unit 4: periodic law chief of springfield periodic police department clancy wiggum

Unit 4: Periodic Law Chief of Springfield Periodic Police Department Clancy Wiggum

Castagno Chemistry Challenge IV Rules: 1) You are working as a CLASS ! 2) You will have 5minutes! 3) There are 11 questions so the highest score gets the points. POINTS Class:1 st 2pts, 2 nd 1pt, 3 rd 0pts, 4 th 0pts Questions?

Castagno Chemistry Challenge IV Sections of the periodic table are known by certain names On the blank table you are provided, match the section name to the area (lettered A, B, C, etc.). The list is on the next slide. You will have 5mins Questions?

Castagno Chemistry Challenge IV Alkaline Earth Metals Metalloids Halogens Rare Earth Metals Alkali Metals Noble Gases Transition Metals Actinides Ungrouped Metals Ungrouped non-metals Disputed

Castagno Chemistry Challenge IV Answers are on next slide

AAAAAAAAAAAA BBBBBBBBBBBB C C DDDDDDDD D D E E E E HHHHHHHHHHHH GGGGGGGG F F F F K IIIIIIII JJJJJJJJ Castagno Chemistry Challenge IV Unit 4 Periodic Law Answers: A Alkali Metals E Metalloids I Rare Earths B Alkaline Earth F Ungrouped NMs J Actinides C Transition Metals G Halogens K Disputed D Ungrouped Metals H Noble Gases Name:

Unit 4 Objectives Key terms (Periodic Law, groups, families, rows, columns, atomic radii, ionic radii, ionization energy, electron affinity, electron negativity) How the modern periodic table was developed and arranged. The properties of vertical columns and horizontal rows on the periodic table. The trends in atomic radii, ionic radii, charge, metallic character, ionization energy, electron negativity and electron affinity. Periodic means to show a pattern. The periodic table can be used as a predicative device. For a given element, its properties can be determined by its position on the periodic table. The number of periods on the periodic table is due to the number existing energy levels The number of groups on the periodic table is due to the way orbitals are filled by electrons. Elements with similar properties have similar outer energy level electron configurations.

Essential Questions Why is the Periodic Table arranged the way it is? How can the Periodic Table be used to make predictions of elemental properties? GUIDING QUESTIONS: What are the developments that led to the modern periodic table? How do vertical columns and horizontal rows on the periodic table compare? What causes Periodic variation of the properties of the elements? What are the trends in atomic radii, ionic radii, charge, metallic character, ionization energy and electron affinity?

Your Take Why are some element symbols not filled in? (P2) Where is element 113 and others? Why do they have 3 letters? Why is the f block under the periodic table? Why is there a gap between s and p? Why are atomic masses found in brackets after 84? What is an ionic charge? (P4) Why is helium floating? Why are some symbols in different colors? How long do elements last? (P6) New v Former designation? How long did it take to make? (P7) Are they adding new elements? Updating? Undiscovered elements? How do they study radioactive elements?

History I* The first recorded discovery of an element was by Hennig Brand. In an attempt to create the Philosophers Stone, he distilled human urine and eventually was left with a white substance that glowed phosphorus. The first list of non-classical (earth, air, water, fire) elements was by Antoine Lavoisier in 1789. 33 elements but the list included light and caloric, as well as hydrochloric acid Caloric is what scientists believed heat was composed of

History II* In 1817, chemist Johann Wolfgang Dobereiner found triads or groups of 3 elements with similar properties (behavior) Cl, Br, I / Ca, Sr, Ba / S, Se, Te / Li, Na, K John Newlands, working with 56 elements (23 more than Lavoisier) discovered that organizing the elements by weight resulted in a repeating pattern of properties every 8 elements Law of Octaves

History III* In 1860, more than 60 elements had been discovered. Different chemists used different values (ie: atomic mass) for the same element. This means every table is going to be different. Cannizzaro, later in the year, presented a widely accepted method to determine the atomic mass. Chemists were finally closing in on the right organization.

Mendeleev I Wrote down every known element and its properties on cards. He rearranged them according properties such as reactivity and mass looking for patterns.

