Atoms and the Periodic Table

1. Atoms and the Periodic Table Chapter 4

2. Families of Elements Section 3

3. Organization of the Periodic Table • The Periodic table groups similar elements together to make it easier to predict the properties of an element based on its location. • How is the Periodic Table organized? • Based on the number of protons, or atomic number, an element has in the nucleus of an atom.

4. Organization of the Periodic Table • Periodic Law • States that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements. • Periods • Horizontal rows of elements in the Periodic Table. • Groups • Vertical columns of elements in the Periodic Table.

5. How Are Elements Classified? Figure 22 B, Page 120

6. How Are Elements Classified? • Metals • An element that is lustrous, ductile, malleable and conducts heat and electricity well. Lose electrons to form cations. • Nonmetals • An element that conducts heat and electricity poorly. • Can be solids, liquids or gases. Solids are typically dull and brittle. Gain electrons to form anions. • Metalloids • An element or compound that conducts electric current better than an insulator but not as well as a conduct does.

7. Metals • Alkali metals • The elements in Group 1 on the Periodic Table. • Soft and shiny • React violently with water. http://www.youtube.com/watch?v=uixxJtJPVXk • Why do these metals react so violently?

8. Metals • Alkaline-earth • Group 2 elements on the Periodic Table. • Still react with water, but not violently. • Calcium compounds • Used for construction • “skeletons” of animals • Strength for teeth and bones.

9. Metals • Transition Metals • Elements from groups 3-12 of the Periodic Table. • Actinides and Lanthanides • Located below the Periodic Table • Lanthanides are also considered Rare Earth Metals, along with scandium and yttrium. • Essential to medical diagnosis equipment and almost all military systems. Critical components for modern electronic technologies.

10. Metals • All metals conduct heat and electricity. • They are all ductile, malleable and lustrous. • Most metals can be stretched and shaped into flat sheets or pulled into wires. • Radioactive • The nuclei of the atoms are continually decaying to produce different elements. • Elements with atomic number greater than 92 are man-made, and from 84 and greater are radioactive.

11. Nonmetals • Carbon • Graphite, pencil lead • Diamonds • Sugar, or glucose • Chlorophyll • Fullerenes • Oxygen and Nitrogen are the most plentiful gases in the air we breathe.

12. Nonmetals • Halogens • Group 17 on the Periodic Table. • Chlorine protects you from harmful bacteria. • In gas form, it is a poisonous yellowish green gas that consists of two chlorine atoms bonded together, Cl2. • Fluorine is a poisonous yellowish gas. • Bromine is a dark red liquid. • Iodine is a dark purple solid.

13. Nonmetals • Diatomic Gases • Made up of two atoms • There are 7 diatomic atoms: • Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, and Iodine. • H2, N2, O2, F2, Cl2, Br2, and I2

14. How Are Elements Classified? Figure 22 B, Page 120

15. Nonmetals • Noble Gases • Group 18 on the Periodic Table. • The gases are inert. • Found as single atoms in nature, not molecules.

16. Nonmetals • Metalloids • An element or compound that conducts electric current better than an insulator but not as well as a conductor. • Nonmetals that have some properties of metals. • Found along the stair-step line. • 7 metalloids: • Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, and Polonium. • B, Si, Ge, As, Sb, Te, Po Figure 31, Page 127

17. Nonmetals - Metalloids • Boron • Extremely hard, added to steel to increase hardness and strength at high temperatures. • Often used for heat-resistant glass. • Arsenic • Shiny solid that tarnishes when exposed to air. • Antimony • Bluish white brittle solid that shines like a metal. • Found in fire retardants. • Tellurium • Is a silvery white solid whose ability to conduct increases slightly with exposure to light.

18. Nonmetals - Metalloids • Silicon • Accounts for 28% of the mass of the Earth’s crust. • Sand, silicon dioxide: SiO2. • Computer chips, transistors, LED display screens, and solar cells. • Impurities increase ability to conduct electricity.

19. A Guided Tour of the Periodic Table Section 2

20. Some Atoms Form Ions • Ionization • An atom gains or loses valence electrons in order to have a full outermost ‘s’ and/or ‘p’ orbital. • When atoms gain or lose electrons, the atom is no longer neutral. • Ion • An atom or group of atoms that has lost or gained one or more electrons, has a negative or positive charge.

21. Some Atoms Form Ions • Cation • Positively charged ion that has lost an electron. • All metals are cations. • Anion • Negatively charged ion that has gained an electron. • All nonmetals are anions.

22. How Do the Structures of Atoms Differ? • Atomic number, Z • The number of protons in the nucleus of an atom. • The atomic number never changes for a given element. • Mass number, A • the sum of the numbers of protons and neutrons in the nucleus of an atom.

