1. Engineering Chemistry 14/15 Fall semester Instructor: Rama Oktavian Email: rama.oktavian86@gmail.com Office Hr.: M.13-15, Tu. 13-15, W. 13-15, Th. 13-15, F. 09-11

2. Outlines 1. Mass conservation theory of matter 2. Atom: Theory 3. Compounds: Bonding 4. Mixtures

3. Review Unit conversion Physical and chemical properties

4. Review Significant figure in measurement

5. Mass conservation Fundamental law the total mass of substances does not change during a chemical reac­tion - Antoine Lavoisier (1 743-1 794) The number of substances may change, but the total amount of matter remains constant. matter cannot be created or destroyed.

6. Mass conservation Fundamental law - the law of definite (or constant) composition no matter what its source, a particular compound is composed of the same elements in the same parts (fractions) by mass Denoted as mass fraction or mass percent, mass %

7. Mass conservation Fundamental law - the law of definite (or constant) composition

8. Mass conservation Example

9. Mass conservation Multiple proportion if elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole num­bers.

10. Mass conservation Conceptual question

11. Atom theory Atomic Number, Mass Number, and Atomic Symbol Isotopes of an element are atoms that have different numbers of neutrons and therefore different mass numbers. Example: 12C, 13C, 14C

12. Compound: Bonding Elements combine in two general ways: 1.Transferring electrons from the atoms of one element to those of another to form ionic compounds 2.Sharing electrons between atoms of different elements to form covalent compounds

13. Compound: Bonding Ionic bonding

14. Compound: Bonding Covalent bonding Covalent compounds form when elements share electrons, which usually occurs between nonmetals Atoms of different elements share electrons to form the molecules of a covalent compound

15. Compound: Bonding Covalent bonding mechanism

16. Mixtures Classification of mixtures matter usually occurs as mixtures, such as air, seawater, soil, and organisms A heterogeneous mixture has one or more visible boundaries between the components Example: rocks A homoge­neous mixture has no visible boundaries because the components are mixed as individual atoms, ions, and molecules. Example: sugar dissolves in water

17. Mixtures Summary of matter