Chemical Families
Chemistry 5(B)
Chemical Families
Lesson Objectives
• Identify and explain the properties of chemical families in
the periodic table
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Alkali metals
Alkaline earth metals
Transition metals
Halogens
Noble gases
The Periodic Table
• Periodic table – table that displays the elements in order of
increasing atomic number and organizes them according to
chemical properties
• Elements arranged in a periodic pattern
• Behavioral trends of an element can then be predicted by
knowing its position on the table
The Periodic Table
Periods and Groups
• Periodic table is arranged in
– Periods – rows on the periodic table
– Groups – columns on the periodic table
• Also called families, since elements in groups share similar chemical
properties
Numbering Groups
• Groups are numbered 1–18 or 1–8 with A/B notation
– Tall columns are notated as “A”
• Main group elements
– Short columns are notated as “B”
1A
2A
3B
4B
5B
6B
7B
8B
1B
Main Group Elements
2B 3A
4A
5A
6A
7A
8A
Chemical Families
• Family names
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Group 1A –– alkali metals
Group 2A –– alkaline earth metals
Group 7A –– halogens
Group 8A –– noble gas
Group 1–8B –– transition metals
1A
2A
3B
4B
5B
6B
7B
8B
1B
2B 3A
4A
5A
6A
7A
8A
Decoding the Periodic Table
• Arrangement of elements on periodic table help predict
physical and chemical properties including
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Physical state
Boiling, melting, or freezing point
Density
Metallic and nonmetallic character
Reactivity
Likelihood of gaining or losing electrons
Valence – number of electrons in the atom’s valence or outermost energy
level
Metals, Nonmetals, and Metalloids
• Step-wise line that begins at the element boron and moves
downward in a zigzag pattern divides the table
– Metals are to the left of the line
– Nonmetals are to the right of the line
– Along the line are the metalloids
• Possess properties of both metals and nonmetals
Metalloids
Metallic and Nonmetallic Character
• Metals tend to lose electrons to form cations
– Cations – positively charged particles
– Other properties of metals
• Lustrous, good conductors, malleable, and ductile
• Nonmetals gain electrons to form anions
– Anions – negatively charged particles
– Other properties of nonmetals
• Many are gases at room temperature, solids are usually brittle, and are
typically poor conductors
Chemical Properties
• Elements in the same group will have similar chemical
properties
• Group number of group A elements equals the number of
valence electrons
– Valence electrons – electrons in the valence or outermost energy
level, which are most likely to be lost, gained, or shared
– Determines the oxidation number of an element
• Positive if electrons are lost
– Positive charge equals the number of electrons lost
• Negative if electrons are gained
– Negative charge is equal in magnitude to the number of electrons gained
Chemical Properties
• Reactivity is determined by the ability to gain, lose, or
share electrons in order to achieve an octet
– Octet – eight electrons in the valence energy level
– Noble gases naturally have an octet
• Extremely low reactivity
– Other groups attempt to achieve octets by gaining, losing, or
sharing electrons
• Higher reactivity
– Types of elements involved in the reaction will determine how
the octet is achieved
• Metals tend to lose electrons when reacting with nonmetals
• Nonmetals tend to gain electrons when reacting with metals and share
electrons when reacting with other nonmetals
Noble Gases
• Noble gases
8A
18
– Gases at room temperature
– Relatively inert
• Have full valence shells
• Typically don’t form ions
By Felix Burton (Flickr) [CC-BY-2.0]
Halogens
• Halogens
– Highly reactive nonmetals
• Seven valence electrons
– One electron away from having an octet
• Gain one electron to achieve octet
– Ions have -1 charge
• Very electronegative
– Electronegative – possessing the ability to acquire electrons
readily
– Form ionic bonds by accepting electrons from metals
– Form covalent bonds by sharing electrons with other
nonmetals
– Combine with H+ to form acids
7A
17
Alkaline Earth Metals
• Alkaline earth metals
– Highly reactive metals
• Two valence electrons
– Two electrons away from having an octet
• Loses two electrons to attain octet
– Ions have +2 charge
– Form oxides by combining with oxygen
– Form ionic bonds with nonmetals, creating salts
– Combine with OH– to form bases
2A
2
Alkali Metals
• Alkali Metals
– Highly reactive metals
• One valence electron
– One electron away from having an octet
• Lose one electron to attain an octet
– Ions have +1 charge
– Form oxides by combining with oxygen
– Form ionic bonds with nonmetals, creating salts
– Combine with OH– to form strong bases
1A
1
Transition Metals
• Groups 1–8B are collectively called the transition metals
– Transition in oxidation numbers
– Form different compounds with nonmetals as a result of
variance in charges
– Less reactive than alkali metals or alkaline earth metals
3B
4B
5B
6B
7B
3
4
5
6
7
8B
8
9
1B
10
11
2B
12
Chemical Families
Lesson Objectives
• Identify and explain the properties of chemical families in
the periodic table
–
–
–
–
–
Alkali metals
Alkaline earth metals
Transition metals
Halogens
Noble gases