WoC Ch 3.8 Intro to the Periodic Table

1. WoC Ch 3.8 Intro to the Periodic Table Objective: Learn about various features of the periodic table Objective: Learn some of the properties of metals, non-metals, and metalloids

2. Periodic Table6C12.001Elements are listed • A chart that shows all of the known elements and gives a lot of information about each Atomic number Chemical symbol Mass Number • On the periodic table in order of increasing atomic number

3. More arrangement…1869 Russian scientistArranged by familiesChlorine and Fluorine behave similarly, as do potassium and sodiumWhat are the atomic numbers of Cl, F, K, and Na • Elements are also arranged in specific horizontal rows and vertical columns • Dmitri Mendeleev-Father of the Periodic Table • Mendeleev arranged the P.T. this way because of similarities in the chemical properties of various “families” of elements • The periodic table refers to the fact that as we increase the numbers, every so often an element occurs with properties similar to those of a lower number element • ____,____,____,____

4. Vertical columns are calledGroups are often referred to bySee Discovery School Circle Periodic TableMany groups have special namesGroup 1Group 2Group 7 (17)Group 8 (18)Large collection spanning many vertical columns • Families and/or Groups • The number over the column • For simplicity we delete all of the “A”s Alkali Metals Alkaline Earth Metals Halogens Noble gases Transition metals

5. Relatively small number of elements in the upper right hand corner of the periodic tableMany non-metals areOne is liquidSeveral non-metals areElements that lie close to the stair-step line • Non-Metals • Lack characteristics of metals • Have more variation in their properties Gaseous Bromine (Br) Solids Metalloids or Semi-metals Show a mixture of metallic and non-metallic properties

6. Most elements are metals • Physical properties • Efficient conduction of heat and electricity • Malleable • Ductile • A lustrous (shiny) appearance • Most metals are solid at room temperature

7. Knowledge of the Periodic Table… Is extremely useful in the study of chemistry! • Describe most of the elements on the periodic table. • List one element that is liquid at room temperature. • What information is usually found in each individual square of the periodic table?

8. WoC Chapter 3.9 Natural States of the Elements Objective 1: Learn the natures of the common elements

9. Define CompoundNoble Metals(Relatively unreactive)Group 8Air sample yieldsDiatomic molecules Atoms from different elements are chemically bonded Gold, Silver, Platinum Noble Gases: He, Ne, Kr, Xe, Rn Pure element, existing as single atom: Argon Diatomic molecules: N2 & O2 Molecules made of 2 atoms

10. 7 Diatomic Molecules to knowMost elements in Group 7 and Group 8 2 are liquids in elemental formNon-metallic structures are more variedEx: H,N,O,F,Cl,Br,I are all diatomic molecules Are gases at room temperature (25°C) Hg (Mercury) and Br (Bromine) Allotropes-elements whose atoms make different forms Carbon: Diamond, graphite, buckminster fullerene

11. WoC Chapter 3.10Ions • Objective 1: Describe the formation of ions form their parent atoms and learn to name them. • Objective 2: Predict which ion a given element forms by using the periodic table.

12. Q: If an atom has a certain number of protons in the nucleus and an equal number of electrons in its valence shell, what can be said about the overall charge of the atom? A: The fact that the number of protons and electrons is equal results in an exact balance of positive and negative charges. Thus, an atom is neutral. It has zero net charge!!

13. IonTake a neutral atomAdd an electronRemove an electronEx: Sodium atom Z=11One electron is lost11+ + 10- = 1+CationAnionCationsMg Mg2+ + 2e-Al Al3+ + 3e- • A charged entity negative ion forms positive ion forms 11 protons 11 electrons 11+ 10- Na Na+ + e- Positive ion Negative ion Magnesium forms a 2+ cation Aluminum forms a 3+ cation

14. Cations are named Sodium NaMagnesium MgAnionAnionsChlorine Cl + e-Fluorine F + e-Bromine Br + e-Iodine I + e- • Using the name of the parent atom • Na+ Sodium ion • Mg2+ Magnesium • Negatively charged ion • Gain electrons • Cl- • F- • Br- • I-

15. Anions are named Chlorine becomesSome atoms gain 2 electronsex: Oxygen O + 2e-Sulfur S + 2e-Ions are always formed • By taking the root name of the atom and changing the ending to –ide • Chloride • O2- oxide ion • S2- sulfide ion • By removing electrons from an atom or adding electrons to an atom

16. IONS ARE NEVER FORMED BYIsolated atoms do not form ions on their ownWhen metals and nonmetals reactMetals and nonmetals tend to form compounds that • CHANGING THE # OF PROTONS!!! • Most ions are formed when metallic elements combine with nonmetallic elements • Metal atoms tend to lose one or more electrons, which are in turn gained by atoms of the nonmetal • Contain metal cations and nonmetal anions

17. WoC Chapter 3.11Compounds That Contain Ions • Objective 1: To describe how ions combine to form neutral compounds

18. Chemists have reason to believe that many chemical compounds contain ionsConsider common table salt (NaCl)As a solidWhen meltedPure waterbut when salt is dissolved in water • 800°C to melt • 1500 °C to boil • Will not conduct electricity • Is a very good conductor • Will not conduct electricity • The solution readily conducts electricity

19. These properties are best explained by picturing NaCl as containing Na+ ions and Cl- ions

20. Sodium chloride breaking apart (ionizing) in solution

21. Electric current can travel along a metal wire becauseThe moving electronsIn ionic substancesThus, substances that contain ions can conduct an Electrons are free to move through the wire Carry the current the ions carry the current Electric current only if the ions can move.

22. Electron movement in wire and ionic substances

23. The body uses ions in the Sodium/Potassium Pump in Cell membranes

24. In solid NaCl, ions are tightly held and cannot move. However,As a result, an electric current can travel through The same reasoning applies to NaCl dissolved in water • When solid is melted and becomes liquid, the structure is disrupted and the ions can move • The melted salt! • When the solids dissolve, the ions are dispersed in the water and can move!

25. We recognize substances that contain ionsMany substances contain ionsThese substances are called …A chemical compound must have • By their characteristic properties. • Very high melting point • Conduct electricity when melted or dissolved in water Whenever a compound forms between a metal and a nonmetal, it can be expected to contain ions. IONIC COMPOUNDS A net charge of zero!

26. If a compound contains ions • There must be both positive (cations) ions and negative (anions) ions. • The number of cations and anions must be such that the net charge is zero

27. Na+ + Cl- NaCl

28. Na+ + Cl- NaCl

29. Mg2+ + O2- MgO

30. More Ionic Bonding

31. Remember this Periodic Table trend?

32. When bonding… • You must have ions: anions and cations • When they combine, the resulting compound will have no net charge • This means that the number of atoms of each element must be accounted for so that the number of anions and cations in the compound is the same • You notate the number of atoms needed by using subscripts. Ex: Na2O, MgCl2