UNIT 6: PERIODIC TABLE How has the Periodic Table evolved overtime? How is the Periodic Table arranged? What are properties and locations of metals and nonmetals? Are there patterns (trends) within the Periodic Table? How can we explain the patterns (trends) of the Periodic Table? Honors Chemistry Ms. Argenzio John Newlands, an English scientist listed all the known elements by their atomic masses Elements with the least amount of mass were first followed by elements with greater masses 1869 Dimitri Mendeleev, Russian scientist organized elements according to their atomic mass and properties Developed a chart with columns and rows Columns called family or group Families contained elements with similar properties Each row is called period Left to right across a period elements increase in atomic mass Mendeleev believed there were more elements that would be added and left places in his chart empty Lists elements according to their atomic number Still used columns called families which consist of elements with similar properties Still uses rows called periods. Elements increase by 1 moving from left to right. Periodic table lists 118 element. May need to be revised as new elements are discovered. MODERN PERIODIC TABLE Periodic Table Geography The horizontal rows of the periodic table are called PERIODS. The vertical columns of the periodic table are called GROUPS, or FAMILIES. The elements in any group of the periodic table have similar physical and chemical properties! Periodic Law When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemical properties. The periodic table is the most important tool in the chemists toolbox!mistry/periodictableofelements/zoom.wemlwww.brainpop.com/science/matterandche mistry/periodictableofelements/zoom.weml AIM: What are the properties and locations of metals and nonmetals? PROPERTIES: Ductile: able to be pulled into a wire Malleable: able to be hammered into shapes Brittle: will shatter into pieces if struck Luster: shiny Dull: not shiny AIM: What are the properties and locations of metals and nonmetals? - METALS Location: to the left of the staircase State(s) the metals exist as at STP: all solids except Hg liquid Properties: Malleable- low ionization energy Ductile- low electronegativity Has luster- lose electrons to form pos Good conductors ions with smaller radii High MP, BP MELPS HELP!!!!!!!!!!! AIM: What are the properties and locations of metals and nonmetals - NONMETALS Location: to the right of the staircase State(s) the metals exist as at STP: all solids except H, He, N, O, F, Cl, Group 18- Gases; Br - liquid Properties: Brittle - high ionization energy Dull - high electronegativity Low MP, BP - gain electrons to form neg Poor conductors ions with larger radii AIM: What are the properties and locations of metals and nonmetals TRANSITION METALS Transition metals are generally located in groups 3 to 12. They form colored ions. When mixed with water they produce colored _ aqueous solutions. AIM: What are the properties and locations of metals and nonmetals METALLOIDS Metalloids are located on the staircase between metals and nonmetals. They display some metallic properties and some nonmetallic properties. There are six metalloids List them below and make sure to put their name and symbol B, Si, Ge, As, Sb, Te AIM: What are the properties and locations of metals and nonmetals NOBLE GASES Noble gases are located in group 18. They have a full valence shell and are therefore very stable. They are not very reactive. AIM: Are there patterns (trends) within the Periodic Table? IONIZATION ENERGY Amount of energy needed to remove the most loosely bound electron from a neutral gaseous atom. (Listed in Table S) PERIOD TREND Ex) List the ionization energies for the following elements in period 2 What do you notice is happening to the ionization energies when looking across the period from left to right? increasing Values from left to right across a period increase ElementLiBF Ionization Energy GROUP TREND Ex) List the ionization energies for the following elements in group 2 What do you notice is happening to the ionization energies when looking down a group from top to bottom? decreasing In a group ionization energy decrease. ElementIonization Energy Be900 Sr549 Ba503 AIM: Are there patterns (trends) within the Periodic Table? ATOMIC RADIUS Atomic radius is half the distance between nuclei of identical atoms bonded together. (Basically tells the size of a neutral atom. Listed in Table S) PERIOD TREND Ex) List the atomic radius for the following elements in period 2 What do you notice is happening to the atomic radius when looking across the period from left to right? decreasing Values from left to right across a period decrease ElementLiBF Atomic Radius GROUP TREND Ex) List the atomic radius for the following elements in group 2 What do you notice is happening to the atomic radius when looking down a group from top to bottom? increasing In a group atomic radius increase. ElementAtomic Radius Be99 Sr190 Ba206 AIM: Are there patterns (trends) within the Periodic Table? ELECTRONEGATIVITY The electronegativity value of an atom is a measure of its attraction for electrons when bonded to another atom. Electronegativity values are listed in Table S. PERIOD TREND Ex) List the electronegativity values for the following elements in period 2 What do you notice is happening to the electronegativity when looking across the period from left to right? increasing Values from left to right across a period increase ElementLiBF Electronegativity GROUP TREND Ex) List the electronegativity values for the following elements in group 2 What do you notice is happening to the electronegativity when looking down a group from top to bottom? decreasing In a group atomic radius decrease. ElementAtomic Radius Be1.6 Sr1.0 Ra0.9 AIM: Are there patterns (trends) within the Periodic Table? VALENCE ELECTRONS Valence electrons are electrons in the outer energy level of an atom PERIOD TREND Using your Periodic Table as a reference, list the # of valence electrons for period 2 elements in the order below) What is happening to the number of valence electrons going from left to right across a period? Increases Going from left to right across a period the number of valence electrons increase. ElementLiBeBCNOFNe Valence e GROUP TREND Using your Periodic Table as a reference, list the # of valence electrons for group 2 elements in the order below) What is happening to the number of valence electrons as you move down a group from top to bottom? Stay the same From top to bottom in a group the number of valence electrons remains the same. Element# of valence electrons Be2 Mg2 Ca2 Sr2 Ba2 Ra2 AIM: Are there patterns (trends) within the Periodic Table? PRINCIPLE ENERGY LEVELS The orbitals in an atom form a series of energy levels in which electrons may be found. Each electron in an atom has its own distinct amount of energy that corresponds to the energy level that it occupies. Electrons can gain or lose energy and move to different levels. PERIOD TREND Using your Periodic Table as a reference, list the # of principle energy levels for period 2 elements in the order below) What is happening to the number of principle energy levels going from left to right across a period? nothing Going from left to right across a period the number of principle energy levels remains the same. ElementLiBeBCNOFNe Energy level GROUP TREND Using your Periodic Table as a reference, list the # of principle energy levels for group 2 elements in the order below) What is happening to the number of principle energy levels as you move down a group from top to bottom? Increasing From top to bottom in a group the number of principle energy levels increases. ElementAtomic Radius Be2 Mg3 Ca4 Sr5 Ba6 Ra7 AIM: Are there patterns (trends) within the Periodic Table? METALLIC CHARACTER Most known elements are metals. Most active metals are located in groups 1 and 2. In any group on the Periodic Table the metallic properties of the elements increase from top to bottom. AIM: Are there patterns (trends) within the Periodic Table? IONIC RADIUS Atoms gain or lose electrons to become charged particles called ions. Metals tend to lose their valence electrons in chemical reactions to become positive ions. Nonmetals tend to gain electrons in chemical reactions and become negative ions. As these atoms gain or lose electrons, they complete an octet of valence electrons. Ionic radius is the distance from the nucleus to the outer principle energy level of the ion. AIM: Are there patterns (trends) within the Periodic Table? IONIC RADIUS When a metal loses its valence electrons and becomes positively charged it loses an energy level, its radius decreases. When a nonmetal gains an electron and becomes negatively charged its radius increases. **The ionic radius of metals is smaller than the radius of the original atom. The radii of nonmetallic ions are larger than those of the original atoms**. Effect of atomic structure on Periodic Trends Atomic Radius Electronegativity Ionization energy Magnet Demonstration Effect of atomic structure on Periodic Trends Remember that all of the elements of the periodic table are made up of the simplest building blocks of matter called atoms The properties of the elements follow general patterns called trends. Effect of atomic structure on Periodic Trends When we observe the properties across a period or down a group, these trends can be explained by changes in atomic structure from one element to the next. Effect of atomic structure on Periodic Trends The periodic trends of atomic radius, electronegativity, and ionization energy can all be explained by changes in nuclear charge, and/ or the number of P.E.L. Effect of atomic structure on Periodic Trends [Think about magnets and attraction! Nuclear charge represents the strength of a magnet's attractive force and the number of principle energy levels represents the distance between the magnets.] ATOMIC RADIUS As we look at the elements across period the nuclear charge in each successive atom increases. However, the number of principle energy levels remains the same Therefore, with each successive element the second shell is pulled closer to the nucleus. This causes the atomic radius to decrease ATOMIC RADIUS: Period Trend CONCLUSION: Increased nuclear charge (# of protons) across the period causes the atomic radius to decrease ATOMIC RADIUS: Period Trend As we go down group 1 the number of principle energy levels increases. Therefore, each successive atom down a group increases in size. ( atomic radius) ATOMIC RADIUS: Group Trend CONCLUSION: Increased number of P.E.L. causes the atomic radius to increase down a group ATOMIC RADIUS: Group Trend The measure of the relative attraction of an atom for a foreign electron. ELECTRONEGATIVITY As we go across a period from left to right the nuclear charge increases. However, the number of principle energy levels remains the same. Therefore, elements to the right of the periodic table have an increased attraction for foreign electrons.( electronegativity) ELECTRONEGATIVITY: Period Trend CONCLUSION: Increased nuclear charge across a period causes an increase in electronegativity ELECTRONEGATIVITY: Period Trend As we go down a group the number of P.E.L. increases Therefore, there is an increased shielding effect and a weaker attraction by the nucleus for foreign electrons Therefore, each successive atom down a group decreases in electronegativity ELECTRONEGATIVITY: Group Trend CONCLUSION: Increased number of P.E.L. Causes an increased shielding effect, which decreased electronegativity ELECTRONEGATIVITY: Group Trend The amount of energy required to remove the outermost electron from an atom. IONIZATION ENERGY As we go across a period from left to right the nuclear charge increases. However, the number of principle energy levels remains the same. IONIZATION ENERGY: Period Trend Therefore, elements to the right of the periodic table hold onto their own valence electrons more strongly. This means it requires a larger amount of ionization energy exerted by a foreign atom to remove IONIZATION ENERGY: Period Trend CONCLUSION: An increase in nuclear charge across a period causes the ionization energy to increase IONIZATION ENERGY: Period Trend As we go down a group the number of P.E.L. increases Therefore, there is an increased shielding effect and a weaker attraction for its own valence electrons Therefore, it requires less ionization energy to remove a valence electron from these atoms as we go down a group IONIZATION ENERGY: Group Trend CONCLUSION: An increased shielding effect due to an increasing number of P.E.L. causes a decrease in ionization energy down a group IONIZATION ENERGY: GROUP Trend