The Periodic Table

1. The Periodic Table

3. Organizing the Elements • late 1790’s Antoine Lavoisier made a list of known elements • contained 23 elements • 1864 John Newlands looked further into organization • The Law of Octaves – repeating trends every 8 elements

4. Dmitri Mendeleev • Late 1800’s Russia • Grouped elements with similar properties into columns • 7 columns were formed • Noble Gases (8th Column) were later discovered • Was able to predict properties of missing elements • When Germanium was discovered, it fit his predictions

5. Question • Does mass always increase throughout the periodic table? • NOPE • Tellurium (52) • Iodine (53) • Nickel (28) • Argon (18) • Potassium (19)

6. Mendeleev’s Periodic Law • The properties of the elements are a periodic function of their atomic masses • periodic means repeating, like the moon cycle, every month it repeats • **atomic number was not known during Mendeleev’s time

7. Today’s Periodic Law • The properties of the elements are a periodic function of their atomic numbers • Using x-rays, Henry Moseley determined the number of protons per element • This is Atomic Number • Elements with similar e- configurations are in the same columns known as “groups” or “families” • Families  familiar characteristics • Families have the same number of v.e.’s

8. The Modern Periodic Table • Rows are periods, each row designates a different nrg level • Columns are groups or families and contain elements with similar properties • Notable rows and columns • Rows: • 4f – Lanthanides • 5f - Actinides • Columns: • 1 or IA – Alkali Metals • 2 or IIA – Alkaline Earth Metals • 17 or VIIA – Halogens • 18 or VIIIA – Noble gases

9. Representative Elements • “A” Groups • Filling the ‘s’ and ‘p’ sublevels • Contains both metals and non metals

10. Transition Metals • “B” Groups • Fills the ‘d’ sublevels • Made up of only metals

11. Inner Transition Metals • Fill the ‘f’ sublevels • Lanthanides • Actinides

12. Metals • Luster (shine) • Ductile (pulled into wires) • Malleable (hammerable and won’t shatter) • Good conductors of heat and electricity • Have 3 or less v.e.’sso they tend to lose them • Usually no more than 3 v.e.’s • Includes transition metals, actinides and lanthanides

13. Nonmetals • Brittle (most are gaseous) • Good insulators, not typically good conductors of heat or electricity • Have 5 or more v.e.’s, so they tend to gain (or share) e-’s

14. Metalloids • Elements with properties of both metals and nonmetals • Located on the diagonal between metals and nonmetals • There are 8 metalloids • Can lose or gain v.e.’s depending on their placement on the periodic table

15. Octet Rule • 8 e- in the outer nrg level make an atom not reactive or stable • Metals lose their e-’s to achieve octet • They become positive ( + ) = cations • Families 15 (VA), 16 (VIA), 17 (VIIA) gain e- to achieve octet • They become negative ( - ) = anions • All elements WANT 8 e-’s to become stable

16. Reactivity • The most active metals are in the lower left corner of the periodic table • The most active nonmetals are in the upper right corner of the periodic table Most active nonmetal Reactivity Decreases F Most active metal Reactivity Decreases Fr

17. The Periodic Table Periodic Trends

18. Atomic Radii • Increases as you go down a group • More e- = bigger radius • Atoms are gaining nrg levels • Decreases as you go across a period • e- are being added to the same nrg level • Nuclear charge – force of attraction between e- and nucleus • As you move across a period, more e- are being attracted to the nucleus

19. Atomic Radii • INCREASES as you go DOWN a group because of nrg levels • DECREASES as you go ACROSS a group because of nuclear charge • Noble gases radii are found to be larger because they don’t interact with other atoms of the same element as most others do.

20. Atomic Radii

21. Ions • Atoms can lose or gain e- to complete or empty an outer nrg level • Every atom wants an octet • Ion – an atom that has a + or – charge • Metals • Lose e- giving them a + charge • Decreases their radius • These are cations • Nonmetals • Gain e- giving them a – charge • Increases their radius • These are anions

22. Examples of Ions • Cations • H+, Li+, Na+, Mg2+, Ca2+ • Anions • F-, Cl-, O2-, S2-, N3-, P3- • **noble gases don’t have ions, they are stable and DO NOT IONIZE • *carbon doesn’t ionize a lot, it “shares” • When it does ionize, it gains 4 e- • Sizably increases its radius

24. Ionization Energy • Nrg needed to remove an e- from an atom • Unit = (kJ/mol) • ACROSS a period, it INCREASES • Due to increase in nuclear charge • DOWN a group, it DECREASES • Due to increased atomic radius and shielding effect • Metals = low I.E. • Nonmetals = high I.E. (especially noble gases)

26. 2nd Ionization Energy • Nrg needed to remove a second e- from an atom • Typically harder to remove a 2nd e- • **The higher the I.E., the more stable the atom. More stable, full/empty sublevels Be 1s 2s 2p 1s 2s 2p B Less stable, partial sublevels

27. Electronegativity • The power of an atom in a molecule to ATTRACT e- to itself • Ability to “hold on to e- more” • DECREASES from top to bottom of group • INCREASES from left to right in periods • F has the highest E.N. • High E.N.’s gain e- and form (-) ions • The more stable an atom, the less likely it will attract an e- • Would result in (-)E.N. • High E.N. = High electron affinity

28. Electronegativity • Like tug-o-war • Big guy (high E.N.) • Little guy (low E.N.) Decrease in E.N. F Decrease in E.N.

30. Facts • Most active metals (lower left) have the LOWEST E.N. • Fluorine has the highest E.N. • Noble Gases have NO E.N., because they don’t typically bond • No units for E.N. because it is a comparison • Deals with compounds and bonding