Mendeleev Reenactment We can easily recreate what Mendeleev did. So we shall!

Mendeleevs Table

Mendeleev II When arranged according to atomic mass, elements with similar properties appeared at regular intervals. A repeating pattern is known as periodic.

Mendeleev IIA But does this actually work? Take a look at the periodic table. Are the elements currently arranged by mass?

Atomic Mass A quick glance at the periodic table shows mass increases most of the time. But why not all of the time?

Atomic Mass II The mass of an element is determined by a weighted average of the isotopes an element has. The most abundant isotopes skews the average towards its weight. *Hydrogen 1 is the most abundant hydrogen isotope which is why the atomic mass of hydrogen is almost exactly 1

Atomic Mass Unit* The mass of the proton, neutron, and electron are so SMALL that using them as-is is unnecessarily complex. Therefore, the three masses were converted into atomic mass units to make calculations easier

Atomic Mass Unit II* Proton mass: 1.672 x 10 -27 kg Proton a.m.u.: 1.007 Neutron mass: 1.674 x 10 -27 kg Neutron a.m.u.: 1.008 Electron mass: 9.109 x 10 -31 kg Electron a.m.u.: 0.000548

Average Atomic Mass I* In order to calculate the mass of an element that is seen on the periodic table, we utilize the mass of every isotope in a.m.u. We also need the relative percent abundance of each isotope.

Average Atomic Mass II There are numerous isotopes of carbon but C-12 and C-13 are the most abundant. Isotope% AbundanceMass (amu) Carbon 110.0011.0114 Carbon 1298.912.0000 Carbon 131.1013.0033 Carbon 140.0014.0032

Average Atomic Mass III This means our weighted average calculation can ignore C-11 and C- 14. A normal average of C-12 and C-13 would be (12.0000 + 13.0033) / 2 = 12.50165 According to the periodic table, the mass of carbon is 12.011

Average Atomic Mass IV Our average calculation must take into account PERCENT abundance. 12.0000 * 98.9% = 11.868 13.0033 * 1.1% = 0.143 Now we add the answers together 11.868 + 0.143 = 12.011

Average Atomic Mass V The mass on the periodic table refers to 6.02 x 10 23 atoms. Also known as 1 mole. So atomic mass = molar mass of an element Quantities other than 1 mole can be solved proportionally. 2 moles = 2x molar mass 0.33 moles = 0.33x molar mass

Mendeleev III Published his first table in 1869. Iodine Mass is less than tellerium. Because it behaved like F, Cl, and Br, he placed it with those elements instead. He predicted the existence of 3 elements in 1871. By 1886, all 3 (Sc, Ga, and Ge) were discovered with properties similar to those he predicted.

A Summary of Mendeleev* Unknown to Mendeleev, Lothar Meyer published his own periodic table. Despite the obvious lack of the Noble Gases (they had not been discovered yet), Mendeleevs table is a good predictor of to-be-discovered elements properties. Mendeleev initially resisted the placement of Noble Gases into the table. It was possible to add those elements without disturbing the trends of all the others. This is why Mendeleev gets the credit his periodic table was a predictive tool.

Nonetheless* The Iodine-Tellurium problem showed that arranging the elements by mass is not good enough. Scientists searched for a better way to arrange the elements without having to pick and choose what elements go where. In other words, there should be characteristic about an atom (element) that takes the choice of placement out of the scientists hands.

Henry Moseley Moseley worked with Ernest Rutherford analyzing the nucleus of atoms. He found the patterns of chemical properties fit better when elements were arranged by the number of protons in the nucleus.

Periodic Law Moseleys work confirmed that tellerium (an atom with 52 protons) should be placed before iodine (53 protons). Mendeleevs principle of periodicity was rewritten into what is now known as periodic law The physical and chemical properties of the elements are periodic functions of their atomic numbers.

The Modern Table In the nearly 150 years since Mendeleev, chemists have discovered (or created) over 50 new elements. These new elements were inserted into the periodic table based off of the atomic number (number of protons in the nucleus). As Mendeleev predicted, the new elements fit neatly according to Periodic Law.

