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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. - PowerPoint PPT Presentation
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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.
A periodic table usually has the following information:
Information on the Periodic Table
NOTE: A periodic table may have more information or less information, depending on the publisher and intended use.
Atomic Number - the number of protons in that particular atom
Atomic Mass - the average atomic mass for that atom
Name of Atom
Element Symbol - the one or two letters designating the atom
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.
peri
ods
groups
1
2
3
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?
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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.
Alka
li M
etal
s
Alka
line
Eart
h M
etal
s
Hal
ogen
s
Nob
le G
ases
Transition Metals
Chal
coge
ns
Groups of Elements
Enjoy Tom Lehrer's Famous Element Song!
Alka
li M
etal
s
Group 1 Alkali Metals (very reactive metals)
Alka
line
Eart
h M
etal
s
Group 2 Alkaline Earth Metals (reactive metals)
Transition Metals
Groups 3 - 12 Transition Metals (low reactivity, typical metals)
Chal
coge
ns
Group 16 Chalcogens (elements of fire)
Hal
ogen
s
Group 17 Halogens (highly reactive, nonmetals)
Group 18 Noble Gases (nearly inert)
Nob
le G
ases
Alka
li M
etal
s
Alka
line
Eart
h M
etal
s
Hal
ogen
s Nob
le G
ases
Transition Metals
Chal
coge
ns
Metals, Nonmetals, and Metalloids
As
BSi
TeGe
Sb?
metals nonmetalsmetalloids
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).
Diatomic ElementsSeven elements in the periodic table are always diatomic.In elemental form, they are always seen as two atoms bonded together.
H
ONClBr
I
F
H2, O2, N2, Cl2, Br2, I2, F2
Alka
li M
etal
s
Alka
line
Eart
h M
etal
s
Hal
ogen
s
Nob
le G
ases
Transition Metals
Chal
coge
ns
Since the families are based on reactivates, and next, how something reacts is based off of how its electrons are arranged. . .
. . . we now know that elements in the same family have very similar electron configurations
Electron Configuration
Group namesNoble Gases - Group 18, s2p6 endingHave a full outermost shell
Halogens - Group 17, s2p5 endingHighly reactive, need one electron to have a full outer shell.
Alkali Metals - Group 1, s1 endingVery reactive
Alkaline Earth Metals - Group 2, s2 ending Reactive
Transition Metals (d-block) - Groups 3 - 12somewhat reactive, typical metals, ns2, (n-1)d ending
Inner transition metals ( f -block) - the bottom two rowssomewhat 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.
1A 2A 8A 1 2 183A 4A 5A 6A 7A
13 14 15 16 17 8B3B 4B 5B 6B 7B 1B 2B 3 4 5 6 7 8 9 10 11 12
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Group Numbers
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.
1234567
67
StabilityElements 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)
1234567
67
StabilityNext in order of stability are elements with full sublevels.
~Full Energy Level ~Full Sublevel (s, p, d, f) ~Half Full Sublevel ( d5, f7)
1234567
67
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)
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.
1234567
67
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.
Electron Configuration Exceptions
1234567
67
Cr
12
3
4
5
6
7
1s
2s2p
3s
3p4s
3d4p
5s4d
5p6s 4f
5d6p
5f7s6d7p
6f7d
7f
Ener
gy
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.
Copper Expect: [Ar] 4s2 3d9 Actually: [Ar] 4s1 3d10
Copper gains stability with a full d-sublevel by taking electrons from the s orbital.
Electron Configuration Exceptions
1234567
67
Cu
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.
A periodic table usually has the following information:
Information on the Periodic Table
NOTE: A periodic table may have more information or less information, depending on the publisher and intended use.
Atomic Number - the number of protons in that particular atom
Atomic Mass - the average atomic mass for that atom
Name of Atom
Element Symbol - the one or two letters designating the atom
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.
peri
ods
groups
1
2
3
4
5
6
7***
***6
7
