Understanding Chemical Foundations: Elements, Atoms, and Ions

1. Chapter 4 Chemical Foundations: Elements, Atoms & Ions

2. Elements • 114 known elements • 88 naturally occuring • Table 4.1 Page 84 • 98% earth’s mass – 9 elements

3. Fluorine F Oxygen O Carbon C One letter ALWAYS Capitalized Zinc Zn Chlorine Cl 2 letter symb. 1st letter always cap. 2nd letter never Capitalized Element Symbols

4. Original Greek or Latin Names

5. Original to New Names

6. Dalton’s Atomic Theory • 18th Century – items known • Most natural materials are mixtures of pure substances • Pure substances are either elements or combinations of elements called compounds • Law of constant composition • Water: 8g O to 1 g H

7. Dalton’s Atomic Theory • Elements are made of tiny particles called atoms • All atoms of an element are identical • Atoms of one element can combine with atoms of other elements to form compounds. A given compound always has the same relative numbers and types of atoms

8. Dalton’s Atomic Theory • Atoms are indivisible in chemical processes. Atoms are not created or destroyed in chemical reactions. A chemical reaction simply changes the way the atoms are grouped together.

9. Formulas of Compounds • Compound: Composed of 2 or more different elements • Chemical Formula: tells the types of atoms and how many of each atom is present

10. Rules for Writing Formulas • 1. Each atom is represented by it element symbol. • 2. The number of each type of atom is indicated by a subscript written to the right of the element symbol • 3. When only one atom of a given type is present, the subscript is not written.

11. Writing Formulas of Compounds • SO3 • N2O5 • C6H12O6

12. Writing Formulas of Compounds Page 90 Do Self-Check Exercise 4.1

13. Self-Check Ex. 4.1 • A. P4O10 • B. UF6 • C. AlCl3

14. The Structure of the Atom • Page 91: Plum pudding model • J.J. Thomson, late 1800s discovered electrons • William Thomson (AKA Lord Kelvin) proposed the pudding model • 1911 physicist Ernest Rutherford used alpha particles to study atoms • Alpha particles have a positive charge

15. The Structure of the Atom • Page 92 Rutherford’s thin foil experiment • Results were different than expected • Particles were deflected at large angles • He expected little if any deflection • Figure 4-6 • Results: meant a nuclear atom • Dense nucleus with a positive charge

16. The Structure of the Atom • Nucleus was surrounded by empty space occupied by electrons • 1919 Rutherford concluded the nucleus contained a particle called a proton • 1932 Rutherford and James Chadwick discovered the neutron • Neutron: slightly heavier than a proton but has no charge • Page 94: Table 4.4

17. ISOTOPES • Atoms with the same number of protons but a different number of neutrons • Atomic Number def. Number of protons • Mass Number def. Sum of the number of protons and neutrons • Page 95 Figure 4.10

18. ISOTOPES X = symbol of the element A = mass number (P + N) Z = Atomic Number (No. of P) Page 97 Do Self-Check Ex. 4.2

19. ISOTOPES # of protons = 38 # of electrons = 38 # of neutrons = 52 (90-38) Page 98 Do Self-Check Ex. 4.3

20. ISOTOPES # of protons = 80 # of electrons = 80 # of neutrons = 121 (201-80) Homework: Pages 117-118 39-42

21. The Periodic Table • Periodic Table: lists all the known elements and various characteristics of the elements in an organized style • Page 99 Figure 4.11 • Group or Family: vertical column of elements

22. The Periodic Table • Group 1 alkali metals • Group 2 alkali earth metals • Group 7 halogens • Group 8 noble gases • Transition metals

23. The Periodic Table Physical properties of metals • Efficient conductor of heat and electricity B. Malleable (hammered into thin sheets) C. Ductile (drawn into wires) D. Lustrous (shiny) appearance

24. The Periodic Table Location of: Metals Nonmetals – Properties Metalloids (semimetals) – Properties Page 101 Figure 4.12