The Periodic Tablel Arrangement of the known elements based on atomic number and chemical and physical properties.l Dividedinto three basic categories: l Metals l Nonmetals l Metalloids
Basic OrganizationThe periodic table is organized by:l Atomic structurel Atomic numberl Chemical and Physical Properties
Uses of The Periodic TableThe periodic table is useful in predicting:l chemical behavior of the elementsl trendsl properties of the elements
Atomic Structure Reviewl Atoms are made of protons, electrons, and neutrons.l Elements are atoms of only one type.l Elements are identified by the atomic number (# of protons in nucleus).
Energy Levels Reviewl Electronsare arranged in a region around the nucleus called an electron cloud. Energy levels are located within the cloud.l At least 1 energy level and as many as 7 energy levels exist in atoms.
Energy Levels Reviewl Electrons in levels farther away from the nucleus have more energy.l Inner levels will fill first before outer levels.
Energy Levels & Valence Electrons l Energy levels hold a specific amount of electrons: l 1stlevel = up to 2 l 2nd level = up to 8 l 3rd level = up to 8 (first 18 elements only)
Energy Levels & Valence Electronsl The electrons in the outermost level are called valence electrons. l Determine reactivity - how elements will react with others to form compounds l Outermost level does not usually fill completely with electrons
Using the Table to Identify Valence Electronsl Elements are grouped into vertical columns because they have similar properties.l These are called groups or families.l Groups are numbered 1-18.
Using the Table to Identify Valence Electronsl Group numbers can help you determine the number of valence electrons: l Group 1 has 1 valence electron. l Group 2 has 2 valence electrons. l Groups 3–12 are transition metals and have 1 or 2 valence electrons.
Using the Table to Identify Valence Electrons cont.l Groups 13–18 have 10 fewer than the group number. For example: l Group 13 has 3 valence electrons. l Group 15 has 5 valence electrons. l Group 18 has 8 valence electrons.
Elements & Reactivityl Reactivity is a chemical property that determines how elements will react with others to form compounds.
Elements & Reactivityl What makes an element reactive? ● Number of valence electrons each atom has ● When outer levels are full, atoms are stable. ● When they are not full, they react: ● gain, lose, or share 1 or 2 electrons.
Elements & Reactivityl The most reactive metals are the elements in Groups 1 and 2. l Elements in Group 1 need seven more electrons to fill their outer level. l Elements in Group 2 need six more electrons to fill their outer level.l Thesegroups are known as the “givers” because they easily give up their valence electrons to make a compound.
Elements & Reactivityl The most reactive nonmetals are the elements in Groups 6 and 7. l Elements in Group 6 only need two more electrons to fill their outer level. l Elements in Group 7 only need one more electron to fill their outer level.l These groups are known as the “takers” because they easily receive valence electrons to make a compound.
Groupsl Groups run vertically in the periodic table.l They are numbered from 1–18.l Elements in the same groups have the same number of valence electrons in the outer energy level.l Grouped elements behave chemically in similar ways.
Group 1: Alkali Metalsl Contains: Metalsl Valence Electrons: 1l Reactivity: Very Reactivel Properties: l solids l soft l react violently with water l shiny l low density
Group 2: Alkaline-Earth Metalsl Contains: Metalsl Valence Electrons: 2l Reactivity: very reactive, but less reactive than alkali metals (Group 1)l Properties: l Solids l Silvercolored l More dense than alkali metals
Groups 3-12 Transition Metalsl Contain: Metalsl Valence electrons: 1 or 2l Reactivity: less reactive than alkali and alkaline-earth metalsl Properties: l Higherdensity l Good conductors of heat and electricity
Groups 3-12 Transition Metals Below Main Tablel Contain: The Lanthanide and Actinide Series l These two rows are pulled out of sequence and placed below the main table to keep the table from being too wide. l Lanthanides are #’s 58–71. l Actinides are #’s 90–103.
Groups 3-12 Rare Earth Elements ~ Lanthanidesl Lanthanides follow the transition metal # 57 Lanthanum in Period 6.l Valence electrons: 3l Reactivity: Very reactivel Properties: ● High luster, but tarnish easily ● High conductivity for electricity ● Very small differences between them
Groups 3-12 Rare Earth Elements ~ Actinidesl Actinides follow the transition metal # 89 Actinium in Period 7l Valence electrons: 3 (but up to 6)l Reactivity: unstable l All are radioactive l Most made in laboratories
Metalloidsl A zig-zag line that separates metals from metalloidsl Elements from Groups 13–17 contain some metalloids.l These elements have characteristics of metals and nonmetals.
Group 13: Boron Groupl Group 13: Boron Groupl Contains: 1 metalloid and 4 metalsl Valence Electrons: 3l Reactivity: Reactivel Other shared properties: l Solid at room temperature
Group 14: Carbon Groupl Contains: 1 non-metal, 2 metalloids, and 3 metalsl Valence Electrons: 4l Reactivity: Variesl Other shared properties: l Solid at room temperature
Group 15: Nitrogen Groupl Contains: 2 non-metals, 2 metalloids, and 1 metall Valence electrons: 5l Reactivity: Variesl Other shared properties: l All but N are solid at room temperature
Group 16: Oxygen Groupl Contains: 3 non-metals, 1 metalloid, and 2 metalsl Valence Electrons: 6l Reactivity: Reactivel Other shared properties: l All but O are solid at room temperature.
Groups 17 : Halogensl Contain: Nonmetalsl Valence Electrons: 7l Reactivity: Very reactivel Other shared properties ● Poor conductors of electric current ● React violently with alkali metals to form salts ● Never found uncombined in nature
Group 18 Noble Gasesl Contains: Nonmetalsl Valence Electrons: 8 (2 for He)l Reactivity: Unreactive (least reactive group)l Other shared properties: l Colorless, odorless gases at room temperature l Outermost energy level full l All found in atmosphere
Hydrogen Stands Apartl H is set apart because its properties do not match any single group.l Valence electrons: 1l Reactivity: very, but loses the 1 electron easilyl Properties: l Similar to those of non-metals rather than metals
Periodsl Periods run horizontally across the Periodic Tablel Periods are numbered 1–7l All the elements in a period will have the same number of energy levels, which contain electrons. Examples: l Period 1 atoms have 1 energy level. l Period 2 atoms have 2 energy levels. l Period 5 atoms have 5 energy levels.
Periods Continuedl Movingfrom left to right across a period, each element has one more electron in the outer shell of its atom than the element before it.l This leads to a fairly regular pattern of change in the chemical behavior of the elements across a period.