The Noble Gases The Noble Gases were a significant find. Helium was discovered first (1868), but not found on earth until 1895. Argon was found by Lord Rayleigh and Sir William Ramsay in 1894. To fit this new class of elements onto the periodic table, Ramsay proposed a new group. Ramsay also discovered Krypton and Xenon, though did not discover Radon.

The Lanthanides and Actinides Lanthanides The top row of the f block. The elements are very similar in physical and chemical properties they were difficult to separate and identify. Actinides The bottom row of the f block. Composed of all radioactive elements, most of which are manmade. The reason they are cut and pasted below the other elements is to save space.

Periods and Blocks

Hydrogen and Helium Hydrogen does not fit with any specific group. It is placed over Group 1 because it has 1 outer electron. It does not fit in terms of reactivity or other properties. Helium All Noble Gases have 8 outer electrons, Helium has 2. It is placed over Group 18 (8) because of its chemical stability.

The s Block Consists of two groups All are metals Group 1 Alkali Metals Most reactive metals known Not found isolated in nature Can be cut with a kitchen knife Group 2 Alkaline-Earth Metals Less reactive than alkalis Harder, denser, and stronger than alkalis Also not found isolated in nature

The d Block This is the largest block, right in the middle of the table. Transition Metals Typical metallic properties Good conductors of heat Good conductors of electricity Typically less reactive than alkali and alkaline-earth metals Some are extremely nonreactive (Pd, Pt, Au)

The p Block

The p Block II No specific group names for B, C, N, and O groups. Halogens (Group 17 (7)) Most reactive nonmetals Form compounds known as salts. Noble Gases (Group 18 (8)) Least reactive elements All have full outer shells of electrons Metalloids Not a group, but these are elements with intermediate conductive properties.

The f Block Lanthanides (Top row) Shiny metals Similar reactivity to alkaline-earth metals Actinides (Bottom row) All radioactive Th, Pa, U, and Np have all been found naturally on earth.

Synthetic Elements* Every element up to Californium exists naturally on earth. Tc, Pm, Np, Pu, Am, Cm, Bk, and Cf are produced in significant quantities by laboratories but natural nuclear reactions produce these elements in minute quantities in earths crust. Every element from Einsteinium and on are purely synthetic.

Where am I? Challenge #2 There will be clues on the following slides and you must pick what area of the periodic table they are found in. The areas are located on pieces of paper throughout the classroom so just stand by your location.

Where am I? Locations Alkali Metals Alkaline Earth Metals Transition Metals Other (nongrouped) Metals Lanthanides Actinides Nonmetals (nongrouped) Halogens Noble Gases Metalloids While there is a guarantee everything WILL BE USED ONCE, there is no guarantee on the maximum.

Where am I #1? I am a metal often used in magnets. Despite the fact Im not rare at all I am considered to be rare earth.

Where am I #2?

Where am I #3? The first element discovered that has an organic origin. In other words, I was discovered in human urine.

Where am I #4?

Where am I #5? My reactions with water are legendary. I contain elements necessary for batteries and life. Extremely soft for being solid and float on water.

Where am I #6?

Where am I #7? I do not like to be bothered. My appetite for electrons is nonexistent because I am always full.

Where am I #8?

Where am I #9? I conduct electricity but am not used for this purpose. I can be molded into pipes but am no longer used for this purpose. If I have a stomach ache, you will use me to feel better.

Where am I #10?

Where am I #11? My similarly named cousin lost his status but Ive had mine for around 70 years now. You can buy me in a store, bringing radiation into your home to protect against fires.

Where am I #12?

Where am I #13? Titans and wolfs and the country of Argentina (plus ALL of Scandinavia) all belong to me.

Where am I #14?

Where am I #15? My neighbors love to party and set off fireworks when they drink water. I just prefer to relax and let it bubble around me.

Where am I #16?

Where am I #17? I know that I am definitely not what I am not but I am also definitely sure I am not quite sure what I am.

