Unit 3 Atoms and the Periodic Table

1. Unit 3 Atoms and the Periodic Table

2. Periodic Table • Demetri Mendeleev is credited for creating the first version of the modern periodic table • The periodic table is a chart showing all the elements arranged in columns in such a way that all the elements in a given column exhibit similar chemical properties • The periodic table shows all of the known elements in order of increasing atomic number.

3. Periodic Table • Periodic table is broken up into 3 main groups: Metals, nonmetals, and metalloids. • Metals are on the left (except H) • Nonmetals are on the right • Metalloids are along the stair step (except for Al) • The stair step starts under boron

4. Periodic Table • Physical Properties of Metals • Over 80% of all elements are metals • Efficient conduction of heat and electricity • Malleability (can be hammered to thin sheets) • Ductility (can be pulled into wires) • A lustrous (shiny) appearance • Tend to lose electrons in chemical reactions • Left side of the periodic table • Very high melting and boiling points • All metals are solid at room temperature • Except mercury, which is a liquid • Different types of metals • Alkali, alkaline earth, transition, and inner transition.

5. Periodic Table • Physical Properties of Nonmetals • Right side of the periodic table • Do not conduct electricity or heat • Nonmetals are solids, liquids, and gases • Bromine is the only liquid nonmetal at room temperature • They are not ductile or malleable. • They are brittle • No Luster • Lower melting and boiling points • Tend to gain electrons in chemical reactions

6. Periodic Table • Physical Properties of Metalloids • Border Stair Step • Properties of both metals and nonmetals • Various melting and boiling points (can be high or low) • Semi conductors of electricity • Some have luster • Generally more brittle than metals but less brittle than nonmetals

7. Periodic Families Lanthanides Actinides 1 or 1A- Alkali Metals 13 or 3A- Boron Group 16 or 6A- Chalogens or Oxygen group 2 or 2A- Alkaline Earth Metals 14 or 4A- Carbon Group 17 or 7A- Halogens 3-12 Transition Metals 15 or 5A- Nitrogen Group 18 or 8A- Noble Gases

8. Vertically into Groups or Families- Horizontally Into Periods Elements are arranged:

9. Each atom within the same family has the same number of electrons in it’s outermost shell. The electrons in the outermost shell are called valance electrons. Valance electrons are the part of the atom that are involved in chemical reactions. Why do elements in the same family have similar properties?

10. The group 2 atoms all have 2 electrons in their outer shells Be (Beryllium) Atom Mg (Magnesium) Atom

11. The number of valence electrons in an atom effects the way an atom bonds. • The way an atom bonds determines many chemical properties of the element. • This is why elements within a group usually have similar properties.

12. Valance Electrons By Family 1 2 2 3 4 5 6 7 8

13. If you looked at an atom from each element in a period you would see…Each row has the same number of energy levels

14. The period 4 atoms each have 4 electroncontaining shells or energy levels 4th Shell K (Potassium) Atom Kr (Krypton) Atom Fe (Iron) Atom

15. Alkali Metals Soft, silvery colored metals Very reactive because they have only 1 valence electrons. Most reactive metals

16. Alkali Metals reacting with water: • https://www.youtube.com/watch?v=eD9BiYvsT4k

17. Alkaline Earth Metals Silvery-White Metals Fairly reactive Many are found in rocks in the earth’s crust

18. Transition Metals Less reactive than other metals Most are good Conductors of electricity Malleable (easily bent/hammered into wires or sheets)

19. How many things can you think of that have Transition Metals in them?

21. Metalloids lie on either side of these “stairsteps” They share properties with both metals and non-metals Si (Silicon) and Ge (Germanium) are very important “semi-conductors”

22. What are semiconductors used in?

23. Halogens Most are Poisonous Most reactive nonmetals

24. Chlorine Gas was used as a chemical weapon during World War I. It was used by the Nazis in World War II.

25. Noble Gases Inert (unreactive) because they have filled their electron shells. Gases at room temperature

26. Jellyfish lamps made with noble gases artist- Eric Ehlenberger

27. Lanthanides and Actinides together make up the inner transition metals • Have properties of metals • Very heavy metals • Some are radioactive Lanthanide Series Actinide Series

28. Dalton’s Atomic Theory • All elements are composed of atoms. • All atoms of a given element are identical. (not 100% true) • Atoms of different elements are different. • Compounds consist of the atoms of different elements. • Atoms are not created or destroyed in a chemical reaction.

