1 / 92

# The Periodic Table of Elements

The Periodic Table of Elements. Periodic Table. Something “periodic” occurs at regular or generally predictable intervals Periodic law - physical and chemical properties of the elements are periodic functions of their atomic numbers

## The Periodic Table of Elements

E N D

### Presentation Transcript

1. The Periodic Table of Elements

2. Periodic Table • Something “periodic” occurs at regular or generally predictable intervals • Periodic law - physical and chemical properties of the elements are periodic functions of their atomic numbers • Periodic Table of Elements – a table of the elements, arranged by atomic number, that shows the patterns in their properties; based on the periodic law Can you think of anything that is periodic?

3. Element • A pure substance made up of one kind of atom that cannot be broken down into simpler substances by physical or chemical means • 90 occur naturally on earth • 25 were synthesized (made) by scientists • The Element Song http://www.privatehand.com/flash/elements.html

4. Dmitri Mendeleev • In the 1860’s he devised a periodic table where the elements were ordered by their atomic masses • He did this by grouping elements together according to their similarities • Draft of Mendeleev's Periodic Table Image taken from: http://jscms.jrn.columbia.edu/cns/2006-04-18/fido-luxuriantflowinghair/mendeleev/

5. Mendeleev’s Published Periodic Table of Elements Why do you think there are question marks here? Image taken from: http://www.chemsoc.org/networks/learnnet/periodictable/post16/develop/mendeleev.htm

6. Mendeleev’s Predictions • Although Mendeleev’s Periodic Table of Elements had missing elements or “gaps,” he was able to predict the characteristics of these missing elements because of Periodic Law. “Ekasilicon” Germanium Notice how Mendeleev’s predictions (orange column) were very accurate when compared to Germanium’s actual characteristics (green column)

7. Henry Moseley • In 1914, his work led to a revision of the periodic table by rearranging the elements by their atomic numbers • He concluded that the number of protons in an atom is its atomic number Image taken from: http://dewey.library.upenn.edu/sceti/smith/

8. 3 Classes of Elements Using this as a guide, color code your periodic table to show the classes.

9. Metals Location • Found on the left of the zigzag line/staircase on the periodic table (exception  Hydrogen) Chemical Properties • Have few electrons in their outer energy level, thus lose electrons easily Physical Properties • Ductile, good conductors, malleable, shiny, most are solid @ room temperature

10. - + + - - + + + + + - - - - + - - + + + + + - - + + - - - - Reference-Metals’ Chemical Properties Notice: only 1 electron in outer level 1s22s22p63s1 Notice: only 2 electrons in outer level 1s22s2

11. Metals’ Physical Properties • Good conductor- electrons (electricity) flow easily through the substance • Malleable- able to be hammered or pressed out of shape without breaking

12. Non-Metals Location • Found to right of the zigzag line/staircase Chemical Properties • Most have almost full outer energy levels, so tend to gain electrons; some completely full Physical Properties • Not ductile or malleable, not shiny, poor conductors, most are solid, but some are gas at room temperature

13. Metalloids Location • Border the zigzag line/staircase on the periodic table Chemical Properties • Most atoms have ½ (≈) complete set of electrons in outer level Physical Properties • have properties of both metals and non-metals • B, Si, Ge, As, Sb, Te, At

14. Using the Periodic Table • The boxes that make up the periodic table contain a significant amount of information Atomic Number (number of protons) Element Symbol (capital letter or a capital and lower case) Element Name Atomic Mass (weighted averages) • To understand this information, it is necessary to refer to the periodic table’s key(s)

15. Important Features of the Periodic Table • Period- each horizontal row of elements on the periodic table

16. Period (Series) Properties • Every element belongs to a period • Seven periods on a periodic table (numbered from the top down) • Period number = quantum number “n” = highest energy level of atoms where valence electrons are found • Carbon: 1s22s22p2 2nd period 131 • 40Zr [Kr] 5s24d25th period

