Download Periodic Trends

Periodic Trends
Arrangement
• Elements are arranged according to atomic
number
– Number of protons
– Not atomic mass
Group/Family
• Vertical column in the periodic table
• 18 groups
• Elements in same group
– Same physical and chemical properties
• Same number of electrons in last energy level
• Example:
– Group 18
• All gases
• All unreactive
• Same number of electrons in last energy level
Valence electrons
• Electrons in the last energy level of an atom
– Involved in chemical reactions and bonding
– Coincides with the unit’s place on the group
number except for Groups 3 - 12
• Group 1: 1 valence electron
• Group 2: 2 v.e.
• Group 18: 8 v.e. except for He
Lewis Dot Diagram
• Shows the number of valence electrons in a
neutral atom
• Each dot represents 1 valence electron
Lewis Structure Practice
Carbon
Hydrogen
Calcium
Oxygen
Metals
• Left and middle of periodic table except H
• Properties:
– Ductile: drawn into a wire
– Malleable: hammered into thin sheets
– Good conductors of heat/electricity
– Luster: shine
– Solid at room temperature (except for Hg)
Nonmetals
• Far right side of periodic table
• Properties
– Brittle: break when hammered
– Lack luster
– Poor conductors
– Solid or gas at room temperature (except Br)
Metalloids (Semi-metals)
• Along the black line that divides metals and
nonmetals
• Have properties of both metals and nonmetals
3 states of matter
• Liquid:
– Hg and Br
• Gas:
– all the noble gases (group 18)
– and O, F, N, H, Cl
• Solid:
– rest of the elements in the periodic table
Ions
• Charged elements
• Metals
– Positive ions (lose electrons) to have a complete
valence shell
Magnesium  Mg2+
• Nonmetals
– Negative ions (gain electrons) to fill valence shell
– Nitrogen  N3-
Relationship between charge and
group
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Group 1= +1
Group 2= +2
Group 13= +3
Group 14 = =/- 4
Group 15= -3
Group 16= -2
Group 17 = -1
Group 18= 0
State the charge of the following
elements as ions
Fluorine
Phosphorus
Beryllium
Aluminum