29. Parts of an Atom Nucleus • Nucleus– The center of the atom, contains protons and neutrons. • The nucleus contains majority of the atom’s mass • Electron cloud- the outer part of the atom where electrons are found. • The electron cloud is made up of energy levels • Energy levels are made up of sublevels • Sublevels are made up of orbitals • The electron cloud contains majority of the atom’s volume Energy level

30. Part of the Atom • Protons– located in the nucleus. Has a positive charge. Elements are identified by the number of protons it contains. • Neutrons– located in the nucleus. Has a neutral charge. • Electrons– located in the electron cloud. Have a negative charge.

31. Atomic Structure * Amu stands for atomic mass unit

32. The Periodic Table of Elements

33. Atomic Numbers • The whole number is the atomic number- This identifies the element • # of protons = atomic # • # of electrons = # of protons – charge • Charge= # of protons – # of electrons • # of neutrons = Mass number – # of protons • Mass number = # of protons + # of neutrons • Mass # is mass of individual atom • The number with the decimal is the average atomic mass

34. Practice • How many protons are in Zinc? • What is the atomic number of Calcium? • What is the average atomic mass of Oxygen? • How many neutrons are in Lithium? • How many electrons are in a neutral Carbon atom? • Why do the number of protons equal the number of electrons in a neutral atom?

35. Atoms • Period # indicates the number of energy levels • The first energy level (or ring around the nucleus) can only hold 2 electrons • Once the first ring is “full”, the next set of electrons will begin to fill in to a new energy level. • With the exception of the first orbital, all outer energy levels only want to have 8 electrons. • This is called the Octet rule • Atoms will gain or lose valance electrons to fill their octet • Once the octet has been reached, a new energy level will be made. • Exception: smaller atoms like H, He, Li, Be will be stable with 2 electrons (called the Duet Rule) • There are other exceptions that we will not worry about

36. Anatomy of the Atom • TheBohr Model of the atom suggests that the nucleus is in the center of the atom and the electrons are located outside the nucleus circling around it in energy levels.

37. What will the Bohr model Hydrogen look like? There is only one energy level with 1 electron and there is 1 proton In the middle of the atom .

38. Another example • Structure of Lithium • Atomic Number • 3 protons • 3 electrons • Lets assume that there is 4 neutrons. • Lets draw the Bohr model.

39. What does Lithium look like?

40. Try some examples • Oxygen

42. Argon • Assume it has a whole number of neutrons

44. Lewis Structures • Lewis Structures are another way to model the atom • A Lewis structure is a representation of an element and its valance electrons • For example: Carbon has 4 valance electrons • Lewis structure for Carbon:

45. Drawing Lewis Structures • Example Oxygen • Step 1: Write the elemental symbol for the element- O • Step 2: Determine the number of valance electrons- 6 • Step 3: Place one electron on each side of the atom, then place remaining electrons around the atom

46. Draw the Lewis Structures • Gold • Silicon • Bromine

47. Ions • When atoms gain or lose electrons to form an octect, the atom becomes charged • Why? The number of protons (+) and electrons (-) are no longer equal • Ion- an atom or molecule with a net electric charge due to the loss or gain of one or more electrons. • Positive ions are called cations • Negative ions are called anions • Metals tend to lose electrons to become cations • Nonmetals tend to gain electrons to become anions

48. Charges By Family Various positive charges Silver is always +1 Zinc and Cadmium are always +2 Various Charges +1 +2 -3 -2 -1 0 +3

49. Practice • If a sodium atom loses an electron, what will its charge be? • How many electrons will aluminum need to gain or loses in order to reach its octet? • How many electrons will oxygen need to gain or loses in order to reach its octet? • How many electrons are in the following? • Cl-1 • Ca2+

50. Lewis Structure of Ions • When drawing a Lewis structure of an ion, put the charge as a superscript in the upper right hand corner of the symbol • If the ion is positive, it has lost electrons, so remove electrons • It should leave you with an empty valance shell • If the ion is negative, it has gained electrons, so add electrons • It should leave you with a full octet • Example: draw the Lewis structure for the following ions • Calcium ion • Nitrogen ion • Aluminum ion