17. Period (Series) Properties • Atomic numbers and atomic masses increase as you move from the left to the right in a period • Each element in a specific period has that respective number of levels • Ex • Period 1 elements = level 1 valence electrons • Period 2 = level 2 • Period 3 = level 3 • Etc…

18. Important Features of the Periodic Table • Group-column of elements on the periodic table

19. Group (Family) Properties • Eight main groups (numbered from left to right) • Not all elements belong to a group or family • Atomic numbers and atomic masses increase as you move from the top down in a group (family)

20. Group (Family) Properties • Elements in a group have similar properties and electron configurations • In an electron configuration, the NUMBER of valence electrons in the highest level is that element’s group, or family 108 • Ex 33As [Ar] 4s23d104p3 Group V- Nitrogen Family

21. Group #’s and Family Names-Reference GROUP FAMILY NAME EXAMPLE I Alkali Metals Na II Alkaline Earth Metals Ca III Aluminum Family Al IV Carbon Family C V Nitrogen Family N VI ChalcogenFamily O VII Halogen Family F VIII Noble or Inert Gas Family Ne

22. Group (Family) NamesLabel your periodic table Alkali Metals Boron Group Alkaline Earth Metals Noble Gases Transition Metalsnot a group Nitrogen Group Carbon Group ChalcogenGroup Halogens

23. Let’s Do It!!!! • Identify the element: • Group 2 Period 2 = • Group 7 Period 6 = • Group 6 Period 4 = • Group 1 Period 4 = • Group 4 Period 1 =

24. Let’s Do It!!!! • Identify the element: • Group 2 Period 2 = Be (Beryllium) • Group 7 Period 6 = At (Astatine) • Group 6 Period 4 = Se (Selenium) • Group 1 Period 4 = K • Group 4 Period 1 = Nada, nothing, zero, emptiness

25. 3 Classes of Elements

26. Transition Metals • Do not belong to a group and all are metals • Element where electrons are being placed into a “d” sublevel and “d” is last in electron configuration • Ex: 23V [Ar] 4s23d3 • Similar to Group II elements but some different properties because of the “d” electrons • They contain two dots in their dot structure

27. Rare Earth (Inner Transition) Metals • Do not belong to a group and all are metals • Element where electrons are being placed into a “f” sublevel and “f” is last in electron configuration Example: 92U [Rn] 7s25f4 • Similar to Group II elements but also some different properties because of the “f” electrons • All contain two dots in their dot structure

28. Summary • An element… • can be in a group OR • can be a transition element OR • can be a rare earth element • It may NOT belong to more than 1 of these 3 categories

29. ReviewPeriods and Groups video 10min • Number your paper from 1-5 and answer the following questions. Two will be cumulative review! • 1. Which of the following explains the difference between an atom and an ion? • Ions have different numbers of protons and neutrons • Ions have different numbers of protons and electrons • Ions have different numbers of neutrons and electrons • b. • c. • d.

30. Review • B • 2. What is the electron configuration of Calcium? • a. [Ar]4s2 • b. [He]2s1 • c. [Ne]3s2 • d. [K]4s2

31. Review • A • 3. What is true of elements in the same group? • They have similar electron configurations • They have similar properties • They are members of the same chemical family • All of the above

32. Review • D • 4. Which of the following describes the element chromium • In group I • In group II • A transition element • In group IV

33. Review • C • 5. How many valence electrons do transition metals have? • A. 1 • B. 2 • C. 3 • D. 4

34. Review • B….two dots in their Lewis dot structure

35. Periodic Trend #1: Metals vs. Non-metals • Metallic- able to lose electrons • DOWN GROUPS, elements become MORE metallic • Electrons are further from pull of positive protons so lost easier = conduct electricity • ACROSS PERIODS, elements become LESS metallic • More protons so more attraction • Gain more electrons and becoming more stable and less likely to lose electrons

36. Periodic Trend #2: Atom Size • 2 things affect the size of atoms: • Increasing the number of electrons increases the size (the more electrons, the bigger the atom) • Increasing the number of protons increases the attraction between the nucleus and electrons and decreases the size • These two statements contradict each other so which one is correct?

