or two letters  designating the atom

Atomic Number - the number of protons in that particular atom

Atomic Mass - the average atomic mass for that atom

less information, depending on the publisher and intended use.

Periodic Table

The periodic table is made of rows and columns:

Rows in the periodic table are called Periods.

Columns in the periodic table are called Groups.

Groups are sometimes referred to as Families, but "groups" is more traditional.

groups

1

2

3

periods

4

5

*

6

7

**

*

6

**

7

Periodic Table

The periodic table is "periodic" because of certain trends that are  seen in the elements.

Properties of elements are functions of their atomic number.

Elements from the same group have similar physical and  chemical properties.

Atoms are listed on the periodic table in rows, based on number  of protons, which is equal to the number of electrons in a neutral  atom.

[]

1

What is the atomic number for the element in  period 3, group 16?

2

What is the atomic number for the element  in period 5, group 3?

Special Groups

Some groups have distinctive properties  and are given special names.

Alkaline Earth Metals

Noble Gases

Chalcogens

Halogens

Transition Metals

Alkali Metals

Groups of Elements

Enjoy Tom Lehrer's

Famous Element Song!

Transition Metals

Alkaline Earth Metals

Noble Gases

Chalcogens

Halogens

Transition Metals

Alkali Metals

Metals, Nonmetals, and Metalloids

The periodic table can be also divided into metals (blue)  and nonmetals (yellow) . A few elements retain some of  the properties of metals and nonmetals, they are called  metalloids (pink).

B

metals

nonmetals

Si

Ge

As

metalloids

Sb

Te

?

Diatomic Elements

Seven elements in the periodic table are always diatomic.

In elemental form, they are always seen as two atoms  bonded together.

H2, O2, N2, Cl2, Br2, I2, F2

H

O

N

F

Cl

Br

I

Electron Configuration

Since the families are  based on reactivates,  and next, how something  reacts is based off of  how its electrons are  arranged. . .

Alkaline Earth Metals

Noble Gases

Chalcogens

Halogens

Transition Metals

Alkali Metals

. . . we now know that elements in the same family

have very similar electron configurations

Group names

Noble Gases - Group 18, s2p6 ending

Have a full outermost shell

Halogens - Group 17, s2p5 ending

Highly reactive, need one electron to have a full outer shell.

Alkali Metals - Group 1, s1 ending

Very reactive

Alkaline Earth Metals - Group 2, s2 ending

Reactive

Transition Metals (d-block) - Groups 3 - 12

somewhat reactive, typical metals, ns2, (n-1)d ending

Inner transition metals ( f -block) - the bottom two rows

somewhat reactive and radioactive, ns2, (n-2)f ending



3

The elements in the periodic table that  have completely filled shells or subshells  are referred to as:

A

noble gases.

B

halogens.

C

alkali metals.

D

transition elements.

E

I don't know how to answer this.



4

The elements in the periodic table which lack  one electron from a filled shell are referred to  as:

A

noble gases.

B

halogens.

C

alkali metals.

D

transition elements.

E

I don't know how to answer this.



5

The elements in the periodic table which  have a single outer s electron are referred  to as:

A

noble gases.

B

halogens.

C

alkali metals.

D

transition elements.

E

I don't know how to answer this.

Looking back at the Periodic Table of  the Elements

Atoms with the same number of electrons in their outer shells or  same outer electron configuration, have similar chemical behavior.  They appear in the same column of the periodic table.

The periodic table of elements can be grouped into blocks based  on electron configuration of the atoms. s, p, d, and f blocks will  have the last electron in the atom filling into these sub shells  respectively.

The elements with configuration - full or half full in their outer sub  shell are the most distinctive.

Stability

When the elements were studied it was notices that some of them do  not react in certain situations in which others do. These elements were  labeled "stable" because they did not change easily. When these stable  elements were grouped together, it was noticed that periodically, there  were patterns in the occurrence of stable elements.

Today we recognize that this difference in stability is due to electron  configurations.

Group Numbers

1A 2A 8A

1 2 18

3A 4A 5A 6A 7A

13 14 15 16 17

}

8B

3B 4B 5B 6B 7B 1B 2B

3 4 5 6 7 8 9 10 11 12

There are two methods for labeling the groups, the older  method shown in black on the top and the newer method  shown in blue on the bottom.

Stability

Elements of varying stability fall into one of 3 categories. The most  stable atoms have completely full energy levels.

~Full Energy Level

~Full Sublevel (s, p, d, f)

~Half Full Sublevel ( d5, f7)

1

2

3

4

5

6

7

6

7

Stability

Next in order of stability are elements with full sublevels.

~Full Energy Level

~Full Sublevel (s, p, d, f)

~Half Full Sublevel ( d5, f7)

1

2

3

4

5

6

7

6

7

Stability

Finally, the elements with half full sublevels are also stable, but not as  stable as elements with fully energy levels or sublevels.

~Full Energy Level

~Full Sublevel (s, p, d, f)

~Half Full Sublevel ( d5, f7)

1

2

3

4

5

6

7

6

7

Electron Configuration Exceptions

You should know the basic exceptions in the d- and f-sublevels.  These fall in the circled areas on the table below.

1

2

3

4

5

6

7

6

7

Electron Configuration Exceptions

Chromium

Expect: [Ar] 4s2 3d4 Actually: [Ar] 4s1 3d5

Sometimes, in order to atleast get a half full d sublevel, some  elements will cheat a bit and steal electrons from an s sublevel. To  see why this can happen we need to examine how "close" d and s  sublevels are.

1

2

3

4

5

6

7

Cr

6

7

Energies of Orbitals

Because of how close the f  and d orbitals are to the s  orbitals en electron can easily  be taken from the s orbital  (leaving it half full) and given  to the f or d orbital, causing  them to also be half full.

Its kind of like borrowing a cup  of sugar from a neighbor.  You'd only borrow it from  someone you were close to,  and only if you needed it. It's  the same thing for electrons.

7f

7d

6f

7

7p

6d

5f

6

7s

6p

5d

4f

5

6s

5p

Energy

4d

4

5s

4p

3d

3

4s

3p

2

3s

2p

1

2s

1s

Electron Configuration Exceptions

Copper

Expect: [Ar] 4s2 3d9 Actually: [Ar] 4s1 3d10

Copper gains stability with a full d-sublevel by taking  electrons from the s orbital.

Cu

1

2

3

4

5

6

7

6

7

The Periodic Table

Now that we know where (or approximately  where) to find the parts of atoms, we can  start to understand how these factors all  come together to affect how we view the  elements.

We can look at them as individual yet  interacting chemicals, and we are able to  group them based, not only on the  properties they present when in isolation,  but also the properties they reveal when  exposed to other elements or compounds.

History of the Periodic Table

Dmitri Mendeleev, building on the ideas from chemists before him, developed the  modern periodic table.

He argued that element properties are  periodic functions of their atomic weights.  We now know that element properties are  periodic functions of their atomic number.  By elemental properties, we are describing  both physical and chemical properties.

Atoms are listed on the periodic table in rows, based on  number of protons.

Information on the Periodic Table

A periodic table usually has the following information:

Name of Atom

Element Symbol - the one or two letters  designating the atom

Atomic Number - the number of protons in that particular atom

Atomic Mass - the average atomic mass for that atom

less information, depending on the publisher and intended use.

Periodic Table

The periodic table is made of rows and columns:

Rows in the periodic table are called Periods.

Columns in the periodic table are called Groups.

Groups are sometimes referred to as Families, but "groups" is more traditional.

groups

1

2

3

periods

4

5

*

6

7

**

*

6

**

7