1. Chemistry—An Introduction Chapter 2 Pages 25-33

2. Matter Occupies space and has mass Mass is NOT the same as weight States of matter Solid Liquid Gaseous

3. Energy Can only be measured by effect on matter Defined as: The capacity to do work Two types Kinetic energy Potential energy

4. Forms of Energy Chemical energy Electrical energy Mechanical energy Electromagnetic energy All forms are easily convertible

5. Elements and Atoms All matter composed of elements Cannot be broken down Ex: Oxygen, Carbon, Gold, Silver, Copper, Iron Elements composed of atoms Unique in each element Atomic symbol Abbrev. for element O = Oxygen, C = Carbon

6. Atomic Structure Atoms contain smaller structures Nucleus Most dense and most of mass of atom (1amu) Neutrons (n 0 ) Protons (p + ) Electrons (e - ) Tiny, 1/2000 mass of protons and neutrons Equal number of protons and electrons

8. Identifying Elements

9. Atomic Number = to number of protons in a nucleus Written as subscript to Left of atomic symbol Ex: ( 1 H); ( 2 He)

10. Mass Number = to sum of masses of protons + neutrons Ex: H mass number = 1(p + ) + 0 (n 0 ) = 1 He mass number = 2 (p + ) + 2 (n 0 ) = 4 Written as superscript to Left of atomic symbol Now know total numbers of all subatomic particles Structural variations Called isotopes Differ in number of neutrons

11. Atomic Weight Avg of mass numbers of all isotopes of an element Also takes into account relative abundance Ex: H atomic wt. = 1.008

12. Molecules and Compounds Molecule Two or more atoms held together by a chemical bond Compound Two or more different atoms held together by a chemical bond Chemically pure

13. Mixtures Composed of two or more substances that are physically mixed Three types: Solutions Colloids Suspensions

14. Solutions Homogeneous mixtures Solvent Substances present in greater amt Solute Present in smaller amts

15. Concentration of Solutions Described in terms of % of the solute in solution Can also describe in terms of molarity (moles per liter) (M) Mole = to molecular weight Avogadro’s number = 6.02 x 10 23 Makes sure that the substance always contains exactly same number of solute particles

16. Colloids Heterogeneous mixtures Appear milky Ex: Jello-O, cytosol

17. Suspensions Heterogeneous mixtures Contain lg solutes that settle out Ex: Sand and water Ex: Blood

18. Mixtures vs. Compounds No chemical bonding occurs between components of a mixture Mixtures can be separated by physical means; compounds cannot Mixtures can be hetero- or homogeneous; compounds are only homogenous