2 Chapter Big IdeaPeriodic trends in the properties of atoms allow us to predict physical and chemical properties!
3 Section 1: Development of the Modern Periodic Table
4 Essential Questions & Vocabulary How was the periodic table developed?What are the key features of the periodic table?VocabularyPeriod lawInner transition metalGroupLanthanide seriesPeriodActinide seriesRepresentative elementNonmetalTransition elementHalogenAlkali metalNoble gasAlkaline earth metalmetalloidTransitional metal
5 Section 1: Main IdeaThe periodic table evolved over time as scientists discovered more useful ways to compare and organize the elements.
6 LavoisierIn the 1700s, Lavoisier compiled a list of all the known elements of the time.
7 John Newlands (1864)The 1800s brought large amounts of information and scientists needed a way to organize knowledge about elements.John Newlands proposed an arrangement where elements were ordered by increasing atomic mass.Newlands noticed when the elements were arranged by increasing atomic mass, their properties repeated every eighth element (law of octaves).
8 Meyer and Mendeleev (1869)Meyer and Mendeleev both demonstrated a connection between atomic mass and elemental properties.Mendeleev is given more credit because he published his information first.Arranged elements in order of increasing atomic mass into columns with similar properties.Mendeleev was able to predict the existence and properties of undiscovered elements (blank spaces).
10 MoseleyA few elements were discovered and the atomic masses of the known elements were not accurately determined.Several elements in Mendeleev’s table not in the correct order.Moseley discovered that each element contain a unique number of protons in their nuclei – atomic numberMoseley rearranged the table by increasing atomic number, and resulted in a clear periodic pattern.
12 Periodic LawPeriodic repetition of chemical and physical properties of the elements when they are arranged by increasing atomic numberPeriodic comes from the Greek word “periodos”, meaning way around, circuit
14 The Modern Periodic Table The modern periodic table contains boxes that contain the element's name, symbol, atomic number, and atomic mass.
15 Modern Period Table Groups - Columns of elements Periods - Rows of elementsRepresentative Elements - Elements in groups 1,2, and 13–18 possess a wide variety of chemical and physical propertiesTransition Elements -Elements in groups 3–12Elements are classified as metals, nonmetals, and metalloids.
16 MetalsMetals are elements that are generally shiny when smooth and clean, solid at room temperature, and good conductors of heat and electricity.Alkali metals are all the elements in group 1 except hydrogen, and are very reactive.Alkaline earth metals are in group 2, and are also highly reactive.The transition elements are divided into transition metals and inner transition metals.The two sets of inner transition metals are called the lanthanide series and actinide series and are located at the bottom of the periodic table.
17 Nonmetals & Metalloids Nonmetals are elements that are generally gases or brittle, dull-looking solids, and poor conductors of heat and electricity.Halogens – elements in Group 17 which are highly reactiveNoble Gases – elements in Group 18gases at room temperature and are extremely unreactiveMetalloids, such as silicon and germanium, have physical and chemical properties of both metals and nonmetals.
20 Essential Questions & Vocabulary Why do elements in the same group have similar properties?Based on their electron configurations, what are the four blocks of the periodic table?VocabularyValence electron
21 Section 2: Main IdeaElements are organized into different blocks in the periodic table according to their electron configurations.
22 Electron Configuration Recall electrons in the highest principal energy level are called valence electrons.Only s & p orbital electrons count as valence electronsAll group 1 elements have one valence electron.
23 Valence Electrons - Practice How many valence electrons are in the following elements?Element# Valence ElectronsNaMgHHeClAl
24 Valence Electrons – Practice Solutions How many valence electrons are in the following elements?Element# Valence ElectronsNa1Mg2HHeCl7Al3
25 Lewis Dot StructuresDraw the Lewis dot structures for each of those elementsNaHeMgClHAl
26 Lewis Dot Structures of Representative Elements
27 The s-, p-, d-, and f-Block Elements The shape of the periodic table becomes clear if it is divided into blocks representing the atom’s energy sublevel being filled with valence electrons.
28 S- block Chemically reactive metals Group #1= alkali metals Slippery appearance and can be cut with a knife!For real?They all have one valence electronCombine readily with the halogens to form saltsGroup #2- Alkaline Earth MetalsHarder, denser and stronger than group #1 metalsHave 2 valence electrons
29 d- block - Transition Metals Lowest quantum # = 3Maximum # of electrons = 10There are exception to the electron configuration rulesSome metals may form several different ionsThey are all metals and good conductors of heat and electricity and have high luster.Properties vary greatly.Some metals are highly reactiveOther metals not so much- Au, Pt, Pd
30 p-block – Groups 13-18 Group 13- 3 valence electrons Group valence electrons etc. etc.Contains metals, non-metals and metalloids.Important group- #17- HalogensMost are gases- most reactive with metals
31 Main Group elements aka Representative Elements Elements found in the s block and p blockOnly elements that can be used in Lewis Dot Structures
32 Practice ProblemStrontium, which is used to produce red fireworks, has an electron configuration of [Kr]5s2. Without using the periodic table, determine the group, period, and block of strontium.
34 Essential Questions & Vocabulary What are the period and group trends of different properties?How are period and groups trends in atomic radii related to electron configuration?VocabularyEnergy level of an atomOctet ruleIonelectronegativityIonization energy
35 Section 3: Main IdeaTrends among elements in the periodic table include their sizes and their abilities to lose or attract electrons.
36 Atomic RadiusAtomic size is a periodic trend influenced by electron configuration.For metals, atomic radius is half the distance between adjacent nuclei in a crystal of the element.
37 Atomic RadiusFor elements that occur as molecules, the atomic radius is half the distance between nuclei of identical atoms that are chemically bonded together.
39 Shielding/ScreeningElectrons have an attraction or pull towards the nucleus of the atom (opposite charges attract)Electrons are also repelled away from the inner electrons (like charges repel)Shielding/ Screening: the attraction of valence (outer-shell) electrons is counterbalanced by the repulsion of the inner-shell electrons.The inner-shell electrons “screen” or “shield” the outer-shell electrons from full attraction
40 Effective Nuclear Charge Effective nuclear charge is the net positive charge experienced by valence electrons.
41 Atomic Radius Decreases From Left to Right Why?Increasing positive charge in nucleusValence electrons are not shielded from the increasing nuclear chargeIncreasing effective nuclear charge
42 Atomic Radius Increases Down a Group Why?Additional electron shells make the atom larger.Increases
43 Atomic Radii – Practice I Rank the following atoms in increasing atomic radius.CarbonBerylliumFluorineLithiumFluorine < Carbon < Beryllium < Lithium
44 IonsAn ion is an atom or bonded group of atoms with a positive or negative charge.Atoms become charged by either gaining or losing electrons.Cations: atoms lose electrons and become positively chargedAnions: atoms gain electrons and become negatively charged
45 Cations are smaller than the neutral atom The loss of a valence electron can leave an empty outer orbital, resulting in a smaller radius.Electrostatic repulsion decreases allowing the electrons to be pulled closer to the nucleus
46 Anions – Bigger than the neutral atom Why?The addition of an electron increases electrostatic repulsion.
47 Ionic RadiusThe ionic radii positive ions (cations) generally decrease from left to right.The ionic radii of negative ions (anions) generally decrease from left to right, beginning with group 15 or 16.Both positive and negative ions increase in size moving down a group.
49 Ionic Radii – Practice Mg2+ Na+ Ti3+ Arrange the following ions in order of increasing ionic radii:Na+, Ti3+, Mg2+Mg Na+ Ti3+
50 Atomic & Ionic Radii- Mixed Practice BCIf the figure represents the atoms helium, krypton, and radon, match the letter to the correct atom.If the figure represents a cation, an anion, and a neutral atom from the same period, match the letter to correct term.A – Radon B – Krypton C - HeliumA – Anion B – Atom C - Cation
51 Ionization EnergyIonization energy is defined as the energy required to remove an electron from a gaseous atom.First Ionization Energy - the energy required to remove the first electronIncreases from left to right across a period.Decreases from top to bottom in a group
52 Second Ionization Energy Second Ionization Energy – the energy required to remove a second electronEach successive ionization requires more energy, but it is not a steady increase.
53 Ionization EnergyWHY?Electrons are attracted to the nucleus. The closer they are to the nucleus, the stronger the attraction and the higher the energy needed in order to remove the electron.Opposite trend of Atomic RadiusSmaller radii – higher ionization energy
54 Ionization Energy - Practice Arrange the following elements in order of decreasing Ionization Energy.Al, Mg, Na, SiSi Al Mg Na
55 Interesting IE Pattern The ionization at which the large increase in energy occurs is related to the number of valence electrons.
56 Octet RuleOctet rule - states that atoms tend to gain, lose or share electrons in order to acquire a full set of eight valence electrons.The octet rule is useful for predicting what types of ions an element is likely to form.
57 Electronegativity Ability for an atom to attract electrons When it is chemically combined with another atom.Elements with high electronegativities (nonmetals) often gain electrons to form anions.Elements with low electronegativities (metals) often lose electrons to form cations.
58 Fluorine has the highest electronegativity Increases from left to rightDecreases from top to bottomOpposite trend of Atomic Radius. Smaller radii – higher electronegativity (closer electron can get to the nucleus)
59 Electronegativity Visual Which visual representation best describes electronegativity?The ability of a nucleus of one atom to attract an electron from another atom in a chemical bond.
60 Electronegativity - Practice Arrange the following in increasing order of electronegativity:Na, Li, KCa, Br, SeK Na LiCa Se Br