Electrons and the Periodic Table

1. Electrons and the Periodic Table Mrs. Freeman

2. History • HOW WAS MENDELEEV’S PERIODIC TABLE ARRANGED? • By their chemical properties •  HOW IS THE MODERN PERIODIC TABLE ARRANGED? • By increasing number of protons and atomic mass. • WHY DIDN’T MENDELEEV ARRANGE HIS TABLE THIS WAY? • Because at the time the number of protons was not known.

3. PERIODS: are a horizontal row of elements. • HOW MANY: 7 • VARIATION ACROSS A PERIOD: Changes from metals to metalloids to nonmetals

4. GROUPS AKA FAMILIES: the individual columns of elements. • HOW MANY? • 18 • SIMILARITIES BETWEEN ELEMENTS IN THE SAME GROUP? • They have the same number of valence electrons

5. THREE CLASSES OR CATEGORIES OF ELEMENTS ON THE PERIODIC TABLE

6. REACTIVITY PATTERN WITHIN A GROUP: increasing reactivity, decreasing melting and boiling point and density generally increases,

8. THE MOST REACTIVE METALS: • Francium, Cesium, and Rubidium (in order from most reactive to least reactive) • THE MOST REACTIVE NONMETALS: • Fluorine, Chlorine, and Bromine (in order from most reactive to least reactive)

9. Excited electron- • an electron in an energy level higher than its ground state (it has absorbed energy)

10. Ground state- • all the electrons have the lowest possible energy.

11. Energy Level- • The possible energies that electrons in an atom can have.

12. Sub-level • Electron orbital designated s, p, d or f. • These sublevels or orbitals have characteristic shapes which can be used to explain and predict the chemical bonds that atoms can form.

13. Orbital- • the region of space around the nucleus where an electron is likely to be found.

14. Energy level/energy shell- • the possible energies that electrons in an atom can have.

15. Three ways to show arrangements of electrons • Orbital Configuration Notation • Electron Configuration Notation • Electron Dot Notation

16. Electron configuration- • specific distribution of electrons in atomic orbitals of atoms or ions.

17. Valence shell- • the outside energy shell

18. Valence electrons- • an electron that is in the highest energy level of an atom.

19. Orbital Configuration Notation • each electron is assigned a space with an up spin or a down spin. • All up spins must be placed first. • Then place all down spins until all electrons are used.

20. Electron configuration notation: • is just the letters and numbers from the orbital configuration. • Example: Ar= 1s2 2s2 2p6 3s2 3p6

21. Electron dot notation: • the valence electrons represented by dots around the element symbol. • -fill in using the house memory trick

22. Hund’s Rule • every orbital in a subshell is singly occupied with one electron before any one orbital is doubly occupied, and all electrons in singly occupied orbitals have the same spin.

23. Aufbau Principle: • is used to determine the electron configuration of an atom, molecule or ion. The principle postulates a hypothetical process in which an atom is "built up" by progressively adding electrons.

24. Pauli’s Exclusion Principal • “no two electrons in the same atom can be in the same quantum state.” [1] This means that no two electrons can have the same set of quantum states of: 1) energy, 2) angular momentum magnitude, 3) angular momentum orientation, and 4) orientation of intrinsic spin.

25. Assessment • LIST THE PERIOD TO WHICH EACH OF THE FOLLOWING BELONGS: • STRONTIUM: • 5 • IRON: • 4 • RADON: • 6 • ANTIMONY: • 5 • HOW MANY ELEMENTS ARE IN PERIOD 4? • 18 • HOW MANY ELEMENTS ARE IN PERIOD 6? • 32

26. Assessment: • NAME THE ELEMENT IN GROUP 3 PERIOD 4 • Scandium. • HOW MANY VALENCE ELECTRONS ARE IN AN ATOM OF FLUORINE? • 7 • TO WHAT GROUP DOES CARBON BELONG • 14