Catalyst – October (2 2 -2), 2009 Objectives  SWBAT determine the trends for atomic size and electronegativity. Catalyst  What family is Calcium in?  What period is Rb in?  Who was the first person to leave spaces for undiscovered elements on the periodic table?  How did Mosley’s periodic table differ from all of the tables that came before his?

Today’s Agenda  Catalyst  Finishing Families  More secrets of the PT: Atomic Size and Electronegativity  Exit Question

Alkali Metals Alkali metals are very reactive – even with water! Sodium + Water  EXPLOSION!EXPLOSION

Alkaline Earth Metals  Alkaline Earth metals are also very reactive  Shiny solids that are harder than Alkali metals  Alkaline Earth Metal Spotlight: CALCIUM  Calcium is essential for human life, especially in maintaining bones and teeth  Found widely in nature combined with oxygen  Abrasives in toothpaste and emery boards  Magnesium Demo!

Boron’s Group  Gallium is a silver metal that literally melts in your hand! Don’t try this yourself!

Carbon’s Group  Carbon is one of the most important elements on Earth!  There is a whole branch of chemistry dedicated to studying carbon – ORGANIC CHEMISTRY!  If you are a science major in college, you will most likely take Organic  Silicon is the second most abundant element on Earth!  Use in computer chips and solar cells  Found in quartz, sand, and glass

Nitrogen’s Group  Metals, nonmetals, and metalloids!  Nitrogen, which you breathe, can form some of the most explosive compounds known to man  Arsenic is a toxic substance that was used to treat some illnesses back in the day  Bismuth is used in fire sprinklers

Oxygen’s Group  Oxygen  We must breathe oxygen to survive…so it’s pretty important  Reacts with some of the noble gases  Sulfur  Hydrogen sulfide smells like rotten egg  Selenium  Used in solar panels because it can convert light into energy

 Fluorine (really fluoride) is added to toothpaste  Chlorine gas is a deathly green gas that was first used as a form of chemical WARFARE in WWII Halogens (Fluorine’s Group)

Noble Gases (Helium’s Group)  Noble gases do not react with other elements very often – they are already “happy”  They can be called “inert” because they don’t react  Neon is used in neon lights  Helium Voice! Helium Voice

Transition Metals  Conduct electricity  Can form different ions (We’ll learn more about ions later!)  Many found in nature – found all over the world (map on page 200)  Uses  Found in alloys, wires, plastics, etc.  Your body needs trace (small) amounts many of them

What is Atomic Size?  Atomic size is…  How big an atom is  Also known as atomic radius

Graphing Atomic Size (Radii)  Draw a line graph  X-axis: Element  Y-axis: Atomic Radii (picometers)  Part 1 – points = dots  Part 2 – points = squares

Elements and their Atomic Radii (1) ElementAtomic Radius (picometer) Hydrogen37 Lithium152 Sodium186 Potassium227 Rubidium248 Cesium265 1 picometer = 1 x m

Elements and their Atomic Radii (2) ElementAtomic Radius (picometer) Lithium152 Beryllium112 Boron85 Carbon77 Nitrogen75 Oxygen73 Fluorine72 Neon71 1 picometer = 1 x m

What trend(s) do you notice?

Atomic size DECREASES as you go across the Periodic Table Atomic size INCREAESES as you go down thePeriodic Table

Atomic Size Key Point #1: Atomic size increases as you go down the periodic table and decreases as you go left to right across the periodic table.

Practice Problems  Rank the following elements in order of increasing atomic size based on location on the periodic table (smallest to biggest) Fr, Sc, P, Pd F, As, Tl, S Magnesium, Hydrogen, Francium, Strontium Fluorine, Sulfur, Arsenic, Thallium

Practice Time! 1. T or F? Atomic size decreases as you move right across the periodic table. 2. T or F? As you move down the Periodic Table, atoms get smaller. 3. Rank the following sets of elements in order of increasing atomic size (small  big). Set A: Bh, Mn, Re, TcSet B: Sb, I, Ag, Ru Set C: Y, Ti, Sg, Ta 4. Rank the following sets of elements in order of decreasing atomic size (big  small). Set A: Cl, At, I, F, BrSet B: Te, Xe, Sn, In Set C: Rb, K, Sr, Ca

What is electronegativity?  Electronegativity is…  The ability of an atom to attract electrons to itself in a chemical bond  How much an atom wants electrons

Graphing Electronegativity  Draw a line graph  X-axis: Element  Y-axis: Electronegativity  Part 1 – points = dots  Part 2 – points = squares

Elements and their Electronegativity (1) ElementAtomic Radius (Paulings) Hydrogen2.20 Lithium0.98 Sodium0.93 Potassium0.82 Rubidium0.82 Cesium0.79 Francium0.70

Elements and their Electronegativity (2) ElementAtomic Radius (Paulings) Lithium0.98 Beryllium1.57 Boron2.04 Carbon2.55 Nitrogen3.04 Oxygen3.44 Fluorine3.98

What trend(s) do you notice?

Electronegativity Key Point #2: Electronegativity decreases as you go down the periodic table and increases as you go left to right across the periodic table.

Practice Problems  Rank the following elements in order of increasing electronegativity based on location on the periodic table (smallest to biggest) Mg, Sr, Be, Ra Cl, Si, Al, S, P Radon, Strontium, Magnesium, Beryllium Aluminum, Silicon, Phosphorus, Sulfur, Chlorine

Practice Time! 1. T or F? Electronegativity decreases as you move left across the periodic table. 2. T or F? As you move down the Periodic Table, atoms get more electronegative. 3. Rank the following sets of elements in order of increasing electronegativity (small  big). Set A: Bh, Mn, Re, TcSet B: Sb, I, Ag, Ru Set C: Y, Ti, Sg, Ta 4. Rank the following sets of elements in order of decreasing electronegativity (big  small). Set A: Cl, At, I, F, BrSet B: Te, Xe, Sn, In Set C: Rb, K, Sr, Ca

How does atomic size related to electronegativity? Key Point #3: Atomic size is indirectly related to electronegativity ELECTRONEGATIVITY ATOMIC SIZE As electronegativity increases, atomic size decreases!

Why is this relationship true?  Atoms with HIGH ELECTRONEGATIVITIES hold their electrons very close!  Sooooo, the atomic size decreases High or low electronegativity? Large or small atomic size?

Group Work Time!

Exit Question 1. Which element has atoms with the smallest size: Cl, Se, P, or F? 2. Which element has the largest electronegativity: Ag, Cu, Hg, or Zn? 3. What is the relationship between atomic size and electronegativity?