ghs honors chem - chapter 5 chemical periodicity...

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1 GHS Honors Chem Chapter 5 Chemical Periodicity GHS Honors Chem Classification of the Elements OBJECTIVES: Explain why you can infer the properties of an element based on those of other elements in the periodic table. Use electron configurations to classify elements as noble gases, representative elements, transition metals, or inner transition metals. GHS Honors Chem Periodic Table Revisited Russian scientist Dmitri Mendeleev taught chemistry in terms of properties. Mid 1800’s - molar masses of elements were known. Wrote down the elements in order of increasing mass. Found a pattern of repeating properties. GHS Honors Chem Mendeleev’s Table Grouped elements in columns by similar properties in order of increasing atomic mass. Found some inconsistencies - felt that the properties were more important than the mass, so switched order. Also found some gaps. Must be undiscovered elements. Predicted their properties before they were found. GHS Honors Chem Mendeleev's Periodic Table (1871) GHS Honors Chem The Modern Periodic Table Elements are still grouped by properties. Similar properties are in the same column. In 1913, Moseley changed the order to increasing atomic number. This added a column of elements Mendeleev didn’t know about. The noble gases weren’t found because they didn’t react with anything.

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Page 1: GHS Honors Chem - Chapter 5 Chemical Periodicity …schoolwires.henry.k12.ga.us/cms/lib08/GA01000549... · GHS Honors Chem Chapter 5 Chemical Periodicity ... classify elements as

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GHS Honors Chem

Chapter 5Chemical Periodicity

GHS Honors Chem

Classification of the Elements

OBJECTIVES:� Explain why you can infer the

properties of an element based on those of other elements in the periodic table.

� Use electron configurations to classify elements as noble gases, representative elements, transition metals, or inner transition metals.

GHS Honors Chem

Periodic Table Revisited� Russian scientist Dmitri Mendeleev

taught chemistry in terms of properties.

� Mid 1800’s - molar masses of elements were known.

� Wrote down the elements in order of increasing mass.

� Found a pattern of repeating properties.

GHS Honors Chem

Mendeleev’s Table� Grouped elements in columns by similar

properties in order of increasing atomic mass.

� Found some inconsistencies - felt that the properties were more important than the mass, so switched order.

� Also found some gaps.� Must be undiscovered elements.� Predicted their properties before they

were found.

GHS Honors Chem

Mendeleev's Periodic Table(1871)

GHS Honors Chem

The Modern Periodic Table� Elements are still grouped by properties.� Similar properties are in the same

column.� In 1913, Moseley changed the order to

increasing atomic number.� This added a column of elements

Mendeleev didn’t know about.� The noble gases weren’t found because

they didn’t react with anything.

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GHS Honors Chem

� Horizontal rows are called Periods� There are 7 periods

76

1

2

34

5

GHS Honors Chem

Vertical columns called groupsElements are placed in columns by similar propertiesAlso called families

GHS Honors Chem

1A

2A 3A 4A 5A 6A 7A

8A0

The elements in the A groups are called the REPRESENTATIVEelementsouter s or p filling

GHS Honors Chem

The group B are called the transition elements

These are called the inner transition elements, and they belong here

GHS Honors Chem

� Group 1A are the alkali metals� Group 2A are the alkaline earth metals

GHS Honors Chem

� Group 7A is called the Halogens� Group 8A are the Noble Gases

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GHS Honors Chem

Why is the Periodic Table arranged in Groups and Periods?

� The part of the atom another atom sees is the electron cloud.

� More importantly the outside orbitals. � The orbitals fill up in a regular pattern.� The outside orbital electron

configuration, or VALENCE electron configuration, repeats.

� The properties of atoms repeat.

GHS Honors Chem

1s1

1s22s1

1s22s22p63s1

1s22s22p63s23p64s1

1s22s22p63s23p64s23d104p65s1

1s22s22p63s23p64s23d104p65s24d10 5p66s1

1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s1

H1

Li3

Na11

K19

Rb37

Cs55

Fr87

Group 1A Alkali metals• 1 Valence Electron

• s1 configuration• Become +1 ions to

obtain the OCTET ofelectrons

GHS Honors Chem

4Be: 1s22s2

12Mg: 1s22s22p63s2

20Ca: 1s22s22p63s23p64s2

38Sr: 1s22s22p63s23p64s23d104p65s2

56Ba: 1s22s22p63s23p64s23d104p65s24d10

5p66s2

88Ra: 1s22s22p63s23p64s23d104p65s24d105p6

6s24f145d106p67s2

Group 2A Alkaline Earth Metals• 2 Valence Electrons

• s2 configuration• Become +2 ions to

obtain OCTET ofelectrons

GHS Honors Chem

1s22s22p5 9F

1s22s22p63s23p517Cl

1s22s22p63s23p64s23d104p5 35Br

1s22s22p63s23p64s23d104p65s24d105p5 53I

1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p5 85At

Group 7A Halogens• 7 Valence Electrons• s2p5 configuration• Become -1 ions to achieve

their octet of electrons

GHS Honors Chem

He2

Ne10

Ar18

Kr36

Xe54

Rn86

1s2

1s22s22p6

1s22s22p63s23p6

1s22s22p63s23p64s23d104p6

1s22s22p63s23p64s23d104p65s24d105p6

1s22s22p63s23p64s23d104p65s24d10

5p66s24f145d106p6

Group 8A Noble Gases• 8 Valence Electrons• s2p6 configuration• Not reactive, have their

octet of electrons

GHS Honors Chem

Can we determine an element simply from the Valence Electron

Configuration?

Let’s try it …

1. 3s2

2. 5s25p4

3. 4s23d6

MgTeFe

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GHS Honors Chem

Lewis Dot Structures� Lewis Dot structures are helpful in

visualizing bonding between atoms.� Dots correspond to the number of

valence electrons. These are the electrons that are involved in interactions between atoms.

� Dots are placed around the element’s symbol, 1 at a time, until pairing is necessary.

GHS Honors Chem

Lewis Dot StructuresK CaInCPSF

What about ions?02-

Br-

The number of unpaired dots corresponds to the number of bonds

that the atom can form in a compound.

GHS Honors Chem

Lewis Dot Structures