23. How Do the Structures of Atoms Differ? • Isotope • An atom that has the same number of protons as other atoms of the same element do but has a different number of neutrons. • Hyphen notation • The name of the element, hyphen, and then the mass number of the isotope.

24. How Do the Structures of Atoms Differ? • Isotopes of Hydrogen • Protium-1 • Deuterium-2 • Tritium-3

25. How Do the Structures of Atoms Differ? • Finding the number of Neutrons: • Mass Number – Atomic Number = Number of Neutrons • Example: Oxygen-18

26. How Do the Structures of Atoms Differ? • Average Atomic Mass • The weighted average of the masses of all naturally occurring isotopes of an element. • Using average atomic mass, round to nearest whole number to find the mass number. • Atomic Mass unit (amu) • A unit of mass that describes the mass of an atom.

27. Atomic Structure Section 1

28. What are Atoms? • What are atoms? • Tiny particles that determine the properties of all matter. • Translates to “unable to be divided”. • The smallest part of an element that maintains that element’s properties. • Who was Democritus? • A Greek philosopher who believed the movements of atoms caused the changes in matter that he saw.

29. What are Atoms? • John Dalton • An English school teacher who developed his own atomic theory that formed the foundation for the modern atomic theory. • Dalton’s Atomic Theory: • Atoms of different elements can join to form compounds. • All atoms of a given element are exactly alike. • Atoms cannot be divided. • Are the last two assumptions true?

30. What’s in an Atom? • Atoms can actually be divided into smaller particles. What are the particles? • Proton- subatomic particle that has a positive charge, found in the nucleus. • Neutron- subatomic particle that has no charge, found in the nucleus. • Electron- subatomic particle that has a negative charge, found outside the nucleus in the electron cloud. • Electrons are about 2000 times smaller than a proton and a neutron. Table 1, Page 106

31. What’s in an Atom? • Nucleus- center of an atom where the protons and neutrons reside. • Electron cloud- the area where the electrons orbit around the nucleus of an atom. • Do atoms have a charge?

32. Models of the Atom • Models have been adapted as new information has been discovered. • Niels Bohr suggested that: • Electrons move in set paths around the nucleus. • Each electron has a certain energy, and the path defines the electrons energy level.

33. Models of the Atom • How can electrons move from one energy level to another? • Absorption- • the take in of energy. • Emission- • the release of energy. Figure 5, Page 107

34. Models of the Atom • Bohr’s model no longer explains electrons behavior, but helps in understanding energy levels. • Do not orbit in definite paths. • In the current model of the atom, electrons move like waves.

35. Models of the Atom • Heisenberg Uncertainty Principle • Cannot predict where an electron is located and the speed at the same time. • We can calculate the chance of finding an electron at a certain location.

36. Models of the Atom • Each energy level can have a certain number of electrons. • Can determine energy level by a simple equation: 2n2. • In each energy level, there are certain “orbitals” that the electrons can be found in. Figure 7, Page 108

37. Models of the Atom • Valence electrons- • Electron(s) that are found in the outermost shell of an atom. • Valence electrons determine the atom’s chemical properties and its ability to form bonds. • How many valence electrons can an atom have? • How can we determine valence electrons in an atom?

38. Models of the Atom • Orbitals- • The regions in an atom where electrons are going to be found 90% of the time. • There are four different orbitals. • S, p, d, and f • Each orbital can be occupied by a total of two electrons.

39. Models of the Atom • The ‘s’ orbital • The lowest energy occupied orbital. • There is only one orbital for ‘s’. • Spherically shaped. Figure 8, Page 109

40. Models of the Atom • The ‘p’ orbital • There are three orbitals for ‘p’. • The ‘p’ orbital can have a total of 6 electrons. • This orbital has a dumbbell shape. Figure 9, Page 109

41. Models of the Atom • The ‘d’ and ‘f’ orbitals are more complex than ‘s’ and ‘p’. • The ‘d’ orbital has 5 orbitals and can hold a total of10 electrons. • The ‘f’ orbital has 7 orbitals and can hold a total of 14 electrons.

42. Location of the orbitals

43. Models of the Atom • Electron configurations- • The arrangement of electrons in the orbitals. • ‘d’ orbitals have a lower coefficient than ‘s’ and ‘p’ when written. • How do we write them?

44. Models of the Atom • Noble Gas Configuration • The short hand way of writing electron configurations. • Take the noble gas that comes before the element that the configuration is being written for. • Put the noble gas in brackets [ ]. • Write the rest of the configuration like normal.