1. Unit 4: General Chemistry
Matter and its properties

2. OBJ: Distinguish among atoms, elements, compounds, and molecules
Matter
OBJ: Distinguish among atoms, elements, compounds, and molecules

3. The Atom
Basic unit of matter
Made up of protons, neutrons, electrons

4. Atom: Subatomic particles
Nucleus: protons (+) and neutrons (0) bind together at the center of the atom
Electrons: negatively charged particle; constantly moving around the nucleus

5. Elements
Pure substance
Consists of one type of atom

6. Atomic Number = Proton #, electron #
Atomic Mass = protons + neutrons

7. Main Elements in Living Things
Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
We also need: phosphorus and sulfer

8. Isotopes When an element has different number of neutrons
Example: Carbon normally has 6; a carbon isotope would have 8 neutrons
Isotopes have similar chemical properties because they have the same # of electrons

9. Radioactive Isotopes
Some isotopes are unstable – their nuclei break down over a period of time
Radioactive dating
Can be used to determine ages of rocks and fossils
Radiation from certain isotopes have help treat cancer

10. Compounds and Molecules
Chemical combination of two or more elements
Example: H2O, NaCl
Elements that make up a compound can be very different from the actual compound (ie: oxygen is a gas at room temperature)
Molecule= smallest unit of compounds

11. Practice using Periodic Table

12. Homework
Pick 5 elements from the Periodic Table and identify the following:
Name
Atomic Number
Atomic Mass
Number of protons, neutrons, electrons

13. Electrons and Bonding
OBJ: Describe the structure of an atom and the role of electrons in bonding

14. Electrons
Bond formation involves the electrons that surround each atomic nucleus
Valence electrons = electrons available to form bonds

15. Chemical Bonds Ionic Bonds Covalent Bonds
When one or more electrons are transferred from one atom to another
When electrons are shared between atoms
Form Molecules

16. Chemical Bonds Ionic Bonds Covalent Bonds
When one or more electrons are transferred from one atom to another
When electrons are shared between atoms
Form Molecules

17. Chemical Bonds Ionic Bonds Covalent Bonds
When one or more electrons are transferred from one atom to another
When electrons are shared between atoms
Form Molecules

18. Chemical Equations

19. Homework: Cayan Biology Flexbook Chemical Bonding Chapter
Practice Questions 1-6

20. Water
OBJ: DESCRIBE THE PROPERTIES OF WATER THAT MAKE IT A UNIQUE SUBSTANCE NECESSARY FOR LIFE.

21. The Water Molecule
Oxygen end of molecule has a slightly negative charge
Hydrogen end of molecule has a slightly positive charge
Polar molecule: uneven distribution of electrons between the oxygen and hydrogen atoms

22. Poles of the Water Molecule

23. Hydrogen Bonds Not very strong Between two water molecules
Water molecules can have multiple hydrogen bonds

24. Cohesion Attraction between molecules of the same substance
Water is cohesive due to hydrogen bonding
Responsible for surface tension

25. Adhesion Attraction between molecules of different substances
Example: water molecules and glass molecules cause water to rise around the graduated cylinders

26. Properties of Water Polarity Cohesion Adhesion Surface tension
Hydrophobic
Hydrophilic

27. OBJ: Define pH and test the pH of various substances
pH, Acids, Bases
OBJ: Define pH and test the pH of various substances

28. The pH Scale Indicates the concentrations of H+ ions in a solution
Ranges from 0-14
7 Neutral
14 very basic
0 very acidic

29. Acids Any compound that forms H+ ions in a solution
Low numbers on the pH scale
Examples: rain, tomato juice, lemon juice, stomach acid

30. Bases Compound that produces hydroxide ions
High numbers on the pH scale
Examples: Milk, Sea water, Soap, Bleach

31. Humans and pH Human fluids must generally be kept at 6.5-7.5
Controlling pH is important for maintaining homeostasis
Medical Example: Heartburn