Where am I #18?

Where am I #19? There is one of every type of element in my group. I am the only one like it.

Where am I #20?

Challenge #2 Answers Answers on next slide

Challenge #2 Answers 1) Lanthanide 2) Transition 3) Nonmetal 4) Alkaline Earth 5) Alkali 6) Metalloid 7) Noble Gas 8) Ungrouped Metal 9) Ungrouped Metal 10) Noble Gas 11) Actinide 12) Halogen 13) Transition 14) Alkali 15) Alkaline Earth 16) Nonmetal 17) Metalloid 18) Lanthanide 19) Halogen 20) Actinide

Mini Review What names are used for the following groups? 1) Group 17 Halogens 2) Group 2 Alkaline-earth metals 3) Group 18 Noble Gases 4) Group 1 Alkali Metals 5) Groups 3 12 Transition Metals

Mini Review II Arrange the metals in terms of reactivity from highest the lowest: Transition, Alkali, Alkaline, Lanthanide Alkali, Alkaline/Lanthanide, Transition For the following element, identify the block, period, group #, group name (if applicable), element name, element type (ie: metalloid), and reactivity (high or low) [He]2s 2 2p 5 p-block, 2 nd period, Group 17, Halogens, fluorine, nonmetal, high reactivity [Ar]4s 2 3d 10 d-block, 4 th period, Group 12, transition, zinc, metal, low

Periodic Properties Thanks to Moseley and Mendeleev, the elements are arranged in such a way that their properties appear in known intervals. Interestingly enough, these properties exhibit trends across a period (row) or down a group (column).

Property 1: Valence Electrons When chemicals react, only electrons are lost, gained, or shared. For any element, there are specific electrons that will interact: valence electrons. Main Group Trend s and p block Group 1 1 valence electron (xs 1 ) Group 2 2 valence electrons (xs 2 ) Group 1 3 3 valence electrons (xs 2 xp 1 ) Group 1 8 8 valence electrons (xs 2 xp 6 ) a full octet

Properties 2 - 6 2) Atomic Radius 3) Ionization Energy 4) Electron Affinity 5) Ionic Radii 6) Electronegativity Get into your lab groups and choose a property.

Property 2: Atomic Radius one-half the distance between the nuclei of identical atoms bonded together

Atomic Radius - Trends Group Trend Main groups General INCREASE in atomic radius down a group Period Trend Main groups General DECREASE in atomic radius across a group Why? The positive charge increases, but the electrons have the same energy

Property 3: Ionization Energy the energy required to remove an electron from a neutral atom Example Na + energy Na + + e -

Ionization Energy - trends Group Trend Main Group General DECREASE in ionization energy down a group Why? The electrons are further from the nucleus, easier to remove Period Trend Main Group General INCREASE in ionization energy across a group Why? The charge in the nucleus increases, while the electrons have the same energy

Property 4: Electron Affinity the energy change that occurs when an electron is acquired by a neutral atom Example Na + e - Na - + energy

Electron Affinity - trends Group Trend Main Group General INCREASE in electron affinity down a group Why? It is harder to add an electron to the neutral atom Period Trend Main Group General INCREASE in ionization energy across a group Halogens have the greatest electron affinity

Property 5: Ionic Radii Cation A positive ion Anion A negative ion The ionic radius is simply the radius of an ion.

Ionic Radii- trends Group Trend Main Group General INCREASE in ionic radii down a group Why? Cations the atom is simply bigger Anions greater negative charge Period Trend Cations General DECREASE as the positive charge increases Anions General DECREASE as the negative charge decreases

Property 6: Electronegativity a measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound Think of it as how much an atom will share.

Electronegativity trends Group Trend Main Group General DECERASE in electronegativity down a group Period Trend Main Group General INCREASE in electronegativity across a group Note: Alkali metals are the least electronegative group Halogens are the most electronegative group

unit 4: periodic law chief of springfield periodic police department clancy wiggum

Documents

slide slide

modern periodic table

periodic variation

periodic means

periodic law answers

blank table

ionic radii

atomic radii