CHEMISTRY 161 Chapter 1, p. 1- 39

1. CHEMISTRY 161 Chapter 1, p. 1- 39

2. Chemistry arabic: al-kimya greek: khymeia latin: chimica ‘FUSION’ ~ 3,500 BC

3. Solar System Chemistry

4. Chemistry in Space Amino Acids Sugars Star Formation Star Destruction ASTROBIOLOGY

5. PROPERTIES OF MATTER physical chemical density color odor reactivity EXPERIMENT I (determine w/ destruction of matter) CHEMICAL REACTION (determine w/o destruction of matter) state EXPERIMENT II

6. decomposition (water) EXPERIMENT III combination from two or more elements EXPERIMENT IV (exception: ozone)

7. ELEMENTS 1. cannot be decomposed by chemical means 2. different elements have different properties EXPERIMENT V 3. each element is assigned a unique chemical symbol (mostly one or two letters) BOOK • first letter is always capitalized • all remaining letter(s) are lower case

8. MATTER ATOMS John Dalton matter is composed of ‘building blocks’ MOLECULES ELEMENTS

9. Dalton’s postulates • Elements are composed of small particles called atoms; • atoms of an element are identical with same properties (mass) • 2. Compounds are composed of atoms of more than one element; • in a compound, the ratio of the number of atoms is an integer or fraction • LAW OF DEFINITE PROPORTIONS • 3. A chemical reaction involves separation and combination of atoms; • atoms are neither created nor destroyed an atom is the basic, undividable unit of any element

10. 1. Law of definite proportions 2. Law of conservation of mass in a chemical reaction no gain or loss of mass is observed unit of mass is g (gram) or kilogram (kg) one pound is 453.6 g each atom has a constant mass atomic mass – atomic weight

11. CHEMICAL MASS SCALE standard / calibration atomic mass unit (amu, u) one atom of carbon-12 12 u (exactly)

12. Structure of an Atom subatomic particles electrons protons neutrons

13. proton,p 1.67262 × 10-27kg +1.6022 × 10-19C +1 electron,e 9.10939 × 10-31kg -1.6022 × 10-19C -1 m(p) / m(e) ≈ 1836 the atom’s positive charge is located in a small, dense central core ‘nucleus’ protons are a constituent of the nucleus

14. + + + + + • mass of the nucleus constitutes most of the mass of the atom • 2. the nucleus is positively charged and contains protons • 3. the nucleus constitutes only about 1/1013 space of an atom • 4. electrons are as clouds around the nucleus

15. Neutron proton, p 1.67262 × 10-27kg +1.6022 × 10-19C +1 electron, e 9.10939 × 10-31kg -1.6022 × 10-19C -1 neutron, n 1.67493 × 10-27kg 0 0 m(n) / m(e) ≈ 1838 m(n) > m(p)

16. Structure of an Atom subatomic particles electrons (‘cloud’) neutrons (nucleus) protons (nucleus) neutrons are the ‘glue’ of the nucleus

17. Atomic Number and Mass Number mass number (number of protons plus neutrons) atomic number (number of protons) (number of electrons) in an atom, the number of electrons and protons are identical (charge neutrality)

18. 12 protons plus neutrons 6 neutrons 6 electrons 6 protons 13 protons plus neutrons 7 neutrons 6 electrons 6 protons elements with same number of electrons and protons but different number of neutrons ISOTOPES

21. Periodic Table of the Elements period http://www.webelements.com/ g r o u p ?

22. Periodic Table of the Elements metals nonmetals metalloids (semi metals) 8 main groups metals 10 transition metal groups lanthanides/actinides metals metals – shine, conduct electricity nonmetals – do not shine, do not conduct electricity metalloids – properties between metals and nonmetals

23. Summary 1. What is matter (atoms, molecules, substances, mixtures) 2. Dalton’s postulates 3. Chemical mass scale (amu, u) 4. Building blocks of atoms (electrons, protons, neutrons) 5. Periodic table of the elements