37. Periodic Trend #2: Atom Size • ACROSS PERIODS atoms DECREASE in size as electrons are being added to the same energy level(reason #2 is dominant over #1) ATOM Na Mg Al S P S Cl Ar SIZE (radius in Å) 1.54 1.36 1.18 1.11 1.06 1.02 .99 .98

38. Reference- Periodic Trend #2: Atom Size • DOWN GROUPS atoms INCREASE in size as the electrons go into a higher energy level (get farther away from the nucleus) (Reason #1 above is dominant over #2) ATOM SIZE (radius in Å) H .32 Li 1.23 Na 1.54 K 2.03 Rb 2.16 Cs 2.35

39. Ions • Ion- an atom with a charge due to different numbers of protons and electrons • Ex.) • Na atom 11 protons, 11 electrons = neutral • Na ion 11 protons, 10 electrons = +1 charge • With new electron structures, ions have different properties than the atoms from which they were formed • For an atom to “lose” an electron, a certain amount of energy needs to be absorbed

40. Periodic Trend #3Ionization Energy (I.E.) • Ionization energy- energy needed to remove an electron from an atom and form a positive ion • Generic formula X(atom) + ionization energyX+1(ion) + electron • Specific example Na + 119 Kcal/mole  Na+1 + electron • The ion is positive because it has 1 less electron than protons • Positive ions = “cations” • Smaller radius than original atoms

41. Reference- Periodic Trend #3Ionization Energy (I.E.) • ACROSS PERIODS ionization energy generally INCREASES • Increased attraction between the + nucleus and the electrons, hence a higher ionization energy ATOM: Na Mg Al Si P S Cl Ar I.E. (kcal/mole): 119 176 138 188 242 239 299 363

42. Reference-Periodic Trend #3Ionization Energy (I.E.) • DOWN GROUPS ionization energy generally DECREASES • Electrons in higher energy levels and farther away from the positive nucleus so less energy is required to remove them ATOM I.E. (kcal/mole) H 314 Li 124 Na 119 K 100 Rb 96 Cs 90 Cesium’s outer electron is much further away from the nucleus, therefore it is easier to remove

43. Periodic Trend #3Ionization Energy (I.E.) • The lower the ionization energy, the more chemically active the element will be • It will lose electrons and react or “bond” with other elementsmore readily • Metals have low ionization energies • Few electrons in their highest energy level • Electrons are weakly held and easily removed

44. Periodic Trend #3Ionization Energy (I.E.) • A metal will lose enough electrons until a stable electron structure, (usually a noble gas structure) is obtained: • Metals in Group I with s1 configurations will lose 1 electron and form +1 ions • Metals in Group II with s2 configurations will lose 2 electrons and form +2 ions • Metals in Group III with s2p1 configurations will lose 3 electrons and form +3 ions

45. Reference- Electron Configuration Comparison Atomconfig. of atomIonconfig of ion Na 1s22s22p63s1 Na+1 1s22s22p6 Mg 1s22s22p63s2 Mg+2 1s22s22p6 Al 1s22s22p63s23p1 Al+3 1s22s22p6 not stable stable

46. I.E. (cont.) • Most transition and rare earth elements vary in the number of electrons they lose so their charge will vary (can lose electrons from several sublevels) • Some transition elements, like silver, always lose the same number of electrons and always have the same charge • Non-metallic elements do NOT form positive ions as they would have to lose too many electrons to form a positive ion with an electron structure like a noble gas

47. Periodic Trend #4: Electron Affinity (E.A) • Electron affinity- energy released when an electron is gained by an atom General Formula X (atom) + electron ---> X-1 (ion) + energy Specific Formula Cl + electron ---> Cl-1 + 83.4 kcal/mole • This ion is negative because there is 1 more electron than proton • A negative ion = anion • Larger than the original atoms

More Related