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

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: Gas: Solid: Hg and Br 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 Nonmetals 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

State the charge of the following elements as ions Fluorine Phosphorus Beryllium Aluminum