Chapter 5: The Periodic Table 5.1 Organizing the elements 5.2 The Modern Periodic Table 5.3 Representative groups

Organization of the Elements Section 5.1 Organization of the Elements

Search for Order 1750 only 17 elements known 1789 Antoine Lavoisier grouped known elements (4 groups) Metals Non-metals Gases Earths Next 80 yrs scientists looked for better way to classify known elements

Mendeleev’s Periodic Table 1869….Dmitri Mendeleev (Russian teacher and chemist) organized known elements while playing solitaire Made deck of cards with elements Listed name, mass and properties Paid attention to how elements reacted in chemical reactions

Mendeleev’s Periodic Table Strategy for organization: What did he look at? chemical properties physical properties atomic mass density color melting point Valence electrons (sec 5.3)

Mendeleev’s Proposal Elements arranged in rows based on increasing mass. Elements with similar properties are in same column. Chart was a Periodic Table - arrangement of elements in columns based on a set of properties that repeat.

Mendeleev’s Prediction Table incomplete– elements not yet discovered Left spaces in table for undiscovered elements Good models allow for predictions to be made based on model Used properties of nearby elements to predict properties of unknown elements

He called this element eka-Aluminum. Later it was renamed Gallium after its discovery in 1875

Evidence Supporting Mendeleev’s Table Close match between Mendeleev’s predictions and the actual properties of new elements showed how useful table was. Ex. Discovery of: Aluminum, Gallium, Scandium, and Germanium http://www.iteachbio.com/Chemistry/Chemistry/The%20Periodic%20Table.mov

The Modern Periodic Table YOU NEED 3 DIFFERENT COLORED PENCILS Section 5.2 The Modern Periodic Table The Elements by Tom Lehrer

The Modern Periodic Table “Periodic” - Repeating patterns Listed in order of increasing number of protons (atomic #) Properties of elements repeat Periodic Law- when elements arranged by increasing number of protons, properties repeat in pattern

Columns in the Periodic Table -vertical (up & down) -called groups or families -#ed 1-18 or 1A through 8A -elements in same family have similar properties

Rows in the Periodic Table -horizontal (left – right) -called a period -properties change greatly across period -first element in period is very active metal -last element in most periods is noble gas -7 periods (number them on your periodic table)

6 C Carbon 12.01 For example: Carbon has atomic # 6 Element Key Important information about an element is given in each square of the periodic table: its atomic number chemical symbol element name average atomic mass 6 C Carbon 12.01 For example: Carbon has atomic # 6 (or has 6 protons), an average atomic mass of 12.01 and a symbol of C

Two isotopes of copper 72% copper-63 28% copper-65 Atomic Mass Two isotopes of copper 72% copper-63 28% copper-65 Makes the average 63.56 amu

Determining Average Atomic Mass

Metals Most solids (Hg is liquid) Luster – shiny. Ductile – drawn into thin wires. Malleable – hammered into sheets. Conductors of heat and electricity. Include transition metals – “bridge” between elements on left & right of table

Non-Metals Properties are generally opposite of metals Poor conductors of heat and electricity Low boiling points Many are gases at room temperature Solid, non-metals are brittle (break easily) Chemical properties vary

Metalloids stair-step pattern Have properties similar to metals and non-metals Ability to conduct heat and electricity varies with temp Better than non-metals but not metals

Variation Across a Period: Left to Right Physical and Chemical properties Atomic size decreases Metallic properties decrease Ability to lose an electron decreases Ability to gain electrons increases

Representative Groups Section 5.3 Representative Groups Hip Hop Classroom The Elements

What are Valence electrons? outermost e-’s Responsible for chem props Elements in same group… same # of VE ALL atoms want full outer energy level (usually 8 VE) To get full outer energy level, some elements: lose e- (metals) gain e- (non-metals) share electrons (some non-metals & metalloids)

Introducing the ten major groups (families) on the modern Periodic Table:

Alkali Metals - 1 valence electron (VE) potassium - 1 valence electron (VE) - soft, silver-white, shiny metals never found pure most reactive metals Reactivity increases down group reactivity increases

Label the Alkali Metals to your PT

Alkaline Earth Metals - 2 VE - not as reactive as alkali metals magnesium - 2 VE - not as reactive as alkali metals often mixed with Al forms strong/light weight alloys

Alkaline Earth Metals Magnesium Calcium Used to make steel (light metal w/o losing strength) photosynthesis (chlorophyll) Calcium bones & teeth Chalk, limestone, pearls, plaster

Label the Alkaline Earth Metals to your PT

Boron Family -3 VE Boron Hard/brittle never found pure in nature in borax...used to make detergents & cosmetics

Boron Family 13 Al Aluminum 26.98 Aluminum most abundant metal in earth’s crust important metal for industry light, strong, slow to corrode 13 Al Aluminum 26.98

Label the Boron Family on your PT

Carbon Family 4 VE Can gain 4 e-, lose 4 e-, or share e- silicon 4 VE Can gain 4 e-, lose 4 e-, or share e- Most compounds in body contain C Si 2nd most abundant element in Earth’s crust Si used to tip saw blades

Label the Carbon Family on your PT

Nitrogen Family 5 VE Tend to gain 3 e- N and P used in fertilizers Arsenic 5 VE Tend to gain 3 e- N and P used in fertilizers P on tips of matches

Label the Nitrogen Family on your PT

Oxygen Family 6 VE Tend to gain 2 e- O very abundant element sulfur Oxygen Family 6 VE Tend to gain 2 e- O very abundant element S used in fertilizers O needed for digestion

Label the Oxygen Family on your PT

Halogen Family (“salt-former”) -7 VE -most active nonmetals -never found pure in nature -react with alkali metals easily (forms salts) -F most active halogen

F compounds in toothpaste Cl kills bacteria Halogens cont… bromine F compounds in toothpaste Cl kills bacteria I keeps thyroid gland working properly

Label the Halogen Group on your Periodic Table

The Noble Gases (Inert Gases) Neon - non-reactive outermost e- shell is full (8 VE) In “neon” lights -in earth’s atmosphere (less than 1%)

Label the Noble Gases on your Periodic Table

Transition Metals ductile, malleable, conductors mercury Almost all solids at room temp (Hg exception) ductile, malleable, conductors VE varies Less Reactive than Groups 1 & 2 Fe, Co, and Ni produce magnetic field

Label the Transition Metals on your periodic table

Rare Earth Elements Lanthanide series (period 6) uranium Lanthanide series (period 6) Actinide Series (period 7) Some radioactive Separated from table to make easy to read/print silver, silvery-white, or gray metals. Conduct electricity

Label the Lanthanide Series on your PT

Label the Actinide Series on your PT

You may watch more videos about the elements at: http://www.periodicvideos.com/ or sing along at: http://www.youtube.com/watch?v=zGM-wSKFBpo&feature=related elemental funkiness - Mark Rosengarten